From: Zhengyuan Liu liuzhengyuan@kylinos.cn
commit dbd0f6d6c2a11eb9c31ca9cd454f95bb5713e92e upstream.
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 liuzhengyuan@kylinos.cn Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -425,7 +425,7 @@ static inline bool io_sequence_defer(str 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)