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authorPavel Begunkov <asml.silence@gmail.com>2021-09-08 20:49:17 +0100
committerJens Axboe <axboe@kernel.dk>2021-09-08 13:57:56 -0600
commitc57a91fb1ccfa203ba3e31e5a389cb04de5b0561 (patch)
treed03ab06beb7d97625301c48c80df6b3d9fef5489
parent713b9825a4c47897f66ad69409581e7734a8728e (diff)
io_uring: fix missing mb() before waitqueue_active
In case of !SQPOLL, io_cqring_ev_posted_iopoll() doesn't provide a memory barrier required by waitqueue_active(&ctx->poll_wait). There is a wq_has_sleeper(), which does smb_mb() inside, but it's called only for SQPOLL. Fixes: 5fd4617840596 ("io_uring: be smarter about waking multiple CQ ring waiters") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/2982e53bcea2274006ed435ee2a77197107d8a29.1631130542.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index d816c09c88a5..d80d8359501f 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1619,8 +1619,11 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
{
+ /* see waitqueue_active() comment */
+ smp_mb();
+
if (ctx->flags & IORING_SETUP_SQPOLL) {
- if (wq_has_sleeper(&ctx->cq_wait))
+ if (waitqueue_active(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
}
if (io_should_trigger_evfd(ctx))