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  1. 20 May, 2015 4 commits
    • Ming Lei's avatar
      block: loop: don't hold lo_ctl_mutex in lo_open · f8933667
      Ming Lei authored 
      The lo_ctl_mutex is held for running all ioctl handlers, and
in some ioctl handlers, ioctl_by_bdev(BLKRRPART) is called for
rereading partitions, which requires bd_mutex.

So it is easy to cause failure because trylock(bd_mutex) may
fail inside blkdev_reread_part(), and follows the lock context:

blkid or other application:
	->open()
		->mutex_lock(bd_mutex)
		->lo_open()
			->mutex_lock(lo_ctl_mutex)

losetup(set fd ioctl):
	->mutex_lock(lo_ctl_mutex)
	->ioctl_by_bdev(BLKRRPART)
		->trylock(bd_mutex)

This patch trys to eliminate the ABBA lock dependency by removing
lo_ctl_mutext in lo_open() with the following approach:

1) make lo_refcnt as atomic_t and avoid acquiring lo_ctl_mutex in lo_open():
	- for open vs. add/del loop, no any problem because of loop_index_mutex
	- freeze request queue during clr_fd, so I/O can't come until
	  clearing fd is completed, like the effect of holding lo_ctl_mutex
	  in lo_open
	- both open() and release() have been serialized by bd_mutex already

2) don't hold lo_ctl_mutex for decreasing/checking lo_refcnt in
lo_release(), then lo_ctl_mutex is only required for the last release.
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarJarod Wilson <jarod@redhat.com>
Acked-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      f8933667
    • Jens Axboe's avatar
      Merge branch 'for-4.2/core' into for-4.2/drivers · b816d45f
      Jens Axboe authored 
      We need the blkdev_reread_part() changes for drivers to adapt.
      b816d45f
    • Ming Lei's avatar
      block: replace trylock with mutex_lock in blkdev_reread_part() · b04a5636
      Ming Lei authored 
      The only possible problem of using mutex_lock() instead of trylock
is about deadlock.

If there aren't any locks held before calling blkdev_reread_part(),
deadlock can't be caused by this conversion.

If there are locks held before calling blkdev_reread_part(),
and if these locks arn't required in open, close handler and I/O
path, deadlock shouldn't be caused too.

Both user space's ioctl(BLKRRPART) and md_setup_drive() from
init/do_mounts_md.c belongs to the 1st case, so the conversion is safe
for the two cases.

For loop, the previous patches in this pathset has fixed the ABBA lock
dependency, so the conversion is OK.

For nbd, tx_lock is held when calling the function:

	- both open and release won't hold the lock
	- when blkdev_reread_part() is run, I/O thread has been stopped
	already, so tx_lock won't be acquired in I/O path at that time.
	- so the conversion won't cause deadlock for nbd

For dasd, both dasd_open(), dasd_release() and request function don't
acquire any mutex/semphone, so the conversion should be safe.
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarJarod Wilson <jarod@redhat.com>
Acked-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      b04a5636
    • Jarod Wilson's avatar
      block: export blkdev_reread_part() and __blkdev_reread_part() · be324177
      Jarod Wilson authored 
      This patch exports blkdev_reread_part() for block drivers, also
introduce __blkdev_reread_part().

For some drivers, such as loop, reread of partitions can be run
from the release path, and bd_mutex may already be held prior to
calling ioctl_by_bdev(bdev, BLKRRPART, 0), so introduce
__blkdev_reread_part for use in such cases.

CC: Christoph Hellwig <hch@lst.de>
CC: Jens Axboe <axboe@kernel.dk>
CC: Tejun Heo <tj@kernel.org>
CC: Alexander Viro <viro@zeniv.linux.org.uk>
CC: Markus Pargmann <mpa@pengutronix.de>
CC: Stefan Weinhuber <wein@de.ibm.com>
CC: Stefan Haberland <stefan.haberland@de.ibm.com>
CC: Sebastian Ott <sebott@linux.vnet.ibm.com>
CC: Fabian Frederick <fabf@skynet.be>
CC: Ming Lei <ming.lei@canonical.com>
CC: David Herrmann <dh.herrmann@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: nbd-general@lists.sourceforge.net
CC: linux-s390@vger.kernel.org
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJarod Wilson <jarod@redhat.com>
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      be324177
  3. 19 May, 2015 6 commits
  5. 18 May, 2015 2 commits
  7. 08 May, 2015 6 commits
    • Shaohua Li's avatar
      blk-mq: make plug work for mutiple disks and queues · 5b3f341f
      Shaohua Li authored 
      Last patch makes plug work for multiple queue case. However it only
works for single disk case, because it assumes only one request in the
plug list. If a task is accessing multiple disks, eg MD/DM, the
assumption is wrong. Let blk_attempt_plug_merge() record request from
the same queue.

V2: use NULL parameter in !mq case. Fix a bug. Add comments in
blk_attempt_plug_merge to make it less (hopefully) confusion.

Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5b3f341f
    • Shaohua Li's avatar
      blk-mq: do limited block plug for multiple queue case · f984df1f
      Shaohua Li authored 
      plug is still helpful for workload with IO merge, but it can be harmful
otherwise especially with multiple hardware queues, as there is
(supposed) no lock contention in this case and plug can introduce
latency. For multiple queues, we do limited plug, eg plug only if there
is request merge. If a request doesn't have merge with following
request, the requet will be dispatched immediately.

V2: check blk_queue_nomerges() as suggested by Jeff.

Cc: Jens Axboe <axboe@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      f984df1f
    • Shaohua Li's avatar
      blk-mq: avoid re-initialize request which is failed in direct dispatch · 239ad215
      Shaohua Li authored 
      If we directly issue a request and it fails, we use
blk_mq_merge_queue_io(). But we already assigned bio to a request in
blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run
blk_mq_bio_to_request again.
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      239ad215
    • Jeff Moyer's avatar
      blk-mq: fix plugging in blk_sq_make_request · e6c4438b
      Jeff Moyer authored 
      The following appears in blk_sq_make_request:

	/*
	 * If we have multiple hardware queues, just go directly to
	 * one of those for sync IO.
	 */

We clearly don't have multiple hardware queues, here!  This comment was
introduced with this commit 07068d5b (blk-mq: split make request
handler for multi and single queue):

    We want slightly different behavior from them:

    - On single queue devices, we currently use the per-process plug
      for deferred IO and for merging.

    - On multi queue devices, we don't use the per-process plug, but
      we want to go straight to hardware for SYNC IO.

The old code had this:

        use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);

and that was converted to:

	use_plug = !is_flush_fua && !is_sync;

which is not equivalent.  For the single queue case, that second half of
the && expression is always true.  So, what I think was actually inteded
follows (and this more closely matches what is done in blk_queue_bio).

V2: delete the 'likely', which should not be a big deal
Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      e6c4438b
    • Shaohua Li's avatar
      sched: always use blk_schedule_flush_plug in io_schedule_out · 5596d0d5
      Shaohua Li authored 
      block plug callback could sleep, so we introduce a parameter
'from_schedule' and corresponding drivers can use it to destinguish a
schedule plug flush or a plug finish. Unfortunately io_schedule_out
still uses blk_flush_plug(). This causes below output (Note, I added a
might_sleep() in raid1_unplug to make it trigger faster, but the whole
thing doesn't matter if I add might_sleep). In raid1/10, this can cause
deadlock.

This patch makes io_schedule_out always uses blk_schedule_flush_plug.
This should only impact drivers (as far as I know, raid 1/10) which are
sensitive to the 'from_schedule' parameter.

[  370.817949] ------------[ cut here ]------------
[  370.817960] WARNING: CPU: 7 PID: 145 at ../kernel/sched/core.c:7306 __might_sleep+0x7f/0x90()
[  370.817969] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81092fcf>] prepare_to_wait+0x2f/0x90
[  370.817971] Modules linked in: raid1
[  370.817976] CPU: 7 PID: 145 Comm: kworker/u16:9 Tainted: G        W       4.0.0+ #361
[  370.817977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014
[  370.817983] Workqueue: writeback bdi_writeback_workfn (flush-9:1)
[  370.817985]  ffffffff81cd83be ffff8800ba8cb298 ffffffff819dd7af 0000000000000001
[  370.817988]  ffff8800ba8cb2e8 ffff8800ba8cb2d8 ffffffff81051afc ffff8800ba8cb2c8
[  370.817990]  ffffffffa00061a8 000000000000041e 0000000000000000 ffff8800ba8cba28
[  370.817993] Call Trace:
[  370.817999]  [<ffffffff819dd7af>] dump_stack+0x4f/0x7b
[  370.818002]  [<ffffffff81051afc>] warn_slowpath_common+0x8c/0xd0
[  370.818004]  [<ffffffff81051b86>] warn_slowpath_fmt+0x46/0x50
[  370.818006]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
[  370.818008]  [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90
[  370.818010]  [<ffffffff810776ef>] __might_sleep+0x7f/0x90
[  370.818014]  [<ffffffffa0000c03>] raid1_unplug+0xd3/0x170 [raid1]
[  370.818024]  [<ffffffff81421d9a>] blk_flush_plug_list+0x8a/0x1e0
[  370.818028]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
[  370.818031]  [<ffffffff819e21b0>] io_schedule_timeout+0x130/0x140
[  370.818033]  [<ffffffff819e3586>] bit_wait_io+0x36/0x50
[  370.818034]  [<ffffffff819e31b5>] __wait_on_bit+0x65/0x90
[  370.818041]  [<ffffffff8125b67c>] ? ext4_read_block_bitmap_nowait+0xbc/0x630
[  370.818043]  [<ffffffff819e3550>] ? bit_wait+0x50/0x50
[  370.818045]  [<ffffffff819e3302>] out_of_line_wait_on_bit+0x72/0x80
[  370.818047]  [<ffffffff810935e0>] ? autoremove_wake_function+0x40/0x40
[  370.818050]  [<ffffffff811de744>] __wait_on_buffer+0x44/0x50
[  370.818053]  [<ffffffff8125ae80>] ext4_wait_block_bitmap+0xe0/0xf0
[  370.818058]  [<ffffffff812975d6>] ext4_mb_init_cache+0x206/0x790
[  370.818062]  [<ffffffff8114bc6c>] ? lru_cache_add+0x1c/0x50
[  370.818064]  [<ffffffff81297c7e>] ext4_mb_init_group+0x11e/0x200
[  370.818066]  [<ffffffff81298231>] ext4_mb_load_buddy+0x341/0x360
[  370.818068]  [<ffffffff8129a1a3>] ext4_mb_find_by_goal+0x93/0x2f0
[  370.818070]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
[  370.818072]  [<ffffffff8129ab67>] ext4_mb_regular_allocator+0x67/0x460
[  370.818074]  [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0
[  370.818076]  [<ffffffff8129ca4b>] ext4_mb_new_blocks+0x4cb/0x620
[  370.818079]  [<ffffffff81290956>] ext4_ext_map_blocks+0x4c6/0x14d0
[  370.818081]  [<ffffffff812a4d4e>] ? ext4_es_lookup_extent+0x4e/0x290
[  370.818085]  [<ffffffff8126399d>] ext4_map_blocks+0x14d/0x4f0
[  370.818088]  [<ffffffff81266fbd>] ext4_writepages+0x76d/0xe50
[  370.818094]  [<ffffffff81149691>] do_writepages+0x21/0x50
[  370.818097]  [<ffffffff811d5c00>] __writeback_single_inode+0x60/0x490
[  370.818099]  [<ffffffff811d630a>] writeback_sb_inodes+0x2da/0x590
[  370.818103]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
[  370.818105]  [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50
[  370.818107]  [<ffffffff811d665f>] __writeback_inodes_wb+0x9f/0xd0
[  370.818109]  [<ffffffff811d69db>] wb_writeback+0x34b/0x3c0
[  370.818111]  [<ffffffff811d70df>] bdi_writeback_workfn+0x23f/0x550
[  370.818116]  [<ffffffff8106bbd8>] process_one_work+0x1c8/0x570
[  370.818117]  [<ffffffff8106bb5b>] ? process_one_work+0x14b/0x570
[  370.818119]  [<ffffffff8106c09b>] worker_thread+0x11b/0x470
[  370.818121]  [<ffffffff8106bf80>] ? process_one_work+0x570/0x570
[  370.818124]  [<ffffffff81071868>] kthread+0xf8/0x110
[  370.818126]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
[  370.818129]  [<ffffffff819e9322>] ret_from_fork+0x42/0x70
[  370.818131]  [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210
[  370.818132] ---[ end trace 7b4deb71e68b6605 ]---

V2: don't change ->in_iowait

Cc: NeilBrown <neilb@suse.de>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      5596d0d5
    • Shaohua Li's avatar
      blk: clean up plug · dd6cf3e1
      Shaohua Li authored 
      Current code looks like inner plug gets flushed with a
blk_finish_plug(). Actually it's a nop. All requests/callbacks are added
to current->plug, while only outmost plug is assigned to current->plug.
So inner plug always has empty request/callback list, which makes
blk_flush_plug_list() a nop. This tries to make the code more clear.
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Reviewed-by: default avatarJeff Moyer <jmoyer@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
      dd6cf3e1
  9. 05 May, 2015 12 commits
  11. 04 May, 2015 5 commits
    • Álvaro Fernández Rojas's avatar
      hwrng: bcm63xx - Fix driver compilation · f440c4ee
      Álvaro Fernández Rojas authored 
      - s/clk_didsable_unprepare/clk_disable_unprepare
- s/prov/priv
- s/error/ret (bcm63xx_rng_probe)

Fixes: 6229c160 ("hwrng: bcm63xx - make use of devm_hwrng_register")
Signed-off-by: default avatarÁlvaro Fernández Rojas <noltari@gmail.com>
Acked-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      f440c4ee
    • Daniel Borkmann's avatar
      lib: make memzero_explicit more robust against dead store elimination · 7829fb09
      Daniel Borkmann authored 
      In commit 0b053c95 ("lib: memzero_explicit: use barrier instead
of OPTIMIZER_HIDE_VAR"), we made memzero_explicit() more robust in
case LTO would decide to inline memzero_explicit() and eventually
find out it could be elimiated as dead store.

While using barrier() works well for the case of gcc, recent efforts
from LLVMLinux people suggest to use llvm as an alternative to gcc,
and there, Stephan found in a simple stand-alone user space example
that llvm could nevertheless optimize and thus elimitate the memset().
A similar issue has been observed in the referenced llvm bug report,
which is regarded as not-a-bug.

Based on some experiments, icc is a bit special on its own, while it
doesn't seem to eliminate the memset(), it could do so with an own
implementation, and then result in similar findings as with llvm.

The fix in this patch now works for all three compilers (also tested
with more aggressive optimization levels). Arguably, in the current
kernel tree it's more of a theoretical issue, but imho, it's better
to be pedantic about it.

It's clearly visible with gcc/llvm though, with the below code: if we
would have used barrier() only here, llvm would have omitted clearing,
not so with barrier_data() variant:

  static inline void memzero_explicit(void *s, size_t count)
  {
    memset(s, 0, count);
    barrier_data(s);
  }

  int main(void)
  {
    char buff[20];
    memzero_explicit(buff, sizeof(buff));
    return 0;
  }

  $ gcc -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x0000000000400400  <+0>: lea   -0x28(%rsp),%rax
   0x0000000000400405  <+5>: movq  $0x0,-0x28(%rsp)
   0x000000000040040e <+14>: movq  $0x0,-0x20(%rsp)
   0x0000000000400417 <+23>: movl  $0x0,-0x18(%rsp)
   0x000000000040041f <+31>: xor   %eax,%eax
   0x0000000000400421 <+33>: retq
  End of assembler dump.

  $ clang -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x00000000004004f0  <+0>: xorps  %xmm0,%xmm0
   0x00000000004004f3  <+3>: movaps %xmm0,-0x18(%rsp)
   0x00000000004004f8  <+8>: movl   $0x0,-0x8(%rsp)
   0x0000000000400500 <+16>: lea    -0x18(%rsp),%rax
   0x0000000000400505 <+21>: xor    %eax,%eax
   0x0000000000400507 <+23>: retq
  End of assembler dump.

As gcc, clang, but also icc defines __GNUC__, it's sufficient to define
this in compiler-gcc.h only to be picked up. For a fallback or otherwise
unsupported compiler, we define it as a barrier. Similarly, for ecc which
does not support gcc inline asm.

Reference: https://llvm.org/bugs/show_bug.cgi?id=15495Reported-by: default avatarStephan Mueller <smueller@chronox.de>
Tested-by: default avatarStephan Mueller <smueller@chronox.de>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: mancha security <mancha1@zoho.com>
Cc: Mark Charlebois <charlebm@gmail.com>
Cc: Behan Webster <behanw@converseincode.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      7829fb09
    • Linus Torvalds's avatar
      Linux 4.1-rc2 · 5ebe6afa
      Linus Torvalds authored
      5ebe6afa
    • Linus Torvalds's avatar
      Merge tag 'for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 · 8663da2c
      Linus Torvalds authored 
      Pull ext4 fixes from Ted Ts'o:
 "Some miscellaneous bug fixes and some final on-disk and ABI changes
  for ext4 encryption which provide better security and performance"

* tag 'for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix growing of tiny filesystems
  ext4: move check under lock scope to close a race.
  ext4: fix data corruption caused by unwritten and delayed extents
  ext4 crypto: remove duplicated encryption mode definitions
  ext4 crypto: do not select from EXT4_FS_ENCRYPTION
  ext4 crypto: add padding to filenames before encrypting
  ext4 crypto: simplify and speed up filename encryption
      8663da2c
    • Linus Torvalds's avatar
      Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux · 101a6fd3
      Linus Torvalds authored 
      Pull drm fixes from Dave Airlie:
 "One intel fix, one rockchip fix, and a bunch of radeon fixes for some
  regressions from audio rework and vm stability"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/i915/chv: Implement WaDisableShadowRegForCpd
  drm/radeon: fix userptr return value checking (v2)
  drm/radeon: check new address before removing old one
  drm/radeon: reset BOs address after clearing it.
  drm/radeon: fix lockup when BOs aren't part of the VM on release
  drm/radeon: add SI DPM quirk for Sapphire R9 270 Dual-X 2G GDDR5
  drm/radeon: adjust pll when audio is not enabled
  drm/radeon: only enable audio streams if the monitor supports it
  drm/radeon: only mark audio as connected if the monitor supports it (v3)
  drm/radeon/audio: don't enable packets until the end
  drm/radeon: drop dce6_dp_enable
  drm/radeon: fix ordering of AVI packet setup
  drm/radeon: Use drm_calloc_ab for CS relocs
  drm/rockchip: fix error check when getting irq
  MAINTAINERS: add entry for Rockchip drm drivers
      101a6fd3
  13. 03 May, 2015 5 commits
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