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io_uring: pass in EPOLL_URING_WAKE for eventfd signaling and wakeups

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[ Upstream commit 4464853277d0ccdb9914608dd1332f0fa2f9846f ]

Pass in EPOLL_URING_WAKE when signaling eventfd or doing poll related
wakups, so that we can check for a circular event dependency between
eventfd and epoll. If this flag is set when our wakeup handlers are
called, then we know we have a dependency that needs to terminate
multishot requests.

eventfd and epoll are the only such possible dependencies.

Cc: stable@vger.kernel.org # 6.0
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe 2022-12-23 07:04:49 -07:00 committed by Greg Kroah-Hartman
parent 4ef66581d7
commit 189556b05e
1 changed files with 20 additions and 7 deletions
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27
io_uring/io_uring.c
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@ -1626,13 +1626,15 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
* wake as many waiters as we need to.
*/
if (wq_has_sleeper(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
if (ctx->sq_data && waitqueue_active(&ctx->sq_data->wait))
wake_up(&ctx->sq_data->wait);
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
eventfd_signal_mask(ctx->cq_ev_fd, 1, EPOLL_URING_WAKE);
if (waitqueue_active(&ctx->poll_wait))
wake_up_interruptible(&ctx->poll_wait);
__wake_up(&ctx->poll_wait, TASK_INTERRUPTIBLE, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
}
static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
@ -1642,12 +1644,14 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
if (ctx->flags & IORING_SETUP_SQPOLL) {
if (waitqueue_active(&ctx->cq_wait))
wake_up_all(&ctx->cq_wait);
__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
}
if (io_should_trigger_evfd(ctx))
eventfd_signal(ctx->cq_ev_fd, 1);
eventfd_signal_mask(ctx->cq_ev_fd, 1, EPOLL_URING_WAKE);
if (waitqueue_active(&ctx->poll_wait))
wake_up_interruptible(&ctx->poll_wait);
__wake_up(&ctx->poll_wait, TASK_INTERRUPTIBLE, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
}
/* Returns true if there are no backlogged entries after the flush */
@ -5477,8 +5481,17 @@ static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
if (mask && !(mask & poll->events))
return 0;
if (io_poll_get_ownership(req))
if (io_poll_get_ownership(req)) {
/*
* If we trigger a multishot poll off our own wakeup path,
* disable multishot as there is a circular dependency between
* CQ posting and triggering the event.
*/
if (mask & EPOLL_URING_WAKE)
poll->events |= EPOLLONESHOT;
__io_poll_execute(req, mask);
}
return 1;
}