diff options
| author | Kent Overstreet <koverstreet@google.com> | 2013-05-07 16:18:39 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-07 18:38:28 -0700 |
| commit | 11599ebac4a249ab3c8b9a535c21db7a51458c0a (patch) | |
| tree | c5927106704034f4dbe6c10ae2c2c6bd60df42d8 /include | |
| parent | 1d98ebfccc15aeea87a7c48d50d7343e1ce8daae (diff) | |
aio: make aio_put_req() lockless
Freeing a kiocb needed to touch the kioctx for three things:
* Pull it off the reqs_active list
* Decrementing reqs_active
* Issuing a wakeup, if the kioctx was in the process of being freed.
This patch moves these to aio_complete(), for a couple reasons:
* aio_complete() already has to issue the wakeup, so if we drop the
kioctx refcount before aio_complete does its wakeup we don't have to
do it twice.
* aio_complete currently has to take the kioctx lock, so it makes sense
for it to pull the kiocb off the reqs_active list too.
* A later patch is going to change reqs_active to include unreaped
completions - this will mean allocating a kiocb doesn't have to look
at the ringbuffer. So taking the decrement of reqs_active out of
kiocb_free() is useful prep work for that patch.
This doesn't really affect cancellation, since existing (usb) code that
implements a cancel function still calls aio_complete() - we just have
to make sure that aio_complete does the necessary teardown for cancelled
kiocbs.
It does affect code paths where we free kiocbs that were never
submitted; they need to decrement reqs_active and pull the kiocb off the
reqs_active list. This occurs in two places: kiocb_batch_free(), which
is going away in a later patch, and the error path in io_submit_one.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/aio.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/aio.h b/include/linux/aio.h index 7b1eb234e0a..1e728f0086f 100644 --- a/include/linux/aio.h +++ b/include/linux/aio.h @@ -49,7 +49,7 @@ struct kioctx; */ struct kiocb { unsigned long ki_flags; - int ki_users; + atomic_t ki_users; unsigned ki_key; /* id of this request */ struct file *ki_filp; @@ -96,7 +96,7 @@ static inline bool is_sync_kiocb(struct kiocb *kiocb) static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp) { *kiocb = (struct kiocb) { - .ki_users = 1, + .ki_users = ATOMIC_INIT(1), .ki_key = KIOCB_SYNC_KEY, .ki_filp = filp, .ki_obj.tsk = current, |