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io_uring: don't delay iopoll'ed req completion

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->iopoll() may have completed current request, but instead of reaping
it, io_do_iopoll() just continues with the next request in the list.
As a result it can leave just polled and completed request in the list
up until next syscall. Even outer loop in io_iopoll_getevents() doesn't
help the situation.

E.g. poll_list: req0 -> req1
If req0->iopoll() completed both requests, and @min<=1,
then @req0 will be left behind.

Check whether a req was completed after ->iopoll().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-07-06 17:59:29 +03:00 committed by Jens Axboe
parent 8b3656af2a
commit 3aadc23e60
1 changed files with 4 additions and 0 deletions
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4
fs/io_uring.c
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@ -2015,6 +2015,10 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
if (ret < 0)
break;
/* iopoll may have completed current req */
if (READ_ONCE(req->iopoll_completed))
list_move_tail(&req->list, &done);
if (ret && spin)
spin = false;
ret = 0;