netdev - [PATCH 5/7] net: Fix bridgeing sysfs handling of rtnl

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Date:	Wed, 13 May 2009 20:00:41 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	David Miller <davem@...emloft.net>
Cc:	<netdev@...r.kernel.org>, Herbert Xu <herbert@...dor.apana.org.au>,
	Stephen Hemminger <shemminger@...tta.com>,
	Ben Greear <greearb@...delatech.com>,
	Patrick McHardy <kaber@...sh.net>
Subject: [PATCH 5/7] net: Fix bridgeing sysfs handling of rtnl_lock


Holding rtnl_lock when we are unregistering the sysfs files can
deadlock if we unconditionally take rtnl_lock in a sysfs file.  So fix
it with the now familiar patter of: rtnl_trylock and syscall_restart()

Signed-off-by: Eric W. Biederman <ebiederm@...stanetworks.com>
---
 net/bridge/br_sysfs_br.c |    3 ++-
 net/bridge/br_sysfs_if.c |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 603d892..ee4820a 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -172,7 +172,8 @@ static ssize_t store_stp_state(struct device *d,
 	if (endp == buf)
 		return -EINVAL;
 
-	rtnl_lock();
+	if (!rtnl_trylock())
+		return restart_syscall();
 	br_stp_set_enabled(br, val);
 	rtnl_unlock();
 
diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index 02b2d50..4a3cdf8 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -189,7 +189,8 @@ static ssize_t brport_store(struct kobject * kobj,
 
 	val = simple_strtoul(buf, &endp, 0);
 	if (endp != buf) {
-		rtnl_lock();
+		if (!rtnl_trylock())
+			return restart_syscall();
 		if (p->dev && p->br && brport_attr->store) {
 			spin_lock_bh(&p->br->lock);
 			ret = brport_attr->store(p, val);
-- 
1.6.0.6

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