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io_uring: fix link lookup racing with link timeout

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We can't just go over linked requests because it may race with linked
timeouts. Take ctx->completion_lock in that case.

Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-11-05 22:31:37 +00:00 committed by Jens Axboe
parent 6b47ab81c9
commit 9a472ef7a3
1 changed files with 15 additions and 1 deletions
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16
fs/io_uring.c
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@ -8470,7 +8470,21 @@ static bool io_timeout_remove_link(struct io_ring_ctx *ctx,
static bool io_cancel_link_cb(struct io_wq_work *work, void *data)
{
return io_match_link(container_of(work, struct io_kiocb, work), data);
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
bool ret;
if (req->flags & REQ_F_LINK_TIMEOUT) {
unsigned long flags;
struct io_ring_ctx *ctx = req->ctx;
/* protect against races with linked timeouts */
spin_lock_irqsave(&ctx->completion_lock, flags);
ret = io_match_link(req, data);
spin_unlock_irqrestore(&ctx->completion_lock, flags);
} else {
ret = io_match_link(req, data);
}
return ret;
}
static void io_attempt_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)