| From | Kent Overstreet <> | Subject | [PATCH 33/33] aio: fix kioctx not being freed after cancellation at exit time | Date | Thu, 21 Mar 2013 09:35:54 -0700 |
| |
From: Benjamin LaHaise <bcrl@kvack.org>
The recent changes overhauling fs/aio.c introduced a bug that results in the kioctx not being freed when outstanding kiocbs are cancelled at exit_aio() time. Specifically, a kiocb that is cancelled has its completion events discarded by batch_complete_aio(), which then fails to wake up the process stuck in free_ioctx(). Fix this by removing the event suppression in batch_complete_aio() and modify the wait_event() condition in free_ioctx() appropriately.
This patch was tested with the cancel operation in the thread based code posted yesterday.
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org> Cc: Kent Overstreet <koverstreet@google.com> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Zach Brown <zab@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Kent Overstreet <koverstreet@google.com> --- fs/aio.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c index 4dbd240..d2c1a82 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -349,7 +349,9 @@ static void free_ioctx(struct kioctx *ctx) kunmap_atomic(ring); while (atomic_read(&ctx->reqs_available) < ctx->nr_events - 1) { - wait_event(ctx->wait, head != ctx->shadow_tail); + wait_event(ctx->wait, + (head != ctx->shadow_tail) || + (atomic_read(&ctx->reqs_available) >= ctx->nr_events - 1)); avail = (head <= ctx->shadow_tail ? ctx->shadow_tail : ctx->nr_events) - head; @@ -774,17 +776,6 @@ void batch_complete_aio(struct batch_complete *batch) n = rb_parent(n); } - if (unlikely(xchg(&req->ki_cancel, - KIOCB_CANCELLED) == KIOCB_CANCELLED)) { - /* - * Can't use the percpu reqs_available here - could race - * with free_ioctx() - */ - atomic_inc(&req->ki_ctx->reqs_available); - aio_put_req(req); - continue; - } - if (unlikely(req->ki_eventfd != eventfd)) { if (eventfd) { /* Make event visible */ -- 1.8.1.3
|