diff options
| author | Stefan Bühler <source@stbuehler.de> | 2019-04-24 23:54:17 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-04-30 09:40:02 -0600 |
| commit | 4f7067c3fb7f2974363a28c597a41949d971af02 (patch) | |
| tree | 354d44d8bbdb9dd7e73596603932bfdcf797c686 /fs/io_uring.c | |
| parent | 1e84b97b7377bd0198f87b49ad3e396e84bf0458 (diff) | |
| download | lwn-4f7067c3fb7f2974363a28c597a41949d971af02.tar.gz lwn-4f7067c3fb7f2974363a28c597a41949d971af02.zip | |
io_uring: remove unnecessary barrier before wq_has_sleeper
wq_has_sleeper has a full barrier internally. The smp_rmb barrier in
io_uring_poll synchronizes with it.
Signed-off-by: Stefan Bühler <source@stbuehler.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 7ab93e854eb2..bb71b7f00bb3 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -418,12 +418,6 @@ static void io_commit_cqring(struct io_ring_ctx *ctx) /* order cqe stores with ring update */ smp_store_release(&ring->r.tail, ctx->cached_cq_tail); - /* - * Write sider barrier of tail update, app has read side. See - * comment at the top of this file. - */ - smp_wmb(); - if (wq_has_sleeper(&ctx->cq_wait)) { wake_up_interruptible(&ctx->cq_wait); kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN); @@ -2677,7 +2671,10 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait) __poll_t mask = 0; poll_wait(file, &ctx->cq_wait, wait); - /* See comment at the top of this file */ + /* + * synchronizes with barrier from wq_has_sleeper call in + * io_commit_cqring + */ smp_rmb(); if (READ_ONCE(ctx->sq_ring->r.tail) - ctx->cached_sq_head != ctx->sq_ring->ring_entries) |