From dbd0f6d6c2a11eb9c31ca9cd454f95bb5713e92e Mon Sep 17 00:00:00 2001 From: Zhengyuan Liu Date: Sat, 13 Jul 2019 11:58:26 +0800 Subject: io_uring: fix the sequence comparison in io_sequence_defer sq->cached_sq_head and cq->cached_cq_tail are both unsigned int. If cached_sq_head overflows before cached_cq_tail, then we may miss a barrier req. As cached_cq_tail always follows cached_sq_head, the NQ should be enough. Cc: stable@vger.kernel.org Fixes: de0617e46717 ("io_uring: add support for marking commands as draining") Signed-off-by: Zhengyuan Liu Signed-off-by: Jens Axboe --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index d682049c07b2..708d133492a1 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -429,7 +429,7 @@ static inline bool io_sequence_defer(struct io_ring_ctx *ctx, if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN) return false; - return req->sequence > ctx->cached_cq_tail + ctx->sq_ring->dropped; + return req->sequence != ctx->cached_cq_tail + ctx->sq_ring->dropped; } static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx) -- cgit v1.2.3-59-g8ed1b