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UPSTREAM: eventpoll: add EPOLL_URING_WAKE poll wakeup flag

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[ Upstream commit caf1aeaffc ]

We can have dependencies between epoll and io_uring. Consider an epoll
context, identified by the epfd file descriptor, and an io_uring file
descriptor identified by iofd. If we add iofd to the epfd context, and
arm a multishot poll request for epfd with iofd, then the multishot
poll request will repeatedly trigger and generate events until terminated
by CQ ring overflow. This isn't a desired behavior.

Add EPOLL_URING so that io_uring can pass it in as part of the poll wakeup
key, and io_uring can check for that to detect a potential recursive
invocation.

Cc: stable@vger.kernel.org # 6.0
Change-Id: Ifafcb236b2cfe3ca3e7254a0155625fce00fd038
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 2f09377502)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Jens Axboe
2022-11-20 10:10:53 -07:00
committed by Greg Kroah-Hartman
parent 7c9f38c09b
commit d7a47b29d5
2 changed files with 16 additions and 8 deletions
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6
include/uapi/linux/eventpoll.h
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@@ -41,6 +41,12 @@
#define EPOLLMSG (__force __poll_t)0x00000400
#define EPOLLRDHUP (__force __poll_t)0x00002000
/*
* Internal flag - wakeup generated by io_uring, used to detect recursion back
* into the io_uring poll handler.
*/
#define EPOLL_URING_WAKE ((__force __poll_t)(1U << 27))
/* Set exclusive wakeup mode for the target file descriptor */
#define EPOLLEXCLUSIVE ((__force __poll_t)(1U << 28))