netdev - [PATCH 1/2] ipv4 igmp: use in_dev_put in timer handlers instead of __in_dev

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Date:	Sun, 29 Sep 2013 13:39:42 -0700
From:	Salam Noureddine <noureddine@...stanetworks.com>
To:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org
Cc:	Salam Noureddine <noureddine@...stanetworks.com>
Subject: [PATCH 1/2] ipv4 igmp: use in_dev_put in timer handlers instead of __in_dev_put

It is possible for the timer handlers to run after the call to
ip_mc_down so use in_dev_put instead of __in_dev_put in the handler
function in order to do proper cleanup when the refcnt reaches 0.
Otherwise, the refcnt can reach zero without the in_device being
destroyed and we end up leaking a reference to the net_device and
see messages like the following,

unregister_netdevice: waiting for eth0 to become free. Usage count = 1

Tested on linux-3.4.43.

Signed-off-by: Salam Noureddine <noureddine@...stanetworks.com>
---
 net/ipv4/igmp.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index dace87f..7defdc9 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -736,7 +736,7 @@ static void igmp_gq_timer_expire(unsigned long data)
 
 	in_dev->mr_gq_running = 0;
 	igmpv3_send_report(in_dev, NULL);
-	__in_dev_put(in_dev);
+	in_dev_put(in_dev);
 }
 
 static void igmp_ifc_timer_expire(unsigned long data)
@@ -749,7 +749,7 @@ static void igmp_ifc_timer_expire(unsigned long data)
 		igmp_ifc_start_timer(in_dev,
 				     unsolicited_report_interval(in_dev));
 	}
-	__in_dev_put(in_dev);
+	in_dev_put(in_dev);
 }
 
 static void igmp_ifc_event(struct in_device *in_dev)
-- 
1.7.4.4

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