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Commit fb775faa authored by Stefan Bühler's avatar Stefan Bühler Committed by Jens Axboe
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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: default avatarStefan Bühler <source@stbuehler.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0d7bae69

fs/io_uring.c

+2 −1
Original line number Diff line number Diff line
@@ -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;