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| author | Pavel Begunkov <asml.silence@gmail.com> | 2021-01-07 04:15:43 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-01-07 15:48:09 +0100 |
| commit | b1445e59cc9a10fdb8f83810ae1f4feb941ab36b (patch) | |
| tree | 3f7ec8dc6d43cbc0baf2b2d33824ba266e0aea0d | |
| parent | io_uring: dont kill fasync under completion_lock (diff) | |
| download | linux-b1445e59cc9a10fdb8f83810ae1f4feb941ab36b.tar.xz linux-b1445e59cc9a10fdb8f83810ae1f4feb941ab36b.zip | |
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>
| -rw-r--r-- | fs/io_uring.c | 10 |
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); } |