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authorKent Overstreet <koverstreet@google.com>2013-05-07 16:18:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-07 18:38:28 -0700
commit11599ebac4a249ab3c8b9a535c21db7a51458c0a (patch)
treec5927106704034f4dbe6c10ae2c2c6bd60df42d8 /include/linux
parent1d98ebfccc15aeea87a7c48d50d7343e1ce8daae (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/linux')
-rw-r--r--include/linux/aio.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/aio.h b/include/linux/aio.h
index 7b1eb234e0ab..1e728f0086f8 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,