linux-kernel - [PATCH -v2] ipvs: Remove unused variable ret from sync_thread

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Message-Id: <1384266864-564-1-git-send-email-geert@linux-m68k.org>
Date:	Tue, 12 Nov 2013 15:34:24 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Peter Zijlstra <peterz@...radead.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...nel.org>, Julian Anastasov <ja@....bg>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH -v2] ipvs: Remove unused variable ret from sync_thread_master()

net/netfilter/ipvs/ip_vs_sync.c: In function 'sync_thread_master':
net/netfilter/ipvs/ip_vs_sync.c:1640:8: warning: unused variable 'ret' [-Wunused-variable]

Commit 35a2af94c7ce7130ca292c68b1d27fcfdb648f6b ("sched/wait: Make the
__wait_event*() interface more friendly") changed how the interruption
state is returned. However, sync_thread_master() ignores this state,
now causing a compile warning.

According to Julian Anastasov <ja@....bg>, this behavior is OK:

    "Yes, your patch looks ok to me. In the past we used ssleep() but IPVS
     users were confused why IPVS threads increase the load average. So, we
     switched to _interruptible calls and later the socket polling was
     added."

Document this, as requested by Peter Zijlstra, to avoid precious developers
disappearing in this pitfall in the future.

Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
v2: Document that sync_thread_master() ignores the interruption state,

 net/netfilter/ipvs/ip_vs_sync.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
index f63c2388f38d..db801263ee9f 100644
--- a/net/netfilter/ipvs/ip_vs_sync.c
+++ b/net/netfilter/ipvs/ip_vs_sync.c
@@ -1637,7 +1637,10 @@ static int sync_thread_master(void *data)
 			continue;
 		}
 		while (ip_vs_send_sync_msg(tinfo->sock, sb->mesg) < 0) {
-			int ret = __wait_event_interruptible(*sk_sleep(sk),
+			/* (Ab)use interruptible sleep to avoid increasing
+			 * the load avg.
+			 */
+			__wait_event_interruptible(*sk_sleep(sk),
 						   sock_writeable(sk) ||
 						   kthread_should_stop());
 			if (unlikely(kthread_should_stop()))
-- 
1.7.9.5

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