linux-stable.git/fs/jffs2, branch linux-3.3.y

jffs2: Fix lock acquisition order bug in gc path

2012-05-21T17:46:20+00:00

commit 226bb7df3d22bcf4a1c0fe8206c80cc427498eae upstream.

The locking policy is such that the erase_complete_block spinlock is
nested within the alloc_sem mutex.  This fixes a case in which the
acquisition order was erroneously reversed.  This issue was caught by
the following lockdep splat:

   =======================================================
   [ INFO: possible circular locking dependency detected ]
   3.0.5 #1
   -------------------------------------------------------
   jffs2_gcd_mtd6/299 is trying to acquire lock:
    (&c->alloc_sem){+.+.+.}, at: [] jffs2_garbage_collect_pass+0x314/0x890

   but task is already holding lock:
    (&(&c->erase_completion_lock)->rlock){+.+...}, at: [] jffs2_garbage_collect_pass+0x308/0x890

   which lock already depends on the new lock.

   the existing dependency chain (in reverse order) is:

   -> #1 (&(&c->erase_completion_lock)->rlock){+.+...}:
          [] validate_chain+0xe6c/0x10bc
          [] __lock_acquire+0x54c/0xba4
          [] lock_acquire+0xa4/0x114
          [] _raw_spin_lock+0x3c/0x4c
          [] jffs2_garbage_collect_pass+0x4c/0x890
          [] jffs2_garbage_collect_thread+0x1b4/0x1cc
          [] kthread+0x98/0xa0
          [] kernel_thread_exit+0x0/0x8

   -> #0 (&c->alloc_sem){+.+.+.}:
          [] print_circular_bug+0x70/0x2c4
          [] validate_chain+0x1034/0x10bc
          [] __lock_acquire+0x54c/0xba4
          [] lock_acquire+0xa4/0x114
          [] mutex_lock_nested+0x74/0x33c
          [] jffs2_garbage_collect_pass+0x314/0x890
          [] jffs2_garbage_collect_thread+0x1b4/0x1cc
          [] kthread+0x98/0xa0
          [] kernel_thread_exit+0x0/0x8

   other info that might help us debug this:

    Possible unsafe locking scenario:

          CPU0                    CPU1
          ----                    ----
     lock(&(&c->erase_completion_lock)->rlock);
                                  lock(&c->alloc_sem);
                                  lock(&(&c->erase_completion_lock)->rlock);
     lock(&c->alloc_sem);

    *** DEADLOCK ***

   1 lock held by jffs2_gcd_mtd6/299:
    #0:  (&(&c->erase_completion_lock)->rlock){+.+...}, at: [] jffs2_garbage_collect_pass+0x308/0x890

   stack backtrace:
   [] (unwind_backtrace+0x0/0x100) from [] (dump_stack+0x20/0x24)
   [] (dump_stack+0x20/0x24) from [] (print_circular_bug+0x1c8/0x2c4)
   [] (print_circular_bug+0x1c8/0x2c4) from [] (validate_chain+0x1034/0x10bc)
   [] (validate_chain+0x1034/0x10bc) from [] (__lock_acquire+0x54c/0xba4)
   [] (__lock_acquire+0x54c/0xba4) from [] (lock_acquire+0xa4/0x114)
   [] (lock_acquire+0xa4/0x114) from [] (mutex_lock_nested+0x74/0x33c)
   [] (mutex_lock_nested+0x74/0x33c) from [] (jffs2_garbage_collect_pass+0x314/0x890)
   [] (jffs2_garbage_collect_pass+0x314/0x890) from [] (jffs2_garbage_collect_thread+0x1b4/0x1cc)
   [] (jffs2_garbage_collect_thread+0x1b4/0x1cc) from [] (kthread+0x98/0xa0)
   [] (kthread+0x98/0xa0) from [] (kernel_thread_exit+0x0/0x8)

This was introduce in '81cfc9f jffs2: Fix serious write stall due to erase'.

Signed-off-by: Josh Cartwright 
Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse 
Signed-off-by: Greg Kroah-Hartman

jffs2: do not initialize variable unnecessarily

2012-01-11T09:53:51+00:00

Remove unnecessary initializer for a local variable.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

Merge tag 'for-linus-3.3' of git://git.infradead.org/mtd-2.6

2012-01-10T21:45:22+00:00

MTD pull for 3.3

* tag 'for-linus-3.3' of git://git.infradead.org/mtd-2.6: (113 commits)
  mtd: Fix dependency for MTD_DOC200x
  mtd: do not use mtd->block_markbad directly
  logfs: do not use 'mtd->block_isbad' directly
  mtd: introduce mtd_can_have_bb helper
  mtd: do not use mtd->suspend and mtd->resume directly
  mtd: do not use mtd->lock, unlock and is_locked directly
  mtd: do not use mtd->sync directly
  mtd: harmonize mtd_writev usage
  mtd: do not use mtd->lock_user_prot_reg directly
  mtd: mtd->write_user_prot_reg directly
  mtd: do not use mtd->read_*_prot_reg directly
  mtd: do not use mtd->get_*_prot_info directly
  mtd: do not use mtd->read_oob directly
  mtd: mtdoops: do not use mtd->panic_write directly
  romfs: do not use mtd->get_unmapped_area directly
  mtd: do not use mtd->get_unmapped_area directly
  mtd: do use mtd->point directly
  mtd: introduce mtd_has_oob helper
  mtd: mtdcore: export symbols cleanup
  mtd: clean-up the default_mtd_writev function
  ...

Fix up trivial edit/remove conflict in drivers/staging/spectra/lld_mtd.c

mtd: do not use mtd->block_markbad directly

2012-01-09T18:26:26+00:00

Instead, use the new 'mtd_can_have_bb()', or just rely on 'mtd_block_markbad()'
return code, which will be -EOPNOTSUPP if bad blocks are not supported.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: do not use mtd->sync directly

2012-01-09T18:26:21+00:00

This patch teaches 'mtd_sync()' to do nothing when the MTD driver does
not have the '->sync()' method, which allows us to remove all direct
'mtd->sync' accesses.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: harmonize mtd_writev usage

2012-01-09T18:26:19+00:00

This patch makes the 'mtd_writev()' function more usable and logical. We first
teach it to fall-back to the 'default_mtd_writev()' function if the MTD driver
does not define its own '->writev()' method. Then we make block2mtd and JFFS2
just 'mtd_writev()' instead of 'default_mtd_writev()' function. This means we
can now stop exporting 'default_mtd_writev()' and instead, export
'mtd_writev()'. This is much cleaner and more logical, as well as allows us to
get read of another direct 'mtd->writev' access in JFFS2.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: do use mtd->point directly

2012-01-09T18:26:09+00:00

Remove direct usage of the "mtd->point" function pointer. Instead,
test the mtd_point() return code for '-EOPNOTSUPP'.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

jffs: remove custom mtd_fake_writev function

2012-01-09T18:26:04+00:00

Instead, use 'default_mtd_writev()' function which MTD provides.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: introduce mtd_block_markbad interface

2012-01-09T18:25:48+00:00

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: introduce mtd_block_isbad interface

2012-01-09T18:25:47+00:00

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse