Split do_lookup() into two functions:
lookup_fast() - does cached lookup without i_mutex
lookup_slow() - does lookup with i_mutex
Both follow managed dentries.
The new functions are needed by atomic_open.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since we can't expect every user to read the EFI boot stub code it
seems prudent to have a couple of paragraphs explaining what it is and
how it works.
The "initrd=" option in particular is tricky because it only
understands absolute EFI-style paths (backslashes as directory
separators), and until now this hasn't been documented anywhere. This
has tripped up a couple of users.
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-4-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
We need a way of printing useful messages to the user, for example
when we fail to open an initrd file, instead of just hanging the
machine without giving the user any indication of what went wrong. So
sprinkle some error messages throughout the EFI boot stub code to make
it easier for users to diagnose/report problems.
Reported-by: Keshav P R <the.ridikulus.rat@gmail.com>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-3-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
The loop at the 'close_handles' label in handle_ramdisks() should be
using 'i', which represents the number of initrd files that were
successfully opened, not 'nr_initrds' which is the number of initrd=
arguments passed on the command line.
Currently, if we execute the loop to close all file handles and we
failed to open any initrds we'll try to call the close function on a
garbage pointer, causing the machine to hang.
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/1331907517-3985-2-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Btrfs had been doing it's own file_update_time so we could catch ENOSPC
properly, so just update our btrfs_update_time to work with the new stuff and
then we'll be fancy later. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Btrfs has to make sure we have space to allocate new blocks in order to modify
the inode, so updating time can fail. We've gotten around this by having our
own file_update_time but this is kind of a pain, and Christoph has indicated he
would like to make xfs do something different with atime updates. So introduce
->update_time, where we will deal with i_version an a/m/c time updates and
indicate which changes need to be made. The normal version just does what it
has always done, updates the time and marks the inode dirty, and then
filesystems can choose to do something different.
I've gone through all of the users of file_update_time and made them check for
errors with the exception of the fault code since it's complicated and I wasn't
quite sure what to do there, also Jan is going to be pushing the file time
updates into page_mkwrite for those who have it so that should satisfy btrfs and
make it not a big deal to check the file_update_time() return code in the
generic fault path. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
6 bytes seems to be a reasonable default so far, but for the desperate
it's worth exposing this.
[airlied: change include to module.h for this]
Bugzilla: https://bugzilla.redhat.com/582559
Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
radeon_cs_parser_init is called by both the legacy UMS
CS ioctl and the KMS CS ioctl. Protect KMS specific
pieces of the code by checking that rdev is not NULL.
Reported-by: Michael Burian <michael.burian@sbg.at>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This imbalance may cause hangs when TTM is trying to swap out a buffer
that is already on the delayed delete list.
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Tiling group size is always 256bits on r6xx/r7xx/r8xx/9xx. Also fix and
simplify render backend map. This now properly sets up the backend map
on r6xx-9xx which should improve 3D performance.
Vadim benchmarked also:
Some benchmarks on juniper (5750), fullscreen 1920x1080,
first result - kernel 3.4.0+ (fb21affa), second - with these patches:
Lightsmark: 91 fps => 123 fps +35%
Doom3: 74 fps => 101 fps +36%
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Pull btrfs updates from Chris Mason:
"This includes a fairly large change from Josef around data writeback
completion. Before, the writeback wasn't completed until the metadata
insertions for the extent were done, and this made for fairly large
latency spikes on the last page of each ordered extent.
We already had a separate mechanism for tracking pending metadata
insertions, so Josef just needed to tweak things a little to end
writeback earlier on the page. Overall it makes us much friendly to
memory reclaim and lowers latencies quite a lot for synchronous IO.
Jan Schmidt has finished some background work required to track btree
blocks as they go through changes in ownership. It's the missing
piece he needed for both btrfs send/receive and subvolume quotas.
Neither of those are ready yet, but the new tracking code is included
here. Most of the time, the new code is off. It is only used by
scrub and other backref walkers.
Stefan Behrens has added io failure tracking. This includes counters
for which drives are causing the most trouble so the admin (or an
automated tool) can choose to kick them out. We're tracking IO
errors, crc errors, and generation checks we do on each metadata
block.
RAID5/6 did miss the cut this time because I'm having trouble with
corruptions. I'll nail it down next week and post as a beta testing
before 3.6"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (58 commits)
Btrfs: fix tree mod log rewinded level and rewinding of moved keys
Btrfs: fix tree mod log del_ptr
Btrfs: add tree_mod_dont_log helper
Btrfs: add missing spin_lock for insertion into tree mod log
Btrfs: add inodes before dropping the extent lock in find_all_leafs
Btrfs: use delayed ref sequence numbers for all fs-tree updates
Btrfs: fix false positive in check-integrity on unmount
Btrfs: fix runtime warning in check-integrity check data mode
Btrfs: set ioprio of scrub readahead to idle
Btrfs: fix return code in drop_objectid_items
Btrfs: check to see if the inode is in the log before fsyncing
Btrfs: return value of btrfs_read_buffer is checked correctly
Btrfs: read device stats on mount, write modified ones during commit
Btrfs: add ioctl to get and reset the device stats
Btrfs: add device counters for detected IO and checksum errors
btrfs: Drop unused function btrfs_abort_devices()
Btrfs: fix the same inode id problem when doing auto defragment
Btrfs: fall back to non-inline if we don't have enough space
Btrfs: fix how we deal with the orphan block rsv
Btrfs: convert the inode bit field to use the actual bit operations
...
Pull the rest of the nfsd commits from Bruce Fields:
"... and then I cherry-picked the remainder of the patches from the
head of my previous branch"
This is the rest of the original nfsd branch, rebased without the
delegation stuff that I thought really needed to be redone.
I don't like rebasing things like this in general, but in this situation
this was the lesser of two evils.
* 'for-3.5' of git://linux-nfs.org/~bfields/linux: (50 commits)
nfsd4: fix, consolidate client_has_state
nfsd4: don't remove rebooted client record until confirmation
nfsd4: remove some dprintk's and a comment
nfsd4: return "real" sequence id in confirmed case
nfsd4: fix exchange_id to return confirm flag
nfsd4: clarify that renewing expired client is a bug
nfsd4: simpler ordering of setclientid_confirm checks
nfsd4: setclientid: remove pointless assignment
nfsd4: fix error return in non-matching-creds case
nfsd4: fix setclientid_confirm same_cred check
nfsd4: merge 3 setclientid cases to 2
nfsd4: pull out common code from setclientid cases
nfsd4: merge last two setclientid cases
nfsd4: setclientid/confirm comment cleanup
nfsd4: setclientid remove unnecessary terms from a logical expression
nfsd4: move rq_flavor into svc_cred
nfsd4: stricter cred comparison for setclientid/exchange_id
nfsd4: move principal name into svc_cred
nfsd4: allow removing clients not holding state
nfsd4: rearrange exchange_id logic to simplify
...
I managed to screw up the various backlight changes and ended up memsetting
the props structure after it had already been populated. This should fix it.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
This patch stops reiserfs using the VFS 'write_super()' method along with the
s_dirt flag, because they are on their way out.
The whole "superblock write-out" VFS infrastructure is served by the
'sync_supers()' kernel thread, which wakes up every 5 (by default) seconds and
writes out all dirty superblock using the '->write_super()' call-back. But the
problem with this thread is that it wastes power by waking up the system every
5 seconds, even if there are no diry superblocks, or there are no client
file-systems which would need this (e.g., btrfs does not use
'->write_super()'). So we want to kill it completely and thus, we need to make
file-systems to stop using the '->write_super()' VFS service, and then remove
it together with the kernel thread.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The 'journal_mark_dirty()' function currently first marks the superblock as
dirty by setting 's_dirt' to 1, then does various sanity checks and returns,
then actuall does all the magic with the journal.
This is not an ideal order, though. It makes more sense to first do all the
checks, then do all the internal stuff, and at the end notify the VFS that the
superblock is now dirty.
This patch moves the 's_dirt = 1' assignment from the very beginning of this
function to the very end.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The 'reiserfs_resize()' function marks the superblock as dirty by assigning 1
to 's_dirt' and then calls 'journal_mark_dirty()' which does the same. Thus,
we can remove the assignment from 'reiserfs_resize()'.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Turn 'reiserfs_flush_old_commits()' into a void function because the callers
do not cares about what it returns anyway.
We are going to remove the 'sb->s_dirt' field completely and this patch is a
small step towards this direction.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We have the reiserfs superblock pointer in the 'sbi' variable in this
function, no need to use the 'REISERFS_SB(s)' macro which is the same.
This is jut a small clean-up.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
sockfd_lookup() is declared in linux/net.h, which is pulled by
linux/skbuff.h (and needed for a lot of other stuff in sch_atm.c
anyway).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
take it to mm/util.c, convert vm_mmap() to use of that one and
take it to mm/util.c as well, convert both sys_mmap_pgoff() to
use of vm_mmap_pgoff()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
it really should be done by get_unmapped_area(); that cuts down on
the amount of callers considerably and it's the right place for
that stuff anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Need to program an additional VM register. This doesn't not currently
cause any problems, but allows us to program the proper backend
map in a subsequent patch which should improve performance on these
asics.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
While there are cards with more than 8 mem banks, the max
number of banks from a tiling perspective is 8, so cap
the tiling config at 8 banks.
Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=43448
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Once a connection is fully initialized, it is really in a CLOSED
state, so make that explicit by setting the bit in its state field.
It is possible for a connection in NEGOTIATING state to get a
failure, leading to ceph_fault() and ultimately ceph_con_close().
Clear that bits if it is set in that case, to reflect that the
connection truly is closed and is no longer participating in a
connect sequence.
Issue a warning if ceph_con_open() is called on a connection that
is not in CLOSED state.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Pass the osd number to the create_osd() routine, and move the
initialization of fields that depend on it therein.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Start explicitly keeping track of the state of a ceph connection's
socket, separate from the state of the connection itself. Create
placeholder functions to encapsulate the state transitions.
--------
| NEW* | transient initial state
--------
| con_sock_state_init()
v
----------
| CLOSED | initialized, but no socket (and no
---------- TCP connection)
^ \
| \ con_sock_state_connecting()
| ----------------------
| \
+ con_sock_state_closed() \
|\ \
| \ \
| ----------- \
| | CLOSING | socket event; \
| ----------- await close \
| ^ |
| | |
| + con_sock_state_closing() |
| / \ |
| / --------------- |
| / \ v
| / --------------
| / -----------------| CONNECTING | socket created, TCP
| | / -------------- connect initiated
| | | con_sock_state_connected()
| | v
-------------
| CONNECTED | TCP connection established
-------------
Make the socket state an atomic variable, reinforcing that it's a
distinct transtion with no possible "intermediate/both" states.
This is almost certainly overkill at this point, though the
transitions into CONNECTED and CLOSING state do get called via
socket callback (the rest of the transitions occur with the
connection mutex held). We can back out the atomicity later.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil<sage@inktank.com>
A ceph_connection holds a mixture of connection state (as in "state
machine" state) and connection flags in a single "state" field. To
make the distinction more clear, define a new "flags" field and use
it rather than the "state" field to hold Boolean flag values.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil<sage@inktank.com>
A ceph client has a pointer to a ceph messenger structure in it.
There is always exactly one ceph messenger for a ceph client, so
there is no need to allocate it separate from the ceph client
structure.
Switch the ceph_client structure to embed its ceph_messenger
structure.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
The functions ceph_con_out_kvec_reset() and ceph_con_out_kvec_add()
are entirely private functions, so drop the "ceph_" prefix in their
name to make them slightly more wieldy.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Change the names of the three socket callback functions to make it
more obvious they're specifically associated with a connection's
socket (not the ceph connection that uses it).
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
No code sets a bad_proto method in its ceph connection operations
vector, so just get rid of it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
The ceph connection state "DEAD" is never set and is therefore not
needed. Eliminate it.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
I got lots of NULL pointer dereference Oops when compiling kernel on ceph.
The bug is because the kernel page migration routine replaces some pages
in the page cache with new pages, these new pages' private can be non-zero.
Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: Sage Weil <sage@inktank.com>
It appears grub2 can pass framebuffer info via efifb, so
we need to kick it off earlier to reserve the vram allocation.
(just a fixup same as for cirrus)
Signed-off-by: Dave Airlie <airlied@redhat.com>
It appears that grub2 will pass framebuffer info via EFI,
this causes the vram reserve to fail, so kick out efifb
earlier before cirrus loads.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=826983
Signed-off-by: Dave Airlie <airlied@redhat.com>
When truncating a file, we unmap pages from userspace first, as that's
usually more efficient than relying, page by page, on the fallback in
truncate_inode_page() - particularly if the file is mapped many times.
Do the same when punching a hole: 3.4 added truncate_pagecache_range()
to do the unmap and trunc, so use it in ext4_ext_punch_hole(), instead
of calling truncate_inode_pages_range() directly.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Use kmem_cache_zalloc wrapper instead of flag __GFP_ZERO.
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We can't have references held on pages in the s_buddy_cache while we are
trying to truncate its pages and put the inode. All the pages must be
gone before we reach clear_inode. This can only be gauranteed if we
can prevent new users from grabbing references to s_buddy_cache's pages.
The original bug can be reproduced and the bug fix can be verified by:
while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
umount /export/hda3/ram0; done &
while true; do cat /proc/fs/ext4/ram0/mb_groups; done
Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
ext4_free_blocks fails to pair an ext4_mb_load_buddy with a matching
ext4_mb_unload_buddy when it fails a memory allocation.
Signed-off-by: Salman Qazi <sqazi@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
In commit 353eb83c we removed i_state_flags with 64-bit longs, But
when handling the EXT4_IOC_SETFLAGS ioctl, we replace i_flags
directly, which trashes the state flags which are stored in the high
32-bits of i_flags on 64-bit platforms. So use the the
ext4_{set,clear}_inode_flags() functions which use atomic bit
manipulation functions instead.
Reported-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
When both DYNAMIC_FTRACE and LOCKDEP are set, the TRACE_IRQS_ON/OFF
will call into the lockdep code. The lockdep code can call lots of
functions that may be traced by ftrace. When ftrace is updating its
code and hits a breakpoint, the breakpoint handler will call into
lockdep. If lockdep happens to call a function that also has a breakpoint
attached, it will jump back into the breakpoint handler resetting
the stack to the debug stack and corrupt the contents currently on
that stack.
The 'do_sym' call that calls do_int3() is protected by modifying the
IST table to point to a different location if another breakpoint is
hit. But the TRACE_IRQS_OFF/ON are outside that protection, and if
a breakpoint is hit from those, the stack will get corrupted, and
the kernel will crash:
[ 1013.243754] BUG: unable to handle kernel NULL pointer dereference at 0000000000000002
[ 1013.272665] IP: [<ffff880145cc0000>] 0xffff880145cbffff
[ 1013.285186] PGD 1401b2067 PUD 14324c067 PMD 0
[ 1013.298832] Oops: 0010 [#1] PREEMPT SMP
[ 1013.310600] CPU 2
[ 1013.317904] Modules linked in: ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables crc32c_intel ghash_clmulni_intel microcode usb_debug serio_raw pcspkr iTCO_wdt i2c_i801 iTCO_vendor_support e1000e nfsd nfs_acl auth_rpcgss lockd sunrpc i915 video i2c_algo_bit drm_kms_helper drm i2c_core [last unloaded: scsi_wait_scan]
[ 1013.401848]
[ 1013.407399] Pid: 112, comm: kworker/2:1 Not tainted 3.4.0+ #30
[ 1013.437943] RIP: 8eb8:[<ffff88014630a000>] [<ffff88014630a000>] 0xffff880146309fff
[ 1013.459871] RSP: ffffffff8165e919:ffff88014780f408 EFLAGS: 00010046
[ 1013.477909] RAX: 0000000000000001 RBX: ffffffff81104020 RCX: 0000000000000000
[ 1013.499458] RDX: ffff880148008ea8 RSI: ffffffff8131ef40 RDI: ffffffff82203b20
[ 1013.521612] RBP: ffffffff81005751 R08: 0000000000000000 R09: 0000000000000000
[ 1013.543121] R10: ffffffff82cdc318 R11: 0000000000000000 R12: ffff880145cc0000
[ 1013.564614] R13: ffff880148008eb8 R14: 0000000000000002 R15: ffff88014780cb40
[ 1013.586108] FS: 0000000000000000(0000) GS:ffff880148000000(0000) knlGS:0000000000000000
[ 1013.609458] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 1013.627420] CR2: 0000000000000002 CR3: 0000000141f10000 CR4: 00000000001407e0
[ 1013.649051] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1013.670724] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 1013.692376] Process kworker/2:1 (pid: 112, threadinfo ffff88013fe0e000, task ffff88014020a6a0)
[ 1013.717028] Stack:
[ 1013.724131] ffff88014780f570 ffff880145cc0000 0000400000004000 0000000000000000
[ 1013.745918] cccccccccccccccc ffff88014780cca8 ffffffff811072bb ffffffff81651627
[ 1013.767870] ffffffff8118f8a7 ffffffff811072bb ffffffff81f2b6c5 ffffffff81f11bdb
[ 1013.790021] Call Trace:
[ 1013.800701] Code: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a <e7> d7 64 81 ff ff ff ff 01 00 00 00 00 00 00 00 65 d9 64 81 ff
[ 1013.861443] RIP [<ffff88014630a000>] 0xffff880146309fff
[ 1013.884466] RSP <ffff88014780f408>
[ 1013.901507] CR2: 0000000000000002
The solution was to reuse the NMI functions that change the IDT table to make the debug
stack keep its current stack (in kernel mode) when hitting a breakpoint:
call debug_stack_set_zero
TRACE_IRQS_ON
call debug_stack_reset
If the TRACE_IRQS_ON happens to hit a breakpoint then it will keep the current stack
and not crash the box.
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When the NMI handler runs, it checks if it preempted a debug handler
and if that handler is using the debug stack. If it is, it changes the
IDT table not to update the stack, otherwise it will reset the debug
stack and corrupt the debug handler it preempted.
Now that ftrace uses breakpoints to change functions from nops to
callers, many more places may hit a breakpoint. Unfortunately this
includes some of the calls that lockdep performs. Which causes issues
with the debug stack. It too needs to change the debug stack before
tracing (if called from the debug handler).
Allow the debug_stack_set_zero() and debug_stack_reset() to be nested
so that the debug handlers can take advantage of them too.
[ Used this_cpu_*() over __get_cpu_var() as suggested by H. Peter Anvin ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
When an NMI goes off and it sees that it preempted the debug stack,
to keep the debug stack safe, it changes the IDT to point to one that
does not modify the stack on breakpoint (to allow breakpoints in NMIs).
But the variable that gets set to know to undo it on exit never gets
cleared on exit. Thus every NMI will reset it on exit the first time
it is done even if it does not need to be reset.
[ Added H. Peter Anvin's suggestion to use this_cpu_read/write ]
Cc: <stable@vger.kernel.org> # v3.3
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Miklos Szeredi