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From: Oleg Nesterov <[email protected]>
To: Christian Brauner <[email protected]>,
	Linus Torvalds <[email protected]>,
	Manfred Spraul <[email protected]>
Cc: "David S. Miller" <[email protected]>,
	Eric Dumazet <[email protected]>, Jens Axboe <[email protected]>,
	Pavel Begunkov <[email protected]>,
	WangYuli <[email protected]>,
	[email protected], [email protected],
	[email protected]
Subject: [PATCH 2/5] poll_wait: kill the obsolete wait_address check
Date: Tue, 7 Jan 2025 17:27:24 +0100	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

This check is historical and no longer needed, wait_address is never NULL.
These days we rely on the poll_table->_qproc check. NULL if select/poll
is not going to sleep, or it already has a data to report, or all waiters
have already been registered after the 1st iteration.

However, poll_table *p can be NULL, see p9_fd_poll() for example, so we
can't remove the "p != NULL" check.

Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Oleg Nesterov <[email protected]>
---
 include/linux/poll.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/poll.h b/include/linux/poll.h
index fc641b50f129..57b6d1ccd8bf 100644
--- a/include/linux/poll.h
+++ b/include/linux/poll.h
@@ -41,7 +41,7 @@ typedef struct poll_table_struct {
 
 static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
 {
-	if (p && p->_qproc && wait_address) {
+	if (p && p->_qproc) {
 		p->_qproc(filp, wait_address, p);
 		/*
 		 * This memory barrier is paired in the wq_has_sleeper().
-- 
2.25.1.362.g51ebf55


  parent reply	other threads:[~2025-01-07 16:28 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-07 16:26 [PATCH 0/5] poll_wait: add mb() to fix theoretical race between waitqueue_active() and .poll() Oleg Nesterov
2025-01-07 16:27 ` [PATCH 1/5] " Oleg Nesterov
2025-01-07 16:27 ` Oleg Nesterov [this message]
2025-01-07 16:27 ` [PATCH 3/5] io_uring_poll: kill the no longer necessary barrier after poll_wait() Oleg Nesterov
2025-01-07 16:27 ` [PATCH 4/5] sock_poll_wait: " Oleg Nesterov
2025-01-07 16:27 ` [PATCH 5/5] poll: kill poll_does_not_wait() Oleg Nesterov
2025-01-07 17:38 ` [PATCH 0/5] poll_wait: add mb() to fix theoretical race between waitqueue_active() and .poll() Linus Torvalds
2025-01-07 22:55   ` Jens Axboe
2025-01-10 10:56   ` Christian Brauner
2025-01-10 11:00 ` Christian Brauner

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