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    Subject[PATCH 5.18 109/181] io_uring: fix req->apoll_events
    Date
    From: Pavel Begunkov <asml.silence@gmail.com>

    [ Upstream commit aacf2f9f382c91df73f33317e28a4c34c8038986 ]

    apoll_events should be set once in the beginning of poll arming just as
    poll->events and not change after. However, currently io_uring resets it
    on each __io_poll_execute() for no clear reason. There is also a place
    in __io_arm_poll_handler() where we add EPOLLONESHOT to downgrade a
    multishot, but forget to do the same thing with ->apoll_events, which is
    buggy.

    Fixes: 81459350d581e ("io_uring: cache req->apoll->events in req->cflags")
    Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
    Reviewed-by: Hao Xu <howeyxu@tencent.com>
    Link: https://lore.kernel.org/r/0aef40399ba75b1a4d2c2e85e6e8fd93c02fc6e4.1655814213.git.asml.silence@gmail.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/io_uring.c | 12 ++++++++----
    1 file changed, 8 insertions(+), 4 deletions(-)

    diff --git a/fs/io_uring.c b/fs/io_uring.c
    index 1070d22a1c2b..38ecea726254 100644
    --- a/fs/io_uring.c
    +++ b/fs/io_uring.c
    @@ -5984,7 +5984,8 @@ static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
    io_req_complete_failed(req, ret);
    }

    -static void __io_poll_execute(struct io_kiocb *req, int mask, __poll_t events)
    +static void __io_poll_execute(struct io_kiocb *req, int mask,
    + __poll_t __maybe_unused events)
    {
    req->result = mask;
    /*
    @@ -5993,7 +5994,6 @@ static void __io_poll_execute(struct io_kiocb *req, int mask, __poll_t events)
    * CPU. We want to avoid pulling in req->apoll->events for that
    * case.
    */
    - req->apoll_events = events;
    if (req->opcode == IORING_OP_POLL_ADD)
    req->io_task_work.func = io_poll_task_func;
    else
    @@ -6143,6 +6143,8 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
    io_init_poll_iocb(poll, mask, io_poll_wake);
    poll->file = req->file;

    + req->apoll_events = poll->events;
    +
    ipt->pt._key = mask;
    ipt->req = req;
    ipt->error = 0;
    @@ -6173,8 +6175,10 @@ static int __io_arm_poll_handler(struct io_kiocb *req,

    if (mask) {
    /* can't multishot if failed, just queue the event we've got */
    - if (unlikely(ipt->error || !ipt->nr_entries))
    + if (unlikely(ipt->error || !ipt->nr_entries)) {
    poll->events |= EPOLLONESHOT;
    + req->apoll_events |= EPOLLONESHOT;
    + }
    __io_poll_execute(req, mask, poll->events);
    return 0;
    }
    @@ -6387,7 +6391,7 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
    return -EINVAL;

    io_req_set_refcount(req);
    - req->apoll_events = poll->events = io_poll_parse_events(sqe, flags);
    + poll->events = io_poll_parse_events(sqe, flags);
    return 0;
    }

    --
    2.35.1


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