From af1b64906143883e4ed9620c3414a5f18adce473 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Stefan=20B=C3=BChler?= Date: Fri, 19 Apr 2019 11:57:46 +0200 Subject: [PATCH 0461/2944] io_uring: fix poll full SQ detection MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 0d7bae69c574c5f25802f8a71252e7d66933a3ab upstream. io_uring_poll shouldn't signal EPOLLOUT | EPOLLWRNORM if the queue is full; the old check would always signal EPOLLOUT | EPOLLWRNORM (unless there were U32_MAX - 1 entries in the SQ queue). Signed-off-by: Stefan Bühler Signed-off-by: Jens Axboe Signed-off-by: Joseph Qi Reviewed-by: Jeffle Xu Acked-by: Caspar Zhang --- fs/io_uring.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 4979aad..1706b71 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2576,7 +2576,8 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait) poll_wait(file, &ctx->cq_wait, wait); /* See comment at the top of this file */ smp_rmb(); - if (READ_ONCE(ctx->sq_ring->r.tail) + 1 != ctx->cached_sq_head) + if (READ_ONCE(ctx->sq_ring->r.tail) - ctx->cached_sq_head != + ctx->sq_ring->ring_entries) mask |= EPOLLOUT | EPOLLWRNORM; if (READ_ONCE(ctx->cq_ring->r.head) != ctx->cached_cq_tail) mask |= EPOLLIN | EPOLLRDNORM; -- 1.8.3.1