Commit Graph

240 Commits

Author SHA1 Message Date
Kay Sievers e2ae715d66 kmsg - kmsg_dump() use iterator to receive log buffer content
Provide an iterator to receive the log buffer content, and convert all
kmsg_dump() users to it.

The structured data in the kmsg buffer now contains binary data, which
should no longer be copied verbatim to the kmsg_dump() users.

The iterator should provide reliable access to the buffer data, and also
supports proper log line-aware chunking of data while iterating.

Signed-off-by: Kay Sievers <kay@vrfy.org>
Tested-by: Tony Luck <tony.luck@intel.com>
Reported-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Tested-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-15 14:53:59 -07:00
Andrew Lunn 6ebb017de9 printk: Fix alignment of buf causing crash on ARM EABI
Commit 7ff9554bb5, printk: convert
byte-buffer to variable-length record buffer, causes systems using
EABI to crash very early in the boot cycle. The first entry in struct
log is a u64, which for EABI must be 8 byte aligned.

Make use of __alignof__() so the compiler to decide the alignment, but
allow it to be overridden using CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS,
for systems which can perform unaligned access and want to save
a few bytes of space.

Tested on Orion5x and Kirkwood.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-06-12 16:20:17 -07:00
Kay Sievers c313af145b printk() - isolate KERN_CONT users from ordinary complete lines
Arrange the continuation printk() buffering to be fully separated from the
ordinary full line users.

Limit the exposure to races and wrong printk() line merges to users of
continuation only. Ordinary full line users racing against continuation
users will no longer affect each other.

Multiple continuation users from different threads, racing against each
other will not wrongly be merged into a single line, but printed as
separate lines.

Test output of a kernel module which starts two separate threads which
race against each other, one of them printing a single full terminated
line:
  printk("(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)\n");

The other one printing the line, every character separate in a
continuation loop:
  printk("(C");
  for (i = 0; i < 58; i++)
          printk(KERN_CONT "C");
  printk(KERN_CONT "C)\n");

Behavior of single and non-thread-aware printk() buffer:
  # modprobe printk-race
  printk test init
  (CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  CC(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  C(AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC)
  (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC)

New behavior with separate and thread-aware continuation buffer:
  # modprobe printk-race
  printk test init
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
  (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC)
  (CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC)

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Ingo Molnar  <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-14 12:36:45 -07:00
Kay Sievers 3ce9a7c0ac printk() - restore prefix/timestamp printing for multi-newline strings
Calls like:
  printk("\n *** DEADLOCK ***\n\n");
will print 3 properly indented, separated, syslog + timestamp prefixed lines in
the log output.

Reported-By: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-14 08:42:22 -07:00
Randy Dunlap 1fce677971 printk: add stub for prepend_timestamp()
Add a stub for prepend_timestamp() when CONFIG_PRINTK is not
enabled.  Fixes this build error:

kernel/printk.c:1770:3: error: implicit declaration of function 'prepend_timestamp'

Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-11 16:44:54 -07:00
Stephen Warren f8450fca6e printk: correctly align __log_buf
__log_buf must be aligned, because a 64-bit value is written directly
to it as part of struct log. Alignment of the log entries is typically
handled by log_store(), but this only triggers for subsequent entries,
not the very first (or wrapped) entries.

Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-10 15:36:59 -07:00
Kay Sievers 649e6ee33f printk() - restore timestamp printing at console output
The output of the timestamps got lost with the conversion of the
kmsg buffer to records; restore the old behavior.

Document, that CONFIG_PRINTK_TIME now only controls the output of
the timestamps in the syslog() system call and on the console, and
not the recording of the timestamps.

Cc: Joe Perches <joe@perches.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <levinsasha928@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-09 20:35:06 -07:00
Kay Sievers 5c5d5ca51a printk() - do not merge continuation lines of different threads
This prevents the merging of printk() continuation lines of different
threads, in the case they race against each other.

It should properly isolate "atomic" single-line printk() users from
continuation users, to make sure the single-line users will never be
merged with the racy continuation ones.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-09 20:29:59 -07:00
Kay Sievers 7f3a781d6f printk - fix compilation for CONFIG_PRINTK=n
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-09 15:51:09 -07:00
Kay Sievers 5fc3249068 kmsg: use do_div() to divide 64bit integer
On Tue, May 8, 2012 at 10:02 AM, Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> kernel/built-in.o: In function `devkmsg_read':
> printk.c:(.text+0x27e8): undefined reference to `__udivdi3'
> Most probably the "msg->ts_nsec / 1000" since
> ts_nsec is a u64 and this is a 32 bit build ...

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-08 08:55:26 -07:00
Kay Sievers e11fea92e1 kmsg: export printk records to the /dev/kmsg interface
Support for multiple concurrent readers of /dev/kmsg, with read(),
seek(), poll() support. Output of message sequence numbers, to allow
userspace log consumers to reliably reconnect and reconstruct their
state at any given time. After open("/dev/kmsg"), read() always
returns *all* buffered records. If only future messages should be
read, SEEK_END can be used. In case records get overwritten while
/dev/kmsg is held open, or records get faster overwritten than they
are read, the next read() will return -EPIPE and the current reading
position gets updated to the next available record. The passed
sequence numbers allow the log consumer to calculate the amount of
lost messages.

  [root@mop ~]# cat /dev/kmsg
  5,0,0;Linux version 3.4.0-rc1+ (kay@mop) (gcc version 4.7.0 20120315 ...
  6,159,423091;ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
  7,160,424069;pci_root PNP0A03:00: host bridge window [io  0x0000-0x0cf7] (ignored)
   SUBSYSTEM=acpi
   DEVICE=+acpi:PNP0A03:00
  6,339,5140900;NET: Registered protocol family 10
  30,340,5690716;udevd[80]: starting version 181
  6,341,6081421;FDC 0 is a S82078B
  6,345,6154686;microcode: CPU0 sig=0x623, pf=0x0, revision=0x0
  7,346,6156968;sr 1:0:0:0: Attached scsi CD-ROM sr0
   SUBSYSTEM=scsi
   DEVICE=+scsi:1:0:0:0
  6,347,6289375;microcode: CPU1 sig=0x623, pf=0x0, revision=0x0

Cc: Karel Zak <kzak@redhat.com>
Tested-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-07 17:03:27 -07:00
Kay Sievers 7ff9554bb5 printk: convert byte-buffer to variable-length record buffer
- Record-based stream instead of the traditional byte stream
  buffer. All records carry a 64 bit timestamp, the syslog facility
  and priority in the record header.

- Records consume almost the same amount, sometimes less memory than
  the traditional byte stream buffer (if printk_time is enabled). The record
  header is 16 bytes long, plus some padding bytes at the end if needed.
  The byte-stream buffer needed 3 chars for the syslog prefix, 15 char for
  the timestamp and a newline.

- Buffer management is based on message sequence numbers. When records
  need to be discarded, the reading heads move on to the next full
  record. Unlike the byte-stream buffer, no old logged lines get
  truncated or partly overwritten by new ones. Sequence numbers also
  allow consumers of the log stream to get notified if any message in
  the stream they are about to read gets discarded during the time
  of reading.

- Better buffered IO support for KERN_CONT continuation lines, when printk()
  is called multiple times for a single line. The use of KERN_CONT is now
  mandatory to use continuation; a few places in the kernel need trivial fixes
  here. The buffering could possibly be extended to per-cpu variables to allow
  better thread-safety for multiple printk() invocations for a single line.

- Full-featured syslog facility value support. Different facilities
  can tag their messages. All userspace-injected messages enforce a
  facility value > 0 now, to be able to reliably distinguish them from
  the kernel-generated messages. Independent subsystems like a
  baseband processor running its own firmware, or a kernel-related
  userspace process can use their own unique facility values. Multiple
  independent log streams can co-exist that way in the same
  buffer. All share the same global sequence number counter to ensure
  proper ordering (and interleaving) and to allow the consumers of the
  log to reliably correlate the events from different facilities.

Tested-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Kay Sievers <kay@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-05-07 16:53:02 -07:00
Linus Torvalds 2ba68940c8 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes for v3.4 from Ingo Molnar

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  printk: Make it compile with !CONFIG_PRINTK
  sched/x86: Fix overflow in cyc2ns_offset
  sched: Fix nohz load accounting -- again!
  sched: Update yield() docs
  printk/sched: Introduce special printk_sched() for those awkward moments
  sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer
  sched: Cleanup cpu_active madness
  sched: Fix load-balance wreckage
  sched: Clean up parameter passing of proc_sched_autogroup_set_nice()
  sched: Ditch per cgroup task lists for load-balancing
  sched: Rename load-balancing fields
  sched: Move load-balancing arguments into helper struct
  sched/rt: Do not submit new work when PI-blocked
  sched/rt: Prevent idle task boosting
  sched/wait: Add __wake_up_all_locked() API
  sched/rt: Document scheduler related skip-resched-check sites
  sched/rt: Use schedule_preempt_disabled()
  sched/rt: Add schedule_preempt_disabled()
  sched/rt: Do not throttle when PI boosting
  sched/rt: Keep period timer ticking when rt throttling is active
  ...
2012-03-20 10:31:44 -07:00
Peter Zijlstra 600e145882 printk: Make it compile with !CONFIG_PRINTK
Commit 3ccf3e8306 ("printk/sched: Introduce special
printk_sched() for those awkward moments") overlooked
an #ifdef, so move code around to respect these directives.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Link: http://lkml.kernel.org/r/1331811337.18960.179.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-15 13:38:54 +01:00
Ingo Molnar 47258cf3c4 Linux 3.3-rc7
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Merge tag 'v3.3-rc7' into sched/core

Merge reason: merge back final fixes, prepare for the merge window.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-13 16:26:52 +01:00
Ingo Molnar 35239e23c6 Merge branch 'perf/urgent' into perf/core
Merge reason: We are going to queue up a dependent patch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-12 20:44:11 +01:00
Peter Zijlstra 3ccf3e8306 printk/sched: Introduce special printk_sched() for those awkward moments
There's a few awkward printk()s inside of scheduler guts that people
prefer to keep but really are rather deadlock prone. Fudge around it
by storing the text in a per-cpu buffer and poll it using the existing
printk_tick() handler.

This will drop output when its more frequent than once a tick, however
only the affinity thing could possible go that fast and for that just
one should suffice to notify the admin he's done something silly..

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-wua3lmkt3dg8nfts66o6brne@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2012-03-12 20:43:16 +01:00
Matthew Garrett c22ab33290 kmsg_dump: don't run on non-error paths by default
Since commit 04c6862c05 ("kmsg_dump: add kmsg_dump() calls to the
reboot, halt, poweroff and emergency_restart paths"), kmsg_dump() gets
run on normal paths including poweroff and reboot.

This is less than ideal given pstore implementations that can only
represent single backtraces, since a reboot may overwrite a stored oops
before it's been picked up by userspace.  In addition, some pstore
backends may have low performance and provide a significant delay in
reboot as a result.

This patch adds a printk.always_kmsg_dump kernel parameter (which can also
be changed from userspace).  Without it, the code will only be run on
failure paths rather than on normal paths.  The option can be enabled in
environments where there's a desire to attempt to audit whether or not a
reboot was cleanly requested or not.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Cc: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-05 15:49:42 -08:00
Johannes Berg 9510035849 printk/tracing: Add console output tracing
Add a printk.console trace point to record any printk
messages into the trace, regardless of the current
console loglevel. This can help correlate (existing)
printk debugging with other tracing.

Link: http://lkml.kernel.org/r/1322161388.5366.54.camel@jlt3.sipsolutions.net

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-02-13 13:46:05 -05:00
Rusty Russell 2329abfa34 module_param: make bool parameters really bool (core code)
module_param(bool) used to counter-intuitively take an int.  In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.

It's time to remove the int/unsigned int option.  For this version
it'll simply give a warning, but it'll break next kernel version.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-13 09:32:18 +10:30
Rusty Russell 29d4d6df10 printk: fix unnecessary module_param_name.
You don't need module_param_name if the name is the same!

Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-01-13 09:32:17 +10:30
Linus Torvalds 1483b38235 Merge branch 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
* 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  printk, lockdep: Switch to tracked irq ops
  printk, lockdep: Remove superfluous preempt_disable()
  printk, lockdep: Disable lock debugging on zap_locks()
2012-01-06 08:01:59 -08:00
Ingo Molnar 45aa0663cc Merge branch 'memblock-kill-early_node_map' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into core/memblock 2011-12-20 12:14:26 +01:00
Peter Zijlstra 09dc3cf93f printk: avoid double lock acquire
Commit 4f2a8d3cf5 ("printk: Fix console_sem vs logbuf_lock unlock race")
introduced another silly bug where we would want to acquire an already
held lock.  Avoid this.

Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-09 07:50:28 -08:00
Tejun Heo d4bbf7e775 Merge branch 'master' into x86/memblock
Conflicts & resolutions:

* arch/x86/xen/setup.c

	dc91c728fd "xen: allow extra memory to be in multiple regions"
	24aa07882b "memblock, x86: Replace memblock_x86_reserve/free..."

	conflicted on xen_add_extra_mem() updates.  The resolution is
	trivial as the latter just want to replace
	memblock_x86_reserve_range() with memblock_reserve().

* drivers/pci/intel-iommu.c

	166e9278a3 "x86/ia64: intel-iommu: move to drivers/iommu/"
	5dfe8660a3 "bootmem: Replace work_with_active_regions() with..."

	conflicted as the former moved the file under drivers/iommu/.
	Resolved by applying the chnages from the latter on the moved
	file.

* mm/Kconfig

	6661672053 "memblock: add NO_BOOTMEM config symbol"
	c378ddd53f "memblock, x86: Make ARCH_DISCARD_MEMBLOCK a config option"

	conflicted trivially.  Both added config options.  Just
	letting both add their own options resolves the conflict.

* mm/memblock.c

	d1f0ece6cd "mm/memblock.c: small function definition fixes"
	ed7b56a799 "memblock: Remove memblock_memory_can_coalesce()"

	confliected.  The former updates function removed by the
	latter.  Resolution is trivial.

Signed-off-by: Tejun Heo <tj@kernel.org>
2011-11-28 09:46:22 -08:00
Peter Zijlstra 1a9a8aefa8 printk, lockdep: Switch to tracked irq ops
Switch to local_irq_ ops so that the irq state is properly tracked
(raw_local_irq_* isn't tracked by lockdep, causing confusion).

Possible now that commit dd4e5d3ac4 ("lockdep: Fix
trace_[soft,hard]irqs_[on,off]() recursion") cured the reason we
needed the raw_ ops.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-14 13:35:20 +01:00
Peter Zijlstra 47ff5c95db printk, lockdep: Remove superfluous preempt_disable()
The raw_lock_irq_{save,restore}() already implies a
non-preemptibility.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-14 13:35:18 +01:00
Peter Zijlstra 94d24fc472 printk, lockdep: Disable lock debugging on zap_locks()
zap_locks() is used by printk() in a last ditch effort to get data
out, clearly we cannot trust lock state after this so make it disable
lock debugging.

Also don't treat printk recursion through lockdep as a normal
recursion bug but try hard to get the lockdep splat out.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-kqxwmo4xz37e1s8w0xopvr0q@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-11-14 13:35:16 +01:00
William Douglas ae29bc92da printk: remove bounds checking for log_prefix
Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).

Since the code being updated works because strtoul bombs out (endp isn't
updated) and 0 is returned anyway just remove the check and don't change
the behavior of the function.

Signed-off-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:53 -07:00
William Douglas 48e41899e4 printk: fix bounds checking for log_prefix
Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).  It should be testing to see if the character less than '0' or
greater than '9' instead.  This patch makes that change.

The code being changed worked because strtoul bombs out (endp isn't
updated) and 0 is returned anyway.

Signed-off-by: William Douglas <william.douglas@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:53 -07:00
Yanmin Zhang 134620f7a8 printk: add console_suspend module parameter
We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off console_suspend_enabled frequently.

Add a module parameter, so users could change it by:
/sys/module/printk/parameters/console_suspend

Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:53 -07:00
Yanmin Zhang 0eca6b7c78 printk: add module parameter ignore_loglevel to control ignore_loglevel
We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off ignore_loglevel frequently without
rebooting.

Add a module parameter, so users can change it by:
/sys/module/printk/parameters/ignore_loglevel

Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-31 17:30:53 -07:00
Thomas Gleixner 07354eb1a7 locking, printk: Annotate logbuf_lock as raw
The logbuf_lock lock can be taken in atomic context and therefore
cannot be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[ merged and fixed it ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-09-13 11:11:54 +02:00
Nishanth Aravamudan 4c30c6f566 kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon
It seems that 7bf693951a ("console: allow to retain boot console via
boot option keep_bootcon") doesn't always achieve what it aims, as when
printk_late_init() runs it unconditionally turns off all boot consoles.
With this patch, I am able to see more messages on the boot console in
KVM guests than I can without, when keep_bootcon is specified.

I think it is appropriate for the relevant -stable trees.  However, it's
more of an annoyance than a serious bug (ideally you don't need to keep
the boot console around as console handover should be working -- I was
encountering a situation where the console handover wasn't working and
not having the boot console available meant I couldn't see why).

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <gregkh@suse.de>
Acked-by: Fabio M. Di Nitto <fdinitto@redhat.com>
Cc: <stable@kernel.org>		[2.6.39.x, 3.0.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25 16:25:34 -07:00
Jonathan Nieder f2c0d0266c cap_syslog: don't use WARN_ONCE for CAP_SYS_ADMIN deprecation warning
syslog-ng versions before 3.3.0beta1 (2011-05-12) assume that
CAP_SYS_ADMIN is sufficient to access syslog, so ever since CAP_SYSLOG
was introduced (2010-11-25) they have triggered a warning.

Commit ee24aebffb ("cap_syslog: accept CAP_SYS_ADMIN for now")
improved matters a little by making syslog-ng work again, just keeping
the WARN_ONCE().  But still, this is a warning that writes a stack trace
we don't care about to syslog, sets a taint flag, and alarms sysadmins
when nothing worse has happened than use of an old userspace with a
recent kernel.

Convert the WARN_ONCE to a printk_once to avoid that while continuing to
give userspace developers a hint that this is an unwanted
backward-compatibility feature and won't be around forever.

Reported-by: Ralf Hildebrandt <ralf.hildebrandt@charite.de>
Reported-by: Niels <zorglub_olsen@hotmail.com>
Reported-by: Paweł Sikora <pluto@agmk.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Liked-by: Gergely Nagy <algernon@madhouse-project.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-09 18:22:22 -07:00
Tejun Heo 1f5026a7e2 memblock: Kill MEMBLOCK_ERROR
25818f0f28 (memblock: Make MEMBLOCK_ERROR be 0) thankfully made
MEMBLOCK_ERROR 0 and there already are codes which expect error return
to be 0.  There's no point in keeping MEMBLOCK_ERROR around.  End its
misery.

Signed-off-by: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/1310457490-3356-6-git-send-email-tj@kernel.org
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-07-13 16:36:01 -07:00
Peter Zijlstra 4f2a8d3cf5 printk: Fix console_sem vs logbuf_lock unlock race
Fix up the fallout from commit 0b5e1c5255 ("printk: Release
console_sem after logbuf_lock").

The reason for unlocking the console_sem under the logbuf_lock
is that a concurrent printk() might fill up the buffer but fail
to acquire the console sem, resulting in a missed write to the
console until a subsequent console_sem acquire/release cycle.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: efault@gmx.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1308734409.1022.14.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-22 11:39:34 +02:00
Peter Zijlstra 0b5e1c5255 printk: Release console_sem after logbuf_lock
Release console_sem after unlocking the logbuf_lock so that we don't
generate wakeups while holding logbuf_lock. This avoids some lock
inversion troubles once we remove the lockdep_off bits between
logbuf_lock and rq->lock (prints while holding rq->lock vs doing
wakeups while holding logbuf_lock).

There's of course still an actual deadlock where the printk()s under
rq->lock will issue a wakeup from the up() call, but lockdep won't
warn about that since semaphores are not tracked.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-j8swthl12u73h4znbvitljzd@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-07 12:50:02 +02:00
Mike Travis 162a7e7500 printk: allocate kernel log buffer earlier
On larger systems, because of the numerous ACPI, Bootmem and EFI messages,
the static log buffer overflows before the larger one specified by the
log_buf_len param is allocated.  Minimize the overflow by allocating the
new log buffer as soon as possible.

On kernels without memblock, a later call to setup_log_buf from
kernel/init.c is the fallback.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_PRINTK=n build]
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-25 08:39:48 -07:00
Mandeep Singh Baines 5af5bcb8d3 printk: allow setting DEFAULT_MESSAGE_LEVEL via Kconfig
We've been burned by regressions/bugs which we later realized could have
been triaged quicker if only we'd paid closer attention to dmesg.  To make
it easier to audit dmesg, we'd like to make DEFAULT_MESSAGE_LEVEL
Kconfig-settable.  That way we can set it to KERN_NOTICE and audit any
messages <= KERN_WARNING.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joe Perches <joe@perches.com>
Cc: Olof Johansson <olofj@chromium.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-22 17:44:13 -07:00
Feng Tang fe3d8ad31c console: prevent registered consoles from dumping old kernel message over again
For a platform with many consoles like:
 "console=tty1 console=ttyMFD2 console=ttyS0 earlyprintk=mrst"

Each time when the non "selected_console" (tty1 and ttyMFD2 here) get
registered, the existing kernel message will be printed out on registered
consoles again, the "mrst" early console will get some same message for 3
times, and "tty1" will get some for twice.

As suggested by Andrew Morton, every time a new console is registered, it
will be set as the "exclusive" console which will dump the already
existing kernel messages.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: Greg KH <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-22 17:44:12 -07:00
Fabio M. Di Nitto 7bf693951a console: allow to retain boot console via boot option keep_bootcon
On some architectures, the boot process involves de-registering the boot
console (early boot), initialize drivers and then re-register the console.

This mechanism introduces a window in which no printk can happen on the
console and messages are buffered and then printed once the new console is
available.

If a kernel crashes during this window, all it's left on the boot console
is "console [foo] enabled, bootconsole disabled" making debug of the crash
rather 'interesting'.

By adding "keep_bootcon" option, do not unregister the boot console, that
will allow to printk everything that is happening up to the crash.

The option is clearly meant only for debugging purposes as it introduces
lots of duplicated info printed on console, but will make bug report from
users easier as it doesn't require a kernel build just to figure out where
we crash.

Signed-off-by: Fabio M. Di Nitto <fabbione@fabbione.net>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-22 17:44:12 -07:00
Linus Torvalds a5e6b135bd Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6
* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6: (50 commits)
  printk: do not mangle valid userspace syslog prefixes
  efivars: Add Documentation
  efivars: Expose efivars functionality to external drivers.
  efivars: Parameterize operations.
  efivars: Split out variable registration
  efivars: parameterize efivars
  efivars: Make efivars bin_attributes dynamic
  efivars: move efivars globals into struct efivars
  drivers:misc: ti-st: fix debugging code
  kref: Fix typo in kref documentation
  UIO: add PRUSS UIO driver support
  Fix spelling mistakes in Documentation/zh_CN/SubmittingPatches
  firmware: Fix unaligned memory accesses in dmi-sysfs
  firmware: Add documentation for /sys/firmware/dmi
  firmware: Expose DMI type 15 System Event Log
  firmware: Break out system_event_log in dmi-sysfs
  firmware: Basic dmi-sysfs support
  firmware: Add DMI entry types to the headers
  Driver core: convert platform_{get,set}_drvdata to static inline functions
  Translate linux-2.6/Documentation/magic-number.txt into Chinese
  ...
2011-03-16 15:05:40 -07:00
Kay Sievers 9d90c8d9cd printk: do not mangle valid userspace syslog prefixes
printk: do not mangle valid userspace syslog prefixes with /dev/kmsg

Log messages passed to the kernel log by using /dev/kmsg or /dev/ttyprintk
might contain a syslog prefix including the syslog facility value.

This makes printk to recognize these headers properly, extract the real log
level from it to use, and add the prefix as a proper prefix to the
log buffer, instead of wrongly printing it as the log message text.

Before:
  $ echo '<14>text' > /dev/kmsg
  $ dmesg -r
  <4>[135159.594810] <14>text

After:
  $ echo '<14>text' > /dev/kmsg
  $ dmesg -r
  <14>[   50.750654] text

Cc: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-03-14 08:49:16 -07:00
Linus Torvalds ee24aebffb cap_syslog: accept CAP_SYS_ADMIN for now
In commit ce6ada35bd ("security: Define CAP_SYSLOG") Serge Hallyn
introduced CAP_SYSLOG, but broke backwards compatibility by no longer
accepting CAP_SYS_ADMIN as an override (it would cause a warning and
then reject the operation).

Re-instate CAP_SYS_ADMIN - but keeping the warning - as an acceptable
capability until any legacy applications have been updated.  There are
apparently applications out there that drop all capabilities except for
CAP_SYS_ADMIN in order to access the syslog.

(This is a re-implementation of a patch by Serge, cleaning the logic up
and making the code more readable)

Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-10 17:53:55 -08:00
Torben Hohn ac751efa6a console: rename acquire/release_console_sem() to console_lock/unlock()
The -rt patches change the console_semaphore to console_mutex.  As a
result, a quite large chunk of the patches changes all
acquire/release_console_sem() to acquire/release_console_mutex()

This commit makes things use more neutral function names which dont make
implications about the underlying lock.

The only real change is the return value of console_trylock which is
inverted from try_acquire_console_sem()

This patch also paves the way to switching console_sem from a semaphore to
a mutex.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: make console_trylock return 1 on success, per Geert]
Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: Thomas Gleixner <tglx@tglx.de>
Cc: Greg KH <gregkh@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-26 10:50:06 +10:00
Huang Ying fb842b00c5 printk: use RCU to prevent potential lock contention in kmsg_dump
dump_list_lock is used to protect dump_list in kmsg_dumper implementation,
kmsg_dump() uses it to traverse dump_list too.  But if there is contention
on the lock, kmsg_dump() will fail, and the valuable kernel message may be
lost.

This patch solves this issue with RCU.  Because kmsg_dump() only read the
list, no lock is needed in kmsg_dump().  So that kmsg_dump() will never
fail because of lock contention.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13 08:03:09 -08:00
Seiji Aguchi 04c6862c05 kmsg_dump: add kmsg_dump() calls to the reboot, halt, poweroff and emergency_restart paths
We need to know the reason why system rebooted in support service.
However, we can't inform our customers of the reason because final
messages are lost on current Linux kernel.

This patch improves the situation above because the final messages are
saved by adding kmsg_dump() to reboot, halt, poweroff and
emergency_restart path.

Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Reviewed-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-13 08:03:07 -08:00
James Morris d2e7ad1922 Merge branch 'master' into next
Conflicts:
	security/smack/smack_lsm.c

Verified and added fix by Stephen Rothwell <sfr@canb.auug.org.au>
Ok'd by Casey Schaufler <casey@schaufler-ca.com>

Signed-off-by: James Morris <jmorris@namei.org>
2011-01-10 09:46:24 +11:00
Linus Torvalds 56b85f32d5 Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (36 commits)
  serial: apbuart: Fixup apbuart_console_init()
  TTY: Add tty ioctl to figure device node of the system console.
  tty: add 'active' sysfs attribute to tty0 and console device
  drivers: serial: apbuart: Handle OF failures gracefully
  Serial: Avoid unbalanced IRQ wake disable during resume
  tty: fix typos/errors in tty_driver.h comments
  pch_uart : fix warnings for 64bit compile
  8250: fix uninitialized FIFOs
  ip2: fix compiler warning on ip2main_pci_tbl
  specialix: fix compiler warning on specialix_pci_tbl
  rocket: fix compiler warning on rocket_pci_ids
  8250: add a UPIO_DWAPB32 for 32 bit accesses
  8250: use container_of() instead of casting
  serial: omap-serial: Add support for kernel debugger
  serial: fix pch_uart kconfig & build
  drivers: char: hvc: add arm JTAG DCC console support
  RS485 documentation: add 16C950 UART description
  serial: ifx6x60: fix memory leak
  serial: ifx6x60: free IRQ on error
  Serial: EG20T: add PCH_UART driver
  ...

Fixed up conflicts in drivers/serial/apbuart.c with evil merge that
makes the code look fairly sane (unlike either side).
2011-01-07 14:39:20 -08:00
Kay Sievers fbc92a3455 tty: add 'active' sysfs attribute to tty0 and console device
tty: add 'active' sysfs attribute to tty0 and console device

Userspace can query the actual virtual console, and the configured
console devices behind /dev/tt0 and /dev/console.

The last entry in the list of devices is the active device, analog
to the console= kernel command line option.

The attribute supports poll(), which is raised when the virtual
console is changed or /dev/console is reconfigured.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

index 0000000..b138b66
2010-12-16 16:15:34 -08:00
Serge E. Hallyn 38ef4c2e43 syslog: check cap_syslog when dmesg_restrict
Eric Paris pointed out that it doesn't make sense to require
both CAP_SYS_ADMIN and CAP_SYSLOG for certain syslog actions.
So require CAP_SYSLOG, not CAP_SYS_ADMIN, when dmesg_restrict
is set.

(I'm also consolidating the now common error path)

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-12-09 09:48:48 +11:00
Eric Dumazet 40dc11ffb3 printk: Use this_cpu_{read|write} api on printk_pending
__get_cpu_var() is a bit inefficient, lets use __this_cpu_read() and
__this_cpu_write() to manipulate printk_pending.

printk_needs_cpu(cpu) is called only for the current cpu :
Use faster __this_cpu_read().

Remove the redundant unlikely on (cpu_is_offline(cpu)) test:

 # size kernel/printk.o*
   text	   data	    bss	    dec	    hex	filename
   9942	    756	 263488	 274186	  42f0a	kernel/printk.o.new
   9990	    756	 263488	 274234	  42f3a	kernel/printk.o.old

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1290788536.2855.237.camel@edumazet-laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-12-08 20:16:01 +01:00
Serge E. Hallyn ce6ada35bd security: Define CAP_SYSLOG
Privileged syslog operations currently require CAP_SYS_ADMIN.  Split
this off into a new CAP_SYSLOG privilege which we can sanely take away
from a container through the capability bounding set.

With this patch, an lxc container can be prevented from messing with
the host's syslog (i.e. dmesg -c).

Changelog: mar 12 2010: add selinux capability2:cap_syslog perm
Changelog: nov 22 2010:
	. port to new kernel
	. add a WARN_ONCE if userspace isn't using CAP_SYSLOG

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Andrew G. Morgan <morgan@kernel.org>
Acked-By: Kees Cook <kees.cook@canonical.com>
Cc: James Morris <jmorris@namei.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: "Christopher J. PeBenito" <cpebenito@tresys.com>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: James Morris <jmorris@namei.org>
2010-11-29 08:35:12 +11:00
Heiko Carstens 61ab25447a nohz: Fix printk_needs_cpu() return value on offline cpus
This patch fixes a hang observed with 2.6.32 kernels where timers got enqueued
on offline cpus.

printk_needs_cpu() may return 1 if called on offline cpus. When a cpu gets
offlined it schedules the idle process which, before killing its own cpu, will
call tick_nohz_stop_sched_tick(). That function in turn will call
printk_needs_cpu() in order to check if the local tick can be disabled. On
offline cpus this function should naturally return 0 since regardless if the
tick gets disabled or not the cpu will be dead short after. That is besides the
fact that __cpu_disable() should already have made sure that no interrupts on
the offlined cpu will be delivered anyway.

In this case it prevents tick_nohz_stop_sched_tick() to call
select_nohz_load_balancer(). No idea if that really is a problem. However what
made me debug this is that on 2.6.32 the function get_nohz_load_balancer() is
used within __mod_timer() to select a cpu on which a timer gets enqueued. If
printk_needs_cpu() returns 1 then the nohz_load_balancer cpu doesn't get
updated when a cpu gets offlined. It may contain the cpu number of an offline
cpu. In turn timers get enqueued on an offline cpu and not very surprisingly
they never expire and cause system hangs.

This has been observed 2.6.32 kernels. On current kernels __mod_timer() uses
get_nohz_timer_target() which doesn't have that problem. However there might be
other problems because of the too early exit tick_nohz_stop_sched_tick() in
case a cpu goes offline.

Easiest way to fix this is just to test if the current cpu is offline and call
printk_tick() directly which clears the condition.

Alternatively I tried a cpu hotplug notifier which would clear the condition,
however between calling the notifier function and printk_needs_cpu() something
could have called printk() again and the problem is back again. This seems to
be the safest fix.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
LKML-Reference: <20101126120235.406766476@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-11-26 15:03:12 +01:00
Heiko Carstens 49f4138346 printk: Fix wake_up_klogd() vs cpu hotplug
wake_up_klogd() may get called from preemptible context but uses
__raw_get_cpu_var() to write to a per cpu variable. If it gets preempted
between getting the address and writing to it, the cpu in question could be
offline if the process gets scheduled back and hence writes to the per cpu data
of an offline cpu.

This buggy behaviour was introduced with fa33507a "printk: robustify
printk, fix #2" which was supposed to fix a "using smp_processor_id() in
preemptible" warning.

Let's use this_cpu_write() instead which disables preemption and makes sure
that the outlined scenario cannot happen.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101126124247.GC7023@osiris.boeblingen.de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-11-26 15:03:11 +01:00
Jiri Slaby a75d946f42 console: move for_each_console to linux/console.h
Move it out of printk.c so that we can use it all over the code. There
are some potential users which will be converted to that macro in next
patches.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-11-16 12:50:17 -08:00
Eric Paris 12b3052c3e capabilities/syslog: open code cap_syslog logic to fix build failure
The addition of CONFIG_SECURITY_DMESG_RESTRICT resulted in a build
failure when CONFIG_PRINTK=n.  This is because the capabilities code
which used the new option was built even though the variable in question
didn't exist.

The patch here fixes this by moving the capabilities checks out of the
LSM and into the caller.  All (known) LSMs should have been calling the
capabilities hook already so it actually makes the code organization
better to eliminate the hook altogether.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-15 15:40:01 -08:00
Dan Rosenberg eaf06b241b Restrict unprivileged access to kernel syslog
The kernel syslog contains debugging information that is often useful
during exploitation of other vulnerabilities, such as kernel heap
addresses.  Rather than futilely attempt to sanitize hundreds (or
thousands) of printk statements and simultaneously cripple useful
debugging functionality, it is far simpler to create an option that
prevents unprivileged users from reading the syslog.

This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the
dmesg_restrict sysctl.  When set to "0", the default, no restrictions are
enforced.  When set to "1", only users with CAP_SYS_ADMIN can read the
kernel syslog via dmesg(8) or other mechanisms.

[akpm@linux-foundation.org: explain the config option in kernel.txt]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Eugene Teo <eugeneteo@kernel.org>
Acked-by: Kees Cook <kees.cook@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-12 07:55:32 -08:00
Namhyung Kim 674dff6507 printk: change type of 'boot_delay' to int *
get_option() takes its 2nd arg as int * so passing boot_delay to it
caused following warnings from sparse:

 kernel/printk.c:223:27: warning: incorrect type in argument 2 (different signedness)
 kernel/printk.c:223:27:    expected int *pint
 kernel/printk.c:223:27:    got unsigned int static [toplevel] *<noident>

Since boot_delay can't grow more than 10,000 changing it to 'int *'
will not produce any problem.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 16:52:16 -07:00
Namhyung Kim 8155c02a44 printk: add lock context annotation
acquire_console_semaphore_for_printk() releases logbuf_lock but
was missing proper annotation. Add it.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 16:52:16 -07:00
Namhyung Kim 6c095efd82 printk: fixup declaration of kmsg_reasons
Move redundant 'const' after '*' to make pointer itself const

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 16:52:16 -07:00
Thomas Gleixner 5b8c4f23c5 printk: Make console_sem a semaphore not a pseudo mutex
It needs to be investigated whether it can be replaced by a real
mutex, but that needs more thought.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
LKML-Reference: <20100907125057.179587334@linutronix.de>
2010-10-12 17:36:10 +02:00
Andi Kleen 8c4af38e9b gcc-4.6: printk: use stable variable to dump kmsg buffer
kmsg_dump takes care to sample the global variables
inside a spinlock, but then goes on to use the same
variables outside the spinlock region too.

Use the correct variable. This will make the race
window smaller.

Found by gcc 4.6's new warnings.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09 20:45:06 -07:00
Kevin Cernekee 034260d677 printk: fix delayed messages from CPU hotplug events
When a secondary CPU is being brought up, it is not uncommon for
printk() to be invoked when cpu_online(smp_processor_id()) == 0.  The
case that I witnessed personally was on MIPS:

http://lkml.org/lkml/2010/5/30/4

If (can_use_console() == 0), printk() will spool its output to log_buf
and it will be visible in "dmesg", but that output will NOT be echoed to
the console until somebody calls release_console_sem() from a CPU that
is online.  Therefore, the boot time messages from the new CPU can get
stuck in "limbo" for a long time, and might suddenly appear on the
screen when a completely unrelated event (e.g. "eth0: link is down")
occurs.

This patch modifies the console code so that any pending messages are
automatically flushed out to the console whenever a CPU hotplug
operation completes successfully or aborts.

The issue was seen on 2.6.34.

Original patch by Kevin Cernekee with cleanups by akpm and additional fixes
by Santosh Shilimkar.  This patch superseeds
https://patchwork.linux-mips.org/patch/1357/.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
To: <mingo@elte.hu>
To: <akpm@linux-foundation.org>
To: <simon.kagstrom@netinsight.net>
To: <David.Woodhouse@intel.com>
To: <lethal@linux-sh.org>
Cc: <linux-kernel@vger.kernel.org>
Cc: <linux-mips@linux-mips.org>
Reviewed-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1534/
LKML-Reference: <ede63b5a20af951c755736f035d1e787772d7c28@localhost>
LKML-Reference: <EAF47CD23C76F840A9E7FCE10091EFAB02C5DB6D1F@dbde02.ent.ti.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2010-08-05 13:25:59 +01:00
Jason Wessel d37d39ae3b printk,kdb: capture printk() when in kdb shell
Certain calls from the kdb shell will call out to printk(), and any of
these calls should get vectored back to the kdb_printf() so that the
kdb pager and processing can be used, as well as to properly channel
I/O to the polled I/O devices.

CC: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
2010-05-20 21:04:27 -05:00
Jason Wessel 67fc4e0cb9 kdb: core for kgdb back end (2 of 2)
This patch contains the hooks and instrumentation into kernel which
live outside the kernel/debug directory, which the kdb core
will call to run commands like lsmod, dmesg, bt etc...

CC: linux-arch@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Martin Hicks <mort@sgi.com>
2010-05-20 21:04:21 -05:00
Gustavo F. Padovan cea83886dd printk: avoid warning when CONFIG_PRINTK is disabled
kernel/printk.c:72: warning: `saved_console_loglevel' defined but not used

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-06 11:26:33 -08:00
James Morris b4ccebdd37 Merge branch 'next' into for-linus 2010-03-01 09:36:31 +11:00
Kees Cook d78ca3cd73 syslog: use defined constants instead of raw numbers
Right now the syslog "type" action are just raw numbers which makes
the source difficult to follow.  This patch replaces the raw numbers
with defined constants for some level of sanity.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-02-04 14:20:41 +11:00
Kees Cook 002345925e syslog: distinguish between /proc/kmsg and syscalls
This allows the LSM to distinguish between syslog functions originating
from /proc/kmsg access and direct syscalls.  By default, the commoncaps
will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg
file descriptor.  For example the kernel syslog reader can now drop
privileges after opening /proc/kmsg, instead of staying privileged with
CAP_SYS_ADMIN.  MAC systems that implement security_syslog have unchanged
behavior.

Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-02-04 14:20:12 +11:00
Linus Torvalds b8be634e01 Merge git://git.infradead.org/~dwmw2/mtd-2.6.33
* git://git.infradead.org/~dwmw2/mtd-2.6.33:
  mtd: tests: fix read, speed and stress tests on NOR flash
  mtd: Really add ARM pismo support
  kmsg_dump: Dump on crash_kexec as well
2010-01-24 10:31:34 -08:00
KOSAKI Motohiro 0f4bd46ec2 kmsg_dump: Dump on crash_kexec as well
crash_kexec gets called before kmsg_dump(KMSG_DUMP_OOPS) if
panic_on_oops is set, so the kernel log buffer is not stored
for this case.

This patch adds a KMSG_DUMP_KEXEC dump type which gets called
when crash_kexec() is invoked. To avoid getting double dumps,
the old KMSG_DUMP_PANIC is moved below crash_kexec(). The
mtdoops driver is modified to handle KMSG_DUMP_KEXEC in the
same way as a panic.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2009-12-31 19:45:04 +00:00
Randy Dunlap 6485536bcf printk: fix new kernel-doc warnings
Fix kernel-doc warnings in printk.c:

Warning(kernel/printk.c:1422): No description found for parameter 'dumper'
Warning(kernel/printk.c:1422): Excess function parameter 'dump' description in 'kmsg_dump_register'
Warning(kernel/printk.c:1451): No description found for parameter 'dumper'
Warning(kernel/printk.c:1451): Excess function parameter 'dump' description in 'kmsg_dump_unregister'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-17 15:45:32 -08:00
Linus Torvalds 60d9aa758c Merge git://git.infradead.org/mtd-2.6
* git://git.infradead.org/mtd-2.6: (90 commits)
  jffs2: Fix long-standing bug with symlink garbage collection.
  mtd: OneNAND: Fix test of unsigned in onenand_otp_walk()
  mtd: cfi_cmdset_0002, fix lock imbalance
  Revert "mtd: move mxcnd_remove to .exit.text"
  mtd: m25p80: add support for Macronix MX25L4005A
  kmsg_dump: fix build for CONFIG_PRINTK=n
  mtd: nandsim: add support for 4KiB pages
  mtd: mtdoops: refactor as a kmsg_dumper
  mtd: mtdoops: make record size configurable
  mtd: mtdoops: limit the maximum mtd partition size
  mtd: mtdoops: keep track of used/unused pages in an array
  mtd: mtdoops: several minor cleanups
  core: Add kernel message dumper to call on oopses and panics
  mtd: add ARM pismo support
  mtd: pxa3xx_nand: Fix PIO data transfer
  mtd: nand: fix multi-chip suspend problem
  mtd: add support for switching old SST chips into QRY mode
  mtd: fix M29W800D dev_id and uaddr
  mtd: don't use PF_MEMALLOC
  mtd: Add bad block table overrides to Davinci NAND driver
  ...

Fixed up conflicts (mostly trivial) in
	drivers/mtd/devices/m25p80.c
	drivers/mtd/maps/pcmciamtd.c
	drivers/mtd/nand/pxa3xx_nand.c
	kernel/printk.c
2009-12-16 10:23:43 -08:00
Linus Torvalds d0b093a8b5 Merge branch 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  ratelimit: Make suppressed output messages more useful
  printk: Remove ratelimit.h from kernel.h
  ratelimit: Fix/allow use in atomic contexts
  ratelimit: Use per ratelimit context locking
2009-12-05 09:50:22 -08:00
Randy Dunlap 595dd3d8bf kmsg_dump: fix build for CONFIG_PRINTK=n
kmsg_dump() fails to build when CONFIG_PRINTK=n; provide stubs
for the kmsg_dump*() functions when CONFIG_PRINTK=n.

kernel/printk.c: In function 'kmsg_dump':
kernel/printk.c:1501: error: 'log_buf_len' undeclared (first use in this function)
kernel/printk.c:1502: error: 'logged_chars' undeclared (first use in this function)
kernel/printk.c:1506: error: 'log_buf' undeclared (first use in this function)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2009-12-02 08:44:33 +00:00
Simon Kagstrom 456b565cc5 core: Add kernel message dumper to call on oopses and panics
The core functionality is implemented as per Linus suggestion from

  http://lists.infradead.org/pipermail/linux-mtd/2009-October/027620.html

(with the kmsg_dump implementation by Linus). A struct kmsg_dumper has
been added which contains a callback to dump the kernel log buffers on
crashes. The kmsg_dump function gets called from oops_exit() and panic()
and invokes this callbacks with the crash reason.

[dwmw2: Fix log_end handling]
Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Reviewed-by: Anders Grafstrom <anders.grafstrom@netinsight.net>
Reviewed-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
2009-11-30 12:01:49 +00:00
Christian Borntraeger 5c82871335 ratelimit: Make suppressed output messages more useful
Today I got:

  [39648.224782] Registered led device: iwl-phy0::TX
  [40676.545099] __ratelimit: 246 callbacks suppressed
  [40676.545103] abcdef[23675]: segfault at 0 ...

as you can see the ratelimit message contains a function prefix.
Since this is always __ratelimit, this wont help much.

This patch changes __ratelimit and printk_ratelimit to print the
function name that calls ratelimit.

This will pinpoint the responsible function, as long as not several
different places call ratelimit with the same ratelimit state at
the same time. In that case we catch only one random function that
calls ratelimit after the wait period.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Young <hidave.darkstar@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <200910231458.11832.borntraeger@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-23 17:26:37 +02:00
Dave Young af91322ef3 printk: add printk_delay to make messages readable for some scenarios
When syslog is not possible, at the same time there's no serial/net
console available, it will be hard to read the printk messages.  For
example oops/panic/warning messages in shutdown phase.

Add a printk delay feature, we can make each printk message delay some
milliseconds.

Setting the delay by proc/sysctl interface: /proc/sys/kernel/printk_delay

The value range from 0 - 10000, default value is 0

[akpm@linux-foundation.org: fix a few things]
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23 07:39:28 -07:00
Dave Young 3a3b6ed223 printk boot_delay: rename printk_delay_msec to loops_per_msec
Rename `printk_delay_msec' to `loops_per_msec', because the patch "printk:
add printk_delay to make messages readable for some scenarios" wishes to
more appropriately use the `printk_delay_msec' identifier.

[akpm@linux-foundation.org: add a comment]
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23 07:39:28 -07:00
Ingo Molnar 3fff4c42bd printk: Remove ratelimit.h from kernel.h
Decouple kernel.h from ratelimit.h: the global declaration of
printk's ratelimit_state is not needed, and it leads to messy
circular dependencies due to ratelimit.h's (new) adding of a
spinlock_types.h include.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David S. Miller <davem@davemloft.net>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-22 16:18:09 +02:00
Anirban Sinha 353f6dd2de cleanup console_print()
console_print() is an old legacy interface mostly unused in the entire
kernel tree. It's best to clean up its existing use and let developers
use their own implementation of it as they feel fit.

Signed-off-by: Anirban Sinha <asinha@zeugmasystems.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-14 17:41:42 -07:00
Sonic Zhang 42c2c8c854 printk: Fix "printk: Enable the use of more than one CON_BOOT (early console)"
Don't return when we find the first bootconsole - it can leave
other bootconsoles still installed, and they can be used and
cause problems later (if they are in the init section, and
eventually released), and cause problems.  Make sure we remove
all of them.

Signed-off-by: Sonic Zhang <Sonic.Zhang@analog.com>
Signed-off-by: Robin Getz <rgetz@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-08-08 18:27:37 +02:00
Frans Pop 1aaad49e85 printk: Restore previous console_loglevel when re-enabling logging
When logging to console is disabled from userspace using klogctl()
and later re-enabled, console_loglevel gets set to the default
log level instead to the previous value.

This means that if the kernel was booted with 'quiet', the boot is
suddenly no longer quiet after logging to console gets re-enabled.

Save the current console_loglevel when logging is disabled and
restore to that value. If the log level is set to a specific value
while disabled, this is interpreted as an implicit re-enabling of
the logging.

The problem that prompted this patch is described in:

    http://lkml.org/lkml/2009/6/28/234

There are two variations possible on the patch below:

 1) If klogctl(7) is called while logging is not disabled, then set level
    to default (partially preserving current functionality):
  	case 7:		/* Enable logging to console */
 -		console_loglevel = default_console_loglevel;
 +		if (saved_console_loglevel == -1)
 +			console_loglevel = default_console_loglevel;
 +		else {
 +			console_loglevel = saved_console_loglevel;
 +			saved_console_loglevel = -1;
 +		}

 2) If klogctl(8) is called while logging is disabled, then don't enable
    logging, but remember the requested value for when logging does get
    enabled again:
  	case 8:		/* Set level of messages printed to console */
 [...]
 - 		console_loglevel = len;
 +		if (saved_console_loglevel == -1)
 +			console_loglevel = len;
 +		else
 +			saved_console_loglevel = len;

Yet another option would be to ignore the request.

Signed-off-by: Frans Pop <elendil@planet.nl>
Cc: cryptsetup@packages.debian.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <200907061331.49930.elendil@planet.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-10 16:02:23 +02:00
Robin Getz 8259cf4342 printk: Ensure that "console enabled" messages are printed on the console
Today, when a console is registered without CON_PRINTBUFFER,
end users never see the announcement of it being added, and
never know if they missed something, if the console is really
at the start or not, and just leads to general confusion.

This re-orders existing code, to make sure the console is
added, before the "console [%s%d] enabled" is printed out -
ensuring that this message is _always_ seen.

This has the desired/intended side effect of making sure that
"console enabled:" messages are printed on the bootconsole, and
the real console. This does cause the same line is printed
twice if the bootconsole and real console are the same device,
but if they are on different devices, the message is printed to
both consoles.

Signed-off-by : Robin Getz <rgetz@blackfin.uclinux.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>
LKML-Reference: <200907091308.37370.rgetz@blackfin.uclinux.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-10 12:24:47 +02:00
Robin Getz 4d09161196 printk: Enable the use of more than one CON_BOOT (early console)
Today, register_console() assumes the following usage:

  - The first console to register with a flag set to CON_BOOT
    is the one and only bootconsole.

  - If another register_console() is called with an additional
    CON_BOOT, it is silently rejected.

  - As soon as a console without the CON_BOOT set calls
    registers the bootconsole is automatically unregistered.

  - Once there is a "real" console - register_console() will
    silently reject any consoles with it's CON_BOOT flag set.

In many systems (alpha, blackfin, microblaze, mips, powerpc,
sh, & x86), there are early_printk implementations, which use
the CON_BOOT which come out serial ports, vga, usb, & memory
buffers.

In many embedded systems, it would be nice to have two
bootconsoles - in case the primary fails, you always have
access to a backup memory buffer - but this requires at least
two CON_BOOT consoles...

This patch enables that functionality.

With the change applied, on boot you get (if you try to
re-enable a boot console after the "real" console has been
registered):

  root:/> dmesg | grep console
  bootconsole [early_shadow0] enabled
  bootconsole [early_BFuart0] enabled
  Kernel command line: root=/dev/mtdblock0 rw earlyprintk=serial,uart0,57600 console=ttyBF0,57600 nmi_debug=regs
  console handover:boot [early_BFuart0] boot [early_shadow0]  -> real [ttyBF0]
  Too late to register bootconsole early_shadow0

or:

  root:/> dmesg | grep console
  Kernel command line: root=/dev/mtdblock0 rw console=ttyBF0,57600
  console [ttyBF0] enabled

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>
Cc: "Andrew Morton" <akpm@linux-foundation.org>
Cc: "Mike Frysinger" <vapier.adi@gmail.com>
Cc: "Paul Mundt" <lethal@linux-sh.org>
LKML-Reference: <200907012108.38030.rgetz@blackfin.uclinux.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-03 10:10:43 +02:00
Linus Torvalds e28d713704 printk: Add KERN_DEFAULT printk log-level
This adds a KERN_DEFAULT loglevel marker, for when you cannot decide
which loglevel you want, and just want to keep an existing printk
with the default loglevel.

The difference between having KERN_DEFAULT and having no log-level
marker at all is two-fold:

 - having the log-level marker will now force a new-line if the
   previous printout had not added one (perhaps because it forgot,
   but perhaps because it expected a continuation)

 - having a log-level marker is required if you are printing out a
   message that otherwise itself could perhaps otherwise be mistaken
   for a log-level.

Signed-of-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16 11:02:28 -07:00
Linus Torvalds 5fd29d6ccb printk: clean up handling of log-levels and newlines
It used to be that we would only look at the log-level in a printk()
after explicit newlines, which can cause annoying problems when the
previous printk() did not end with a '\n'. In that case, the log-level
marker would be just printed out in the middle of the line, and be
seen as just noise rather than change the logging level.

This changes things to always look at the log-level in the first
bytes of the printout. If a log level marker is found, it is always
used as the log-level. Additionally, if no newline existed, one is
added (unless the log-level is the explicit KERN_CONT marker, to
explicitly show that it's a continuation of a previous line).

Acked-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-16 10:57:02 -07:00
Linus Torvalds e4c393fd55 Merge branch 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  printk: correct the behavior of printk_timed_ratelimit()
  vsprintf: unify the format decoding layer for its 3 users, cleanup
  fix regression from "vsprintf: unify the format decoding layer for its 3 users"
  vsprintf: fix bug in negative value printing
  vsprintf: unify the format decoding layer for its 3 users
  vsprintf: add binary printf
  printk: introduce printk_once()

Fix trivial conflicts (printk_once vs log_buf_kexec_setup() added near
each other) in include/linux/kernel.h.
2009-04-05 10:23:25 -07:00
Neil Horman 04d491ab2a kexec: add dmesg log symbols to /proc/vmcoreinfo lists
It would be nice to be able to extract the dmesg log from a vmcore file
without needing to keep the debug symbols for the running kernel handy all
the time.  We have a facility to do this in /proc/vmcore.  This patch adds
the log_buf and log_end symbols to the vmcoreinfo area so that tools (like
makedumpfile) can easily extract the dmesg logs from a vmcore image.

[akpm@linux-foundation.org: several fixes and cleanups]
[akpm@linux-foundation.org: fix unused log_buf_kexec_setup()]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Cc: Simon Horman <horms@verge.net.au>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Simon Horman <horms@verge.net.au>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:04 -07:00
Guillaume Knispel f2d28a2ebc printk: correct the behavior of printk_timed_ratelimit()
Impact: fix jiffies-comparison sign-wrap behavior

The behavior provided by printk_timed_ratelimit() is, in some
situations, probably not what a caller would reasonably expect:

bool printk_timed_ratelimit(unsigned long *caller_jiffies,
			unsigned int interval_msecs)
{
	if (*caller_jiffies == 0 || time_after(jiffies, *caller_jiffies)) {
		*caller_jiffies = jiffies + msecs_to_jiffies(interval_msecs);
		return true;
	}
	return false;
}

On a 32 bit computer, if printk_timed_ratelimit() is initially called at
time jiffies == Ja, *caller_jiffies is set to
Ja + msecs_to_jiffies(interval_msecs): let's say Ja + 42 for this
example.

If this caller then doesn't call printk_timed_ratelimit() until
jiffies == Ja + (1 << 31) + 42 (which can happen as soon as ~ 25 days
later on a 1000 HZ system), printk_timed_ratelimit() will then always
return false to this caller until jiffies loops completely (1 << 31 more
ticks).

Ths change makes it only return false if jiffies is in the small
time window starting at the previous call when true was returned and
ending interval_msecs later.  Note that if jiffies loops completely
between two calls to printk_timed_ratelimit(), it will obviously still
wrongly return false, but this is something with a low probability.

If something completely reliable is needed I guess jiffies_64 must be
used (which this change does not do).

Signed-off-by: Guillaume Knispel <gknispel@proformatique.com>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090317161842.0059096b@xilun.lan.proformatique.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-03-17 16:25:28 +01:00
Arve Hjønnevåg 403f307576 PM: Fix suspend_console and resume_console to use only one semaphore
This fixes a race where a thread acquires the console while the
console is suspended, and the console is resumed before this
thread releases it. In this case, the secondary console
semaphore would be left locked, and the primary semaphore would
be released twice. This in turn would cause the console switch
on suspend or resume to hang forever.

Note that suspend_console does not actually lock the console
for clients that use acquire_console_sem, it only locks it for
clients that use try_acquire_console_sem. If we change
suspend_console to fully lock the console, then the kernel
may deadlock on suspend. One client of try_acquire_console_sem
is acquire_console_semaphore_for_printk, which uses it to
prevent printk from using the console while it is suspended.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Len Brown <lenb@kernel.org>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-02-21 14:17:18 -08:00
Heiko Carstens 1e7bfb2134 [CVE-2009-0029] System call wrappers part 27
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-14 14:15:29 +01:00
Heiko Carstens f627a741d2 [CVE-2009-0029] Make sys_syslog a conditional system call
Remove the -ENOSYS implementation for !CONFIG_PRINTK and use
the cond_syscall infrastructure instead.

Acked-by: Kyle McMartin <kyle@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-14 14:15:16 +01:00
Jiri Kosina edb123e16c trivial: printk: fix indentation of new_text_line declaration
Remove bogus indentation of new_text_line declaration introduced in
commit ac60ad741.

Acked-by: Nick Andrew <nick@nick-andrew.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-01-06 11:28:06 +01:00
Hiroshi Shimamoto 26cc271db7 printk: fix discarding message when recursion_bug
Impact: fix truncated recursion bug message printout

When recursion_bug is true, kernel discards original message because printk_buf
contains recursion_bug_msg with NULL terminator. The sizeof(recursion_bug_msg)
makes this, use strlen() to get correct length without NULL terminator.

Reported-by: Toshikazu Nakayama <nakayama.ts@ncos.nec.co.jp>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-19 22:52:47 +01:00
roel kluin acff181d35 printk: remove unused code from kernel/printk.c
both log_buf_copy() and log_buf_len are unused.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-23 21:54:29 +02:00
Linus Torvalds e533b22705 Merge branch 'core-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-v28-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  do_generic_file_read: s/EINTR/EIO/ if lock_page_killable() fails
  softirq, warning fix: correct a format to avoid a warning
  softirqs, debug: preemption check
  x86, pci-hotplug, calgary / rio: fix EBDA ioremap()
  IO resources, x86: ioremap sanity check to catch mapping requests exceeding, fix
  IO resources, x86: ioremap sanity check to catch mapping requests exceeding the BAR sizes
  softlockup: Documentation/sysctl/kernel.txt: fix softlockup_thresh description
  dmi scan: warn about too early calls to dmi_check_system()
  generic: redefine resource_size_t as phys_addr_t
  generic: make PFN_PHYS explicitly return phys_addr_t
  generic: add phys_addr_t for holding physical addresses
  softirq: allocate less vectors
  IO resources: fix/remove printk
  printk: robustify printk, update comment
  printk: robustify printk, fix #2
  printk: robustify printk, fix
  printk: robustify printk

Fixed up conflicts in:
	arch/powerpc/include/asm/types.h
	arch/powerpc/platforms/Kconfig.cputype
manually.
2008-10-16 15:17:40 -07:00
Andi Kleen 20036fdcaf Add kerneldoc documentation for new printk format extensions
Add documentation in kerneldoc for new printk format extensions

This patch documents the new %pS/%pF options in printk in kernel doc.

Hope I didn't miss any other extension.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-16 11:21:32 -07:00