Unverified Commit 4e15fa83 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Christian Brauner
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io_uring_poll: kill the no longer necessary barrier after poll_wait() 



Now that poll_wait() provides a full barrier we can remove smp_rmb() from
io_uring_poll().

In fact I don't think smp_rmb() was correct, it can't serialize LOADs and
STOREs.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250107162730.GA18940@redhat.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 10b02a2c

io_uring/io_uring.c

+4 −5
Original line number Diff line number Diff line
@@ -2809,13 +2809,12 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait) 


	if (unlikely(!ctx->poll_activated))

		io_activate_pollwq(ctx);



	poll_wait(file, &ctx->poll_wq, wait);

	/*

	 * synchronizes with barrier from wq_has_sleeper call in

	 * io_commit_cqring

	 * provides mb() which pairs with barrier from wq_has_sleeper

	 * call in io_commit_cqring

	 */

	smp_rmb();

	poll_wait(file, &ctx->poll_wq, wait);



	if (!io_sqring_full(ctx))

		mask |= EPOLLOUT | EPOLLWRNORM;