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authorStefan Bühler2019-04-19 11:57:46 +0200
committerJens Axboe2019-04-22 11:00:58 -0600
commitfb775faa9e46ff481e4ced11116c9bd45359cb43 (patch)
tree324047efa74cb0da1583ddc4cafb79bbb6d7356e
parent0d7bae69c574c5f25802f8a71252e7d66933a3ab (diff)
io_uring: fix poll full SQ detection
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 <source@stbuehler.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/io_uring.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 69910fd9ccca..b998e98acd01 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;