[PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[Eric Dumazet]

Avoid dev_hold()/dev_put() in sock_bindtodevice()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
 net/core/sock.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 5a51512..38820ea 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -420,14 +420,16 @@ static int sock_bindtodevice(struct sock *sk, char __user *optval, int optlen)
 	if (devname[0] == '\0') {
 		index = 0;
 	} else {
-		struct net_device *dev = dev_get_by_name(net, devname);
+		struct net_device *dev;
 
+		rcu_read_lock();
+		dev = dev_get_by_name_rcu(net, devname);
+		if (dev)
+			index = dev->ifindex;
+		rcu_read_unlock();
 		ret = -ENODEV;
 		if (!dev)
 			goto out;
-
-		index = dev->ifindex;
-		dev_put(dev);
 	}
 
 	lock_sock(sk);

Re: [PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 04 Nov 2009 23:36:44 +0100

> Avoid dev_hold()/dev_put() in sock_bindtodevice()
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied to net-next-2.6, thanks.

Re: [PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Thu, 05 Nov 2009 21:08:30 -0800 (PST)

> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Wed, 04 Nov 2009 23:36:44 +0100
> 
>> Avoid dev_hold()/dev_put() in sock_bindtodevice()
>> 
>> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> 
> Applied to net-next-2.6, thanks.

Eric I had to add the following patch to cure a build
warning after this, just FYI:

net: Fix build warning in sock_bindtodevice().

net/core/sock.c: In function 'sock_setsockopt':
net/core/sock.c:396: warning: 'index' may be used uninitialized in this function
net/core/sock.c:396: note: 'index' was declared here

GCC can't see that all paths initialize index, so just
set it to the default (0) and eliminate the specific
code block that handles the null device name string.

Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/core/sock.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index 38820ea..76ff58d 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -417,9 +417,8 @@ static int sock_bindtodevice(struct sock *sk, char __user *optval, int optlen)
 	if (copy_from_user(devname, optval, optlen))
 		goto out;
 
-	if (devname[0] == '\0') {
-		index = 0;
-	} else {
+	index = 0;
+	if (devname[0] != '\0') {
 		struct net_device *dev;
 
 		rcu_read_lock();
-- 
1.6.5.2

Re: [PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[Eric Dumazet]

David Miller a écrit :
> From: David Miller <davem@davemloft.net>
> Date: Thu, 05 Nov 2009 21:08:30 -0800 (PST)
> 
>> From: Eric Dumazet <eric.dumazet@gmail.com>
>> Date: Wed, 04 Nov 2009 23:36:44 +0100
>>
>>> Avoid dev_hold()/dev_put() in sock_bindtodevice()
>>>
>>> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
>> Applied to net-next-2.6, thanks.
> 
> Eric I had to add the following patch to cure a build
> warning after this, just FYI:
> 
> net: Fix build warning in sock_bindtodevice().
> 
> net/core/sock.c: In function 'sock_setsockopt':
> net/core/sock.c:396: warning: 'index' may be used uninitialized in this function
> net/core/sock.c:396: note: 'index' was declared here
> 
> GCC can't see that all paths initialize index, so just
> set it to the default (0) and eliminate the specific
> code block that handles the null device name string.
> 

Thanks David, which gcc version are you using ?

Re: [PATCH net-next-2.6] net: sock_bindtodevice() RCU-ification

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 06 Nov 2009 08:08:59 +0100

> Thanks David, which gcc version are you using ?

I'm using "gcc-4.2.4 (Ubuntu 4.2.4-1ubuntu3)" on sparc.