[PATCH net-next-2.6] net: speedup netdev_set_master()

[PATCH net-next-2.6] net: speedup netdev_set_master()

[Eric Dumazet]

We currently force a synchronize_net() in netdev_set_master()

This seems necessary only when a slave had a master and we dismantle it.

In the other case ("ifenslave bond0 ethO"), we dont need this long
delay.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
diff --git a/net/core/dev.c b/net/core/dev.c
index 17b1686..ff578ff 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3733,11 +3733,10 @@ int netdev_set_master(struct net_device *slave, struct net_device *master)
 
 	slave->master = master;
 
-	synchronize_net();
-
-	if (old)
+	if (old) {
+		synchronize_net();
 		dev_put(old);
-
+	}
 	if (master)
 		slave->flags |= IFF_SLAVE;
 	else

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Mar 2010 00:37:40 +0100

> We currently force a synchronize_net() in netdev_set_master()
> 
> This seems necessary only when a slave had a master and we dismantle it.
> 
> In the other case ("ifenslave bond0 ethO"), we dont need this long
> delay.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Depends upon the net-2.6 race fix?

Thanks for telling me :-/

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[Eric Dumazet]

Le jeudi 18 mars 2010 à 22:22 -0700, David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Fri, 19 Mar 2010 00:37:40 +0100
> 
> > We currently force a synchronize_net() in netdev_set_master()
> > 
> > This seems necessary only when a slave had a master and we dismantle it.
> > 
> > In the other case ("ifenslave bond0 ethO"), we dont need this long
> > delay.
> > 
> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> 
> Depends upon the net-2.6 race fix?
> 
> Thanks for telling me :-/

I believe it's not related. It's net-next-2.6 material, for sure :)

But yes, I discovered the race fix while studying netdev_set_master()

Thanks David

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Mar 2010 06:28:11 +0100

> Le jeudi 18 mars 2010 à 22:22 -0700, David Miller a écrit :
>> From: Eric Dumazet <eric.dumazet@gmail.com>
>> Date: Fri, 19 Mar 2010 00:37:40 +0100
>> 
>> > We currently force a synchronize_net() in netdev_set_master()
>> > 
>> > This seems necessary only when a slave had a master and we dismantle it.
>> > 
>> > In the other case ("ifenslave bond0 ethO"), we dont need this long
>> > delay.
>> > 
>> > Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
>> 
>> Depends upon the net-2.6 race fix?
>> 
>> Thanks for telling me :-/
> 
> I believe it's not related. It's net-next-2.6 material, for sure :)

It was not an issue of related, but rather "B won't apply cleanly
without A". Even line offsets can make "git apply" reject.

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[Eric Dumazet]

Le jeudi 18 mars 2010 à 22:36 -0700, David Miller a écrit :
> It was not an issue of related, but rather "B won't apply cleanly
> without A". Even line offsets can make "git apply" reject.
> --

I see, I can resubmit later if you prefer, once net-2.6 fix is pulled in
net-next, there is no hurry :)

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Mar 2010 06:45:13 +0100

> Le jeudi 18 mars 2010 à 22:36 -0700, David Miller a écrit :
>> It was not an issue of related, but rather "B won't apply cleanly
>> without A". Even line offsets can make "git apply" reject.
>> --
> 
> I see, I can resubmit later if you prefer, once net-2.6 fix is pulled in
> net-next, there is no hurry :)

No need, just let me know about this stuff in the future, that's
all :-)

Re: [PATCH net-next-2.6] net: speedup netdev_set_master()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Mar 2010 00:37:40 +0100

> We currently force a synchronize_net() in netdev_set_master()
> 
> This seems necessary only when a slave had a master and we dismantle it.
> 
> In the other case ("ifenslave bond0 ethO"), we dont need this long
> delay.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied.