Jens Axboe 4ef66581d7 eventfd: provide a eventfd_signal_mask() helper
[ Upstream commit 03e02acda8e267a8183e1e0ed289ff1ef9cd7ed8 ]

This is identical to eventfd_signal(), but it allows the caller to pass
in a mask to be used for the poll wakeup key. The use case is avoiding
repeated multishot triggers if we have a dependency between eventfd and
io_uring.

If we setup an eventfd context and register that as the io_uring eventfd,
and at the same time queue a multishot poll request for the eventfd
context, then any CQE posted will repeatedly trigger the multishot request
until it terminates when the CQ ring overflows.

In preparation for io_uring detecting this circular dependency, add the
mentioned helper so that io_uring can pass in EPOLL_URING as part of the
poll wakeup key.

Cc: stable@vger.kernel.org # 6.0
[axboe: fold in !CONFIG_EVENTFD fix from Zhang Qilong]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-04 11:39:24 +01:00
..
2020-10-16 11:11:22 -07:00
2021-09-18 13:40:15 +02:00
2022-11-25 17:45:56 +01:00
2020-09-10 14:03:31 -07:00
2022-06-09 10:21:16 +02:00
2023-01-04 11:39:23 +01:00