linux-kernel - [PATCH 2/5] poll_wait: kill the obsolete wait

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Message-ID: <20250107162724.GA18926@redhat.com>
Date: Tue, 7 Jan 2025 17:27:24 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Christian Brauner <brauner@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Manfred Spraul <manfred@...orfullife.com>
Cc: "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Jens Axboe <axboe@...nel.dk>,
	Pavel Begunkov <asml.silence@...il.com>,
	WangYuli <wangyuli@...ontech.com>, linux-kernel@...r.kernel.org,
	io-uring@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH 2/5] poll_wait: kill the obsolete wait_address check

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/20250106180325.GF7233@redhat.com/
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 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