This file seeks to explain the nuances in various delays;
many driver writers are not necessarily familiar with the
various kernel timers, their shortfalls, and quirks. When
faced with
ndelay, udelay, mdelay, usleep_range, msleep, and msleep_interrubtible
the question "How do I just wait 1 ms for my hardware to
latch?" has the non-intuitive "best" answer:
usleep_range(1000,1500)
This patch is followed by a series of checkpatch additions
that seek to help kernel hackers pick the best delay.
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: apw@canonical.com
Cc: corbet@lwn.net
Cc: arjan@linux.intel.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1280786467-26999-3-git-send-email-ppannuto@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
usleep_range is a finer precision implementations of msleep
and is designed to be a drop-in replacement for udelay where
a precise sleep / busy-wait is unnecessary.
Since an easy interface to hrtimers could lead to an undesired
proliferation of interrupts, we provide only a "range" API,
forcing the caller to think about an acceptable tolerance on
both ends and hopefully avoiding introducing another interrupt.
INTRO
As discussed here ( http://lkml.org/lkml/2007/8/3/250 ), msleep(1) is not
precise enough for many drivers (yes, sleep precision is an unfair notion,
but consistently sleeping for ~an order of magnitude greater than requested
is worth fixing). This patch adds a usleep API so that udelay does not have
to be used. Obviously not every udelay can be replaced (those in atomic
contexts or being used for simple bitbanging come to mind), but there are
many, many examples of
mydriver_write(...)
/* Wait for hardware to latch */
udelay(100)
in various drivers where a busy-wait loop is neither beneficial nor
necessary, but msleep simply does not provide enough precision and people
are using a busy-wait loop instead.
CONCERNS FROM THE RFC
Why is udelay a problem / necessary? Most callers of udelay are in device/
driver initialization code, which is serial...
As I see it, there is only benefit to sleeping over a delay; the
notion of "refactoring" areas that use udelay was presented, but
I see usleep as the refactoring. Consider i2c, if the bus is busy,
you need to wait a bit (say 100us) before trying again, your
current options are:
* udelay(100)
* msleep(1) <-- As noted above, actually as high as ~20ms
on some platforms, so not really an option
* Manually set up an hrtimer to try again in 100us (which
is what usleep does anyway...)
People choose the udelay route because it is EASY; we need to
provide a better easy route.
Device / driver / boot code is *currently* serial, but every few
months someone makes noise about parallelizing boot, and IMHO, a
little forward-thinking now is one less thing to worry about
if/when that ever happens
udelay's could be preempted
Sure, but if udelay plans on looping 1000 times, and it gets
preempted on loop 200, whenever it's scheduled again, it is
going to do the next 800 loops.
Is the interruptible case needed?
Probably not, but I see usleep as a very logical parallel to msleep,
so it made sense to include the "full" API. Processors are getting
faster (albeit not as quickly as they are becoming more parallel),
so if someone wanted to be interruptible for a few usecs, why not
let them? If this is a contentious point, I'm happy to remove it.
OTHER THOUGHTS
I believe there is also value in exposing the usleep_range option; it gives
the scheduler a lot more flexibility and allows the programmer to express
his intent much more clearly; it's something I would hope future driver
writers will take advantage of.
To get the results in the NUMBERS section below, I literally s/udelay/usleep
the kernel tree; I had to go in and undo the changes to the USB drivers, but
everything else booted successfully; I find that extremely telling in and
of itself -- many people are using a delay API where a sleep will suit them
just fine.
SOME ATTEMPTS AT NUMBERS
It turns out that calculating quantifiable benefit on this is challenging,
so instead I will simply present the current state of things, and I hope
this to be sufficient:
How many udelay calls are there in 2.6.35-rc5?
udealy(ARG) >= | COUNT
1000 | 319
500 | 414
100 | 1146
20 | 1832
I am working on Android, so that is my focus for this. The following table
is a modified usleep that simply printk's the amount of time requested to
sleep; these tests were run on a kernel with udelay >= 20 --> usleep
"boot" is power-on to lock screen
"power collapse" is when the power button is pushed and the device suspends
"resume" is when the power button is pushed and the lock screen is displayed
(no touchscreen events or anything, just turning on the display)
"use device" is from the unlock swipe to clicking around a bit; there is no
sd card in this phone, so fail loading music, video, camera
ACTION | TOTAL NUMBER OF USLEEP CALLS | NET TIME (us)
boot | 22 | 1250
power-collapse | 9 | 1200
resume | 5 | 500
use device | 59 | 7700
The most interesting category to me is the "use device" field; 7700us of
busy-wait time that could be put towards better responsiveness, or at the
least less power usage.
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: apw@canonical.com
Cc: corbet@lwn.net
Cc: arjan@linux.intel.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Historically, Linux has tried to make the regular timer tick on the
various CPUs not happen at the same time, to avoid contention on
xtime_lock.
Nowadays, with the tickless kernel, this contention no longer happens
since time keeping and updating are done differently. In addition,
this skew is actually hurting power consumption in a measurable way on
many-core systems.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100727210210.58d3118c@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
According to Oleg Nesterov:
We can move copy_to_user(created_timer_id) down after
"if (timer_event_spec)" block too. (but before CLOCK_DISPATCH(),
of course).
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
usleep[_range] are finer precision implementations of msleep
and are designed to be drop-in replacements for udelay where
a precise sleep / busy-wait is unnecessary. They also allow
an easy interface to specify slack when a precise (ish)
wakeup is unnecessary to help minimize wakeups
Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
Cc: akinobu.mita@gmail.com
Cc: sboyd@codeaurora.org
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <4C44CDD2.1070708@codeaurora.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Steal some text from 6e453a6751 "Add support for deferrable timers". A
reader shouldn't have to dig through the git logs for the basic
description of a deferrable timer.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: johnstul@us.ibm.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: synaptics - relax capability ID checks on newer hardware
Input: twl40300-keypad - fix handling of "all ground" rows
Input: gamecon - reference correct pad in gc_psx_command()
Input: gamecon - reference correct input device in NES mode
Input: w90p910_keypad - change platfrom driver name to 'nuc900-kpi'
Input: i8042 - add Gigabyte Spring Peak to dmi_noloop_table
Input: qt2160 - rename kconfig symbol name
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/radeon/kms: add quirk to make HP DV5000 laptop resume
drm/radeon/kms: fix RADEON_INFO_CRTC_FROM_ID info ioctl
Fix ttm_page_alloc.c build breakage
drm/radeon/kms: fix legacy LVDS dpms sequence
drm/radeon/kms: drop taking lock around crtc lookup.
* 'x86/auditsyscall' of git://git.kernel.org/pub/scm/linux/kernel/git/frob/linux-2.6-roland:
x86: auditsyscall: fix fastpath return value after reschedule
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
sysrq,kdb: Use __handle_sysrq() for kdb's sysrq function
debug_core,kdb: fix kgdb_connected bit set in the wrong place
Fix merge regression from external kdb to upstream kdb
repair gdbstub to match the gdbserial protocol specification
kdb: break out of kdb_ll() when command is terminated
Fix the security problem in the CIFS filesystem DNS lookup code in which a
malicious redirect could be installed by a random user by simply adding a
result record into one of their keyrings with add_key() and then invoking a
CIFS CFS lookup [CVE-2010-2524].
This is done by creating an internal keyring specifically for the caching of
DNS lookups. To enforce the use of this keyring, the module init routine
creates a set of override credentials with the keyring installed as the thread
keyring and instructs request_key() to only install lookup result keys in that
keyring.
The override is then applied around the call to request_key().
This has some additional benefits when a kernel service uses this module to
request a key:
(1) The result keys are owned by root, not the user that caused the lookup.
(2) The result keys don't pop up in the user's keyrings.
(3) The result keys don't come out of the quota of the user that caused the
lookup.
The keyring can be viewed as root by doing cat /proc/keys:
2a0ca6c3 I----- 1 perm 1f030000 0 0 keyring .dns_resolver: 1/4
It can then be listed with 'keyctl list' by root.
# keyctl list 0x2a0ca6c3
1 key in keyring:
726766307: --alswrv 0 0 dns_resolver: foo.bar.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-Tested-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve French <smfrench@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=29062
Reported-by: Andres Cimmarusti <acimmarusti@gmail.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Older firmwares fixed the middle byte of the Synaptics capabilities
query to 0x47, but starting with firmware 7.5 the middle byte
represents submodel ID, sometimes also called "dash number".
Reported-and-tested-by: Miroslav Šulc <fordfrog@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
In the CONFIG_AUDITSYSCALL fast-path for x86 64-bit system calls,
we can pass a bad return value and/or error indication for the
system call to audit_syscall_exit(). This happens when
TIF_NEED_RESCHED was set as the system call returned, so we went
out to schedule() and came back to the exit-audit fast-path. The
fix is to reload the user return value register from the pt_regs
before using it for audit_syscall_exit().
Both the 32-bit kernel's fast path and the 64-bit kernel's 32-bit
system call fast paths work slightly differently, so that they
always leave the fast path entirely to reschedule and don't return
there, so they don't have the analogous bugs.
Reported-by: Alexander Viro <aviro@redhat.com>
Signed-off-by: Roland McGrath <roland@redhat.com>
The kdb code should not toggle the sysrq state in case an end user
wants to try and resume the normal kernel execution.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Immediately following an exit from the kdb shell the kgdb_connected
variable should be set to zero, unless there are breakpoints planted.
If the kgdb_connected variable is not zeroed out with kdb, it is
impossible to turn off kdb.
This patch is merely a work around for now, the real fix will check
for the breakpoints.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
In the process of merging kdb to the mainline, the kdb lsmod command
stopped printing the base load address of kernel modules. This is
needed for using kdb in conjunction with external tools such as gdb.
Simply restore the functionality by adding a kdb_printf for the base
load address of the kernel modules.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.
The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.
The incorrect response from the gdbstub leads the debugger clients to
not function correctly. Recent versions of gdb will not detach correctly as a result of this behavior.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Without this patch the "ll" linked-list traversal command won't
terminate when you hit q/Q.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Return the crtc_id, not the counter value. They are not
necessarily the same.
Cc: Jerome Glisse <glisse@freedesktop.org>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
The commit 1e8655f873
drm/ttm: Fix build on architectures without AGP
looks at TTM_HAS_AGP before it has been set in ttm_bo_driver.h
Move the conditional inclusion of <asm/agp.h> *after* we have included
ttm_bo_driver.h
Signed-of-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Add delay after turning off the LVDS encoder.
Fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=16389
Tested-by: Jan Kreuzer <kontrollator@gmx.de>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
We only add/remove crtcs at driver load, you cannot remove when
the GPU is running a CS packet since the fd is open, when
GPU hotplugging on radeons actually is needed all this locking
needs a review and I've started re-working kms core locking to deal
with this better. But for now avoid long delays in CS processing when
hotplug detect is happening in a different thread.
this fixes a regression introduced with hotplug detection.
Signed-off-by: Dave Airlie <airlied@redhat.com>
* 'fix/asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ASoC: Select wm_hubs automatically for WM8994
ASoC: Remove duplicate AUX definition from WM8776
ASoC:: remove a redundant snd_soc_unregister_codec call in wm8988_register
ASoC: wm8727: add a missing return in wm8727_platform_probe
ASoC: fsi: fixup wrong value setting order of TDM
ASoC: fsi: fixup clock inversion operation
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
math-emu: correct test for downshifting fraction in _FP_FROM_INT()
perf: Add DWARF register lookup for sparc
MAINTAINERS: Add SBUS driver path to sparc entry.
drivers/sbus: Remove unnecessary casts of private_data
sparc: remove homegrown L1_CACHE_ALIGN macro
sparc64: fix the build error due to smp_kgdb_capture_client()
sparc64: Fix maybe_change_configuration() PCR setting.
arch/sparc/kernel: Eliminate what looks like a NULL pointer dereference
sparc64: Update defconfig.
sunsu: Fix use after free in su_remove().
sunserial: Don't call add_preferred_console() when console= is specified.
sparc32: Kill none_mask, it's bogus.
Pointed out by Lucas who found the new one in a comment in
setup_percpu.c. And then I fixed the others that I grepped
for.
Reported-by: Lucas <canolucas@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Up to 2.6.34 pcmcia_release_irq() reset p_dev->_irq to 0 after releasing
the irq. The IRQ is now released in pcmcia_disable_device(), however
p_dev->_irq is not reset, triggering a warning in pcmcia_device_remove().
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Add the shrinkers missed in the first conversion of the API in
commit 7f8275d0d6 ("mm: add context argument to
shrinker callback").
Signed-off-by: Dave Chinner <dchinner@redhat.com>
The Nokia RX51 board code (arch/arm/mach-omap2/board-rx51-peripherals.c)
defines a key map for the matrix keypad keyboard. The hardware seems to
use all of the 8 rows and 8 columns of the keypad, although not all
possible locations are used.
The TWL4030 supports keypads with at most 8 rows and 8 columns. Most keys
are defined with a row and column number between 0 and 7, except
KEY(0xff, 2, KEY_F9),
KEY(0xff, 4, KEY_F10),
KEY(0xff, 5, KEY_F11),
which represent keycodes that should be emitted when entire row is
connected to the ground. since the driver handles this case as if we
had an extra column in the key matrix. Unfortunately we do not allocate
enough space and end up owerwriting some random memory.
Reported-and-tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: stable@kernel.org
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
We moved input devices from 'struct gc' to individial pads (struct
gc-pad), but gc_nes_process_packet() was still trying to use old
ones and crashing.
Cc: stable@kernel.org
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
The kernel's math-emu code contains a macro _FP_FROM_INT() which is
used to convert an integer to a raw normalized floating-point value.
It does this basically in three steps:
1. Compute the exponent from the number of leading zero bits.
2. Downshift large fractions to put the MSB in the right position
for normalized fractions.
3. Upshift small fractions to put the MSB in the right position.
There is an boundary error in step 2, causing a fraction with its
MSB exactly one bit above the normalized MSB position to not be
downshifted. This results in a non-normalized raw float, which when
packed becomes a massively inaccurate representation for that input.
The impact of this depends on a number of arch-specific factors,
but it is known to have broken emulation of FXTOD instructions
on UltraSPARC III, which was originally reported as GCC bug 44631
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44631>.
Any arch which uses math-emu to emulate conversions from integers to
same-size floats may be affected.
The fix is simple: the exponent comparison used to determine if the
fraction should be downshifted must be "<=" not "<".
I'm sending a kernel module to test this as a reply to this message.
There are also SPARC user-space test cases in the GCC bug entry.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/r600: fix possible NULL pointer derefernce
drm/radeon/kms: add quirk for ASUS HD 3600 board
include/linux/vgaarb.h: add missing part of include guard
drm/nouveau: Fix crashes during fbcon init on single head cards.
drm/nouveau: fix pcirom vbios shadow breakage from acpi rom patch
drm/radeon/kms: fix shared ddc harder
drm/i915: enable low power render writes on GEN3 hardware.
drm/i915: Define MI_ARB_STATE bits
vmwgfx: return -EFAULT if copy_to_user fails
fb: handle allocation failure in alloc_apertures()
drm: radeon: check kzalloc() result
drm/ttm: Fix build on architectures without AGP
drm/radeon/kms: fix gtt MC base alignment on rs4xx/rs690/rs740 asics
drm/radeon/kms: fix possible mis-detection of sideport on rs690/rs740
drm/radeon/kms: fix legacy tv-out pal mode
Reported-by: Alexander Y. Fomichev <git.user@gmail.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Connector is actually DVI rather than HDMI.
Reported-by: trapDoor <trapdoor6@gmail.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
vgaarb.h was missing the #define of the #ifndef at the top for the guard
to prevent multiple #include's from causing re-define errors
Signed-off-by: Doug Goldstein <cardoe@gentoo.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
ceph: do not include cap/dentry releases in replayed messages
ceph: reuse request message when replaying against recovering mds
ceph: fix creation of ipv6 sockets
ceph: fix parsing of ipv6 addresses
ceph: fix printing of ipv6 addrs
ceph: add kfree() to error path
ceph: fix leak of mon authorizer
ceph: fix message revocation
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (24 commits)
bridge: Partially disable netpoll support
tcp: fix crash in tcp_xmit_retransmit_queue
IPv6: fix CoA check in RH2 input handler (mip6_rthdr_input())
ibmveth: lost IRQ while closing/opening device leads to service loss
rt2x00: Fix lockdep warning in rt2x00lib_probe_dev()
vhost: avoid pr_err on condition guest can trigger
ipmr: Don't leak memory if fib lookup fails.
vhost-net: avoid flush under lock
net: fix problem in reading sock TX queue
net/core: neighbour update Oops
net: skb_tx_hash() fix relative to skb_orphan_try()
rfs: call sock_rps_record_flow() in tcp_splice_read()
xfrm: do not assume that template resolving always returns xfrms
hostap_pci: set dev->base_addr during probe
axnet_cs: use spin_lock_irqsave in ax_interrupt
dsa: Fix Kconfig dependencies.
act_nat: not all of the ICMP packets need an IP header payload
r8169: incorrect identifier for a 8168dp
Phonet: fix skb leak in pipe endpoint accept()
Bluetooth: Update sec_level/auth_type for already existing connections
...
If a single-threaded process does a file-descriptor operation, and some
other process accesses that same file descriptor via /proc, the current
rcu_dereference_check_fdtable() can give a false-positive RCU-lockdep
splat due to the reference count being increased by the /proc access after
the reference-count check in fget_light() but before the check in
rcu_dereference_check_fdtable().
This commit prevents this false positive by checking for a single-threaded
process. To avoid #include hell, this commit uses the wrapper for
thread_group_empty(current) defined by rcu_my_thread_group_empty()
provided in a separate commit.
Located-by: Miles Lane <miles.lane@gmail.com>
Located-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
System will crash sooner or later once the memory with the code of the
s3c-sdhci.ko module is reused for something else. I really have no idea
how the lack of remove function went unnoticed into the mainline code.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
My Collabora address is no longer enabled - update the MODULE_AUTHOR
fields of drivers to my current email address.
Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit e534c7c5f8 ("numa: x86_64: use generic percpu var
numa_node_id() implementation") broke numa systems that don't have ram
on node0 when MEMORY_HOTPLUG is enabled, because cpu_up() will call
cpu_to_node() before per_cpu(numa_node) is setup for APs.
When Node0 doesn't have RAM, on x86, cpus already round it to nearest
node with RAM in x86_cpu_to_node_map. and per_cpu(numa_node) is not set
up until in c_init for APs.
When later cpu_up() calling cpu_to_node() will get 0 again, and make it
online even there is no RAM on node0. so later all APs can not booted up,
and later will have panic.
[ 1.611101] On node 0 totalpages: 0
.........
[ 2.608558] On node 0 totalpages: 0
[ 2.612065] Brought up 1 CPUs
[ 2.615199] Total of 1 processors activated (3990.31 BogoMIPS).
...
93.225341] calling loop_init+0x0/0x1a4 @ 1
[ 93.229314] PERCPU: allocation failed, size=80 align=8, failed to populate
[ 93.246539] Pid: 1, comm: swapper Tainted: G W 2.6.35-rc4-tip-yh-04371-gd64e6c4-dirty #354
[ 93.264621] Call Trace:
[ 93.266533] [<ffffffff81125e43>] pcpu_alloc+0x83a/0x8e7
[ 93.270710] [<ffffffff81125f15>] __alloc_percpu+0x10/0x12
[ 93.285849] [<ffffffff8140786c>] alloc_disk_node+0x94/0x16d
[ 93.291811] [<ffffffff81407956>] alloc_disk+0x11/0x13
[ 93.306157] [<ffffffff81503e51>] loop_alloc+0xa7/0x180
[ 93.310538] [<ffffffff8277ef48>] loop_init+0x9b/0x1a4
[ 93.324909] [<ffffffff8277eead>] ? loop_init+0x0/0x1a4
[ 93.329650] [<ffffffff810001f2>] do_one_initcall+0x57/0x136
[ 93.345197] [<ffffffff827486d0>] kernel_init+0x184/0x20e
[ 93.348146] [<ffffffff81034954>] kernel_thread_helper+0x4/0x10
[ 93.365194] [<ffffffff81c7cc3c>] ? restore_args+0x0/0x30
[ 93.369305] [<ffffffff8274854c>] ? kernel_init+0x0/0x20e
[ 93.386011] [<ffffffff81034950>] ? kernel_thread_helper+0x0/0x10
[ 93.392047] loop: out of memory
...
Try to assign per_cpu(numa_node) early
[akpm@linux-foundation.org: tidy up code comment]
Signed-off-by: Yinghai <yinghai@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Simply add a proper ID into the device table.
Signed-off-by: Anton Vorontsov <avorontsov@mvista.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Dave Jiang <djiang@mvista.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patrick Pannuto