Commit a1f58ba4 authored Oct 23, 2019 by zhangyi (F) Committed by Jens Axboe Oct 23, 2019

io_uring: correct timeout req sequence when inserting a new entry



The sequence number of the timeout req (req->sequence) indicate the
expected completion request. Because of each timeout req consume a
sequence number, so the sequence of each timeout req on the timeout
list shouldn't be the same. But now, we may get the same number (also
incorrect) if we insert a new entry before the last one, such as submit
such two timeout reqs on a new ring instance below.

                    req->sequence
 req_1 (count = 2):       2
 req_2 (count = 1):       2

Then, if we submit a nop req, req_2 will still timeout even the nop req
finished. This patch fix this problem by adjust the sequence number of
each reordered reqs when inserting a new entry.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent ef03681a

fs/io_uring.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -1912,6 +1912,7 @@ static int io_timeout(struct io_kiocb req, const struct io_uring_sqe sqe)
		struct io_ring_ctx *ctx = req->ctx;
		struct list_head *entry;
		struct timespec64 ts;
		unsigned span = 0;

		if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
		return -EINVAL;
		@@ -1960,9 +1961,17 @@ static int io_timeout(struct io_kiocb req, const struct io_uring_sqe sqe)
		if (ctx->cached_sq_head < nxt_sq_head)
		tmp += UINT_MAX;

		if (tmp >= tmp_nxt)
		if (tmp > tmp_nxt)
		break;

		/*
		* Sequence of reqs after the insert one and itself should
		* be adjusted because each timeout req consumes a slot.
		*/
		span++;
		nxt->sequence++;
		}
		req->sequence -= span;
		list_add(&req->list, entry);
		spin_unlock_irq(&ctx->completion_lock);

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