Commit 83a4f865 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring/eventfd: abstract out ev_fd grab + release helpers 

In preparation for needing the ev_fd grabbing (and releasing) from
another path, abstract out two helpers for that.

Link: https://lore.kernel.org/r/20240921080307.185186-6-axboe@kernel.dk


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 3ca5a356

io_uring/eventfd.c

+30 −11
Original line number Diff line number Diff line
@@ -47,6 +47,13 @@ static void io_eventfd_put(struct io_ev_fd *ev_fd) 
		call_rcu(&ev_fd->rcu, io_eventfd_free);

}



static void io_eventfd_release(struct io_ev_fd *ev_fd, bool put_ref)

{

	if (put_ref)

		io_eventfd_put(ev_fd);

	rcu_read_unlock();

}



/*

 * Returns true if the caller should put the ev_fd reference, false if not.

 */
@@ -74,14 +81,18 @@ static bool io_eventfd_trigger(struct io_ev_fd *ev_fd) 
	return false;

}



void io_eventfd_signal(struct io_ring_ctx *ctx)

/*

 * On success, returns with an ev_fd reference grabbed and the RCU read

 * lock held.

 */

static struct io_ev_fd *io_eventfd_grab(struct io_ring_ctx *ctx)

{

	struct io_ev_fd *ev_fd = NULL;

	struct io_ev_fd *ev_fd;



	if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)

		return;

		return NULL;



	guard(rcu)();

	rcu_read_lock();



	/*

	 * rcu_dereference ctx->io_ev_fd once and use it for both for checking
@@ -94,12 +105,20 @@ void io_eventfd_signal(struct io_ring_ctx *ctx) 
	 * completed between the NULL check of ctx->io_ev_fd at the start of

	 * the function and rcu_read_lock.

	 */

	if (!io_eventfd_trigger(ev_fd))

		return;

	if (!refcount_inc_not_zero(&ev_fd->refs))

		return;

	if (__io_eventfd_signal(ev_fd))

		io_eventfd_put(ev_fd);

	if (io_eventfd_trigger(ev_fd) && refcount_inc_not_zero(&ev_fd->refs))

		return ev_fd;



	rcu_read_unlock();

	return NULL;

}



void io_eventfd_signal(struct io_ring_ctx *ctx)

{

	struct io_ev_fd *ev_fd;



	ev_fd = io_eventfd_grab(ctx);

	if (ev_fd)

		io_eventfd_release(ev_fd, __io_eventfd_signal(ev_fd));

}



void io_eventfd_flush_signal(struct io_ring_ctx *ctx)