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authorPavel Begunkov <asml.silence@gmail.com>2021-01-07 06:15:43 +0300
committerJens Axboe <axboe@kernel.dk>2021-01-07 17:48:09 +0300
commitb1445e59cc9a10fdb8f83810ae1f4feb941ab36b (patch)
tree3f7ec8dc6d43cbc0baf2b2d33824ba266e0aea0d /fs
parent4aa84f2ffa81f71e15e5cffc2cc6090dbee78f8e (diff)
downloadlinux-b1445e59cc9a10fdb8f83810ae1f4feb941ab36b.tar.xz
io_uring: synchronise ev_posted() with waitqueues
waitqueue_active() needs smp_mb() to be in sync with waitqueues modification, but we miss it in io_cqring_ev_posted*() apart from cq_wait() case. Take an smb_mb() out of wq_has_sleeper() making it waitqueue_active(), and place it a few lines before, so it can synchronise other waitqueue_active() as well. The patch doesn't add any additional overhead, so even if there are no problems currently, it's just safer to have it this way. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 401316fe2ae2..cb57e0360fcb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1700,13 +1700,16 @@ static inline unsigned __io_cqring_events(struct io_ring_ctx *ctx)
static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
{
+ /* see waitqueue_active() comment */
+ smp_mb();
+
if (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
if (ctx->sq_data && waitqueue_active(&ctx->sq_data->wait))
wake_up(&ctx->sq_data->wait);
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
- if (wq_has_sleeper(&ctx->cq_wait)) {
+ if (waitqueue_active(&ctx->cq_wait)) {
wake_up_interruptible(&ctx->cq_wait);
kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
}
@@ -1714,13 +1717,16 @@ 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 (waitqueue_active(&ctx->wait))
wake_up(&ctx->wait);
}
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
- if (wq_has_sleeper(&ctx->cq_wait)) {
+ if (waitqueue_active(&ctx->cq_wait)) {
wake_up_interruptible(&ctx->cq_wait);
kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
}