linux-toradex.git/fs/aio.c, branch v2.6.16.44-rc1

[PATCH] rcu file: use atomic primitives

2006-01-09T04:13:48+00:00

Use atomic_inc_not_zero for rcu files instead of special case rcuref.

Signed-off-by: Nick Piggin 
Cc: "Paul E. McKenney" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: replace locking comments with assert_spin_locked()

2005-11-14T02:14:16+00:00

aio: replace locking comments with assert_spin_locked()

Signed-off-by: Zach Brown 
Acked-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: remove kioctx from mm_struct

2005-11-14T02:14:16+00:00

Sync iocbs have a life cycle that don't need a kioctx.  Their retrying, if
any, is done in the context of their owner who has allocated them on the
stack.

The sole user of a sync iocb's ctx reference was aio_complete() checking for
an elevated iocb ref count that could never happen.  No path which grabs an
iocb ref has access to sync iocbs.

If we were to implement sync iocb cancelation it would be done by the owner of
the iocb using its on-stack reference.

Removing this chunk from aio_complete allows us to remove the entire kioctx
instance from mm_struct, reducing its size by a third.  On a i386 testing box
the slab size went from 768 to 504 bytes and from 5 to 8 per page.

Signed-off-by: Zach Brown 
Acked-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: remove aio_max_nr accounting race

2005-11-07T15:53:38+00:00

AIO was adding a new context's max requests to the global total before
testing if that resulting total was over the global limit.  This let
innocent tasks get their new limit tested along with a racing guilty task
that was crossing the limit.  This serializes the _nr accounting with a
spinlock It also switches to using unsigned long for the global totals.
Individual contexts are still limited to an unsigned int's worth of
requests by the syscall interface.

The problem and fix were verified with a simple program that spun creating
and destroying a context while holding on to another long lived context.
Before the patch a task creating a tiny context could get a spurious EAGAIN
if it raced with a task creating a very large context that overran the
limit.

Signed-off-by: Zach Brown 
Cc: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio syscalls are not checked by lsm

2005-10-23T23:38:38+00:00

Another case of missing call to security_file_permission: aio functions
(namely, io_submit) does not check credentials with security modules.

Below is the simple patch to the problem.  It seems that it is enough to
check for rights at the request submission time.

Signed-off-by: Kostik Belousov 
Signed-off-by: Chris Wright 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: revert lock_kiocb()

2005-10-18T00:03:57+00:00

lock_kiocb() was introduced to serialize retrying and cancellation.  In the
process of doing so it tried to sleep waiting for KIF_LOCKED while holding
the ctx_lock spinlock.  Recent fixes have ensured that multiple concurrent
retries won't be attempted for a given iocb.  Cancel has other problems and
has no significant in-tree users that have been complaining about it.  So
for the immediate future we'll revert sleeping with the lock held and will
address proper cancellation and retry serialization in the future.

Signed-off-by: Zach Brown 
Acked-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: avoid extra aio_{read,write} call when ki_left == 0

2005-09-30T19:41:17+00:00

Recently aio_p{read,write} changed to perform retries internally rather
than returning -EIOCBRETRY.  This inadvertantly resulted in always calling
aio_{read,write} with ki_left at 0 which would in turn immediately return
0.  Harmless, but we can avoid this call by checking in the caller.

Signed-off-by: Zach Brown 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: remove unlocked task_list test and resulting race

2005-09-30T19:41:17+00:00

Only one of the run or kick path is supposed to put an iocb on the run
list.  If both of them do it than one of them can end up referencing a
freed iocb.  The kick path could delete the task_list item from the wait
queue before getting the ctx_lock and putting the iocb on the run list.
The run path was testing the task_list item outside the lock so that it
could catch ki_retry methods that return -EIOCBRETRY *without* putting the
iocb on a wait queue and promising to call kick_iocb.  This unlocked check
could then race with the kick path to cause both to try and put the iocb on
the run list.

The patch stops the run path from testing task_list by requring that any
ki_retry that returns -EIOCBRETRY *must* guarantee that kick_iocb() will be
called in the future.  aio_p{read,write}, the only in-tree -EIOCBRETRY
users, are updated.

Signed-off-by: Zach Brown 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] aio: lock around kiocbTryKick()

2005-09-30T19:41:17+00:00

Only one of the run or kick path is supposed to put an iocb on the run
list.  If both of them do it than one of them can end up referencing a
freed iocb.  The kick patch could set the Kicked bit before acquiring the
ctx_lock and putting the iocb on the run list.  The run path, while holding
the ctx_lock, could see this partial kick and mistake it for a kick that
was deferred while it was doing work with the run_list NULLed out.  It
would then race with the kick thread to add the iocb to the run list.

This patch moves the kick setting under the ctx_lock so that only one of
the kick or run path queues the iocb on the run list, as intended.

Signed-off-by: Zach Brown 
Signed-off-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Add smp_mb__after_clear_bit() to unlock_kiocb()

2005-09-17T18:50:02+00:00

Add smp_mb__after_clear_bit() to unlock_kiocb()

AIO's use of wait_on_bit_lock()/wake_up_bit() forgot to add a barrier
between clearing its lock bit and calling wake_up_bit() so wake_up_bit()'s
unlocked waitqueue_active() can race.  This puts AIO's use in line with the
others and the comment above wake_up_bit().

Signed-off-by: Zach Brown 
Acked-by: Benjamin LaHaise 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds