linux-kernel - [PATCH 2/4] net: don not detour through struct sock to find the poll waitqueue

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Message-Id: <20180730074213.16832-3-hch@lst.de>
Date:   Mon, 30 Jul 2018 09:42:11 +0200
From:   Christoph Hellwig <hch@....de>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] net: don not detour through struct sock to find the poll waitqueue

For any open socket file descriptor sock->sk->sk_wq->wait will always
point to sock->wq->wait.  That means we can do the shorter dereference
and removal a NULL check and don't have to not worry about any RCU
protection.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 include/net/sock.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 762069bb0d8c..7927541101a8 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2001,10 +2001,9 @@ static inline bool skwq_has_sleeper(struct socket_wq *wq)
 static inline void sock_poll_wait(struct file *filp, poll_table *p)
 {
 	struct socket *sock = filp->private_data;
-	wait_queue_head_t *wq = sk_sleep(sock->sk);
 
-	if (!poll_does_not_wait(p) && wq) {
-		poll_wait(filp, wq, p);
+	if (!poll_does_not_wait(p)) {
+		poll_wait(filp, &sock->wq->wait, p);
 		/* We need to be sure we are in sync with the
 		 * socket flags modification.
 		 *
-- 
2.18.0