[PATCH net] ip_tunnel: fix preempt warning in ip tunnel creation/updating

[PATCH net] ip_tunnel: fix preempt warning in ip tunnel creation/updating

[Paolo Abeni]

After the commit e09acddf873b ("ip_tunnel: replace dst_cache with generic
implementation"), a preemption debug warning is triggered on ip4
tunnels updating; the dst cache helper needs to be invoked in unpreemptible
context.

We don't need to load the cache on tunnel update, so this commit fixes
the warning replacing the load with a dst cache reset, which is
preempt safe.

Fixes: e09acddf873b ("ip_tunnel: replace dst_cache with generic
implementation")

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/ipv4/ip_tunnel.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 6aad019..a69ed94 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -326,12 +326,12 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
 		if (!IS_ERR(rt)) {
 			tdev = rt->dst.dev;
-			dst_cache_set_ip4(&tunnel->dst_cache, &rt->dst,
-					  fl4.saddr);
 			ip_rt_put(rt);
 		}
 		if (dev->type != ARPHRD_ETHER)
 			dev->flags |= IFF_POINTOPOINT;
+
+		dst_cache_reset(&tunnel->dst_cache);
 	}
 
 	if (!tdev && tunnel->parms.link)
-- 
1.8.3.1

Re: [PATCH net] ip_tunnel: fix preempt warning in ip tunnel creation/updating

[Eric Dumazet]

On Thu, 2016-04-28 at 11:04 +0200, Paolo Abeni wrote:
> After the commit e09acddf873b ("ip_tunnel: replace dst_cache with generic
> implementation"), a preemption debug warning is triggered on ip4
> tunnels updating; the dst cache helper needs to be invoked in unpreemptible
> context.
> 
> We don't need to load the cache on tunnel update, so this commit fixes
> the warning replacing the load with a dst cache reset, which is
> preempt safe.
> 
> Fixes: e09acddf873b ("ip_tunnel: replace dst_cache with generic
> implementation")
> 
> Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---

Seems good to me, thanks.

Note that the Fixes: tag should not be followed by a blank line.
(And presumably no line wrap is necessary)
It really is part of the standard set of tags.
They should be grouped together.

Acked-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH net] ip_tunnel: fix preempt warning in ip tunnel creation/updating

[Paolo Abeni]

On Thu, 2016-04-28 at 05:09 -0700, Eric Dumazet wrote:
> On Thu, 2016-04-28 at 11:04 +0200, Paolo Abeni wrote:
> > After the commit e09acddf873b ("ip_tunnel: replace dst_cache with generic
> > implementation"), a preemption debug warning is triggered on ip4
> > tunnels updating; the dst cache helper needs to be invoked in unpreemptible
> > context.
> > 
> > We don't need to load the cache on tunnel update, so this commit fixes
> > the warning replacing the load with a dst cache reset, which is
> > preempt safe.
> > 
> > Fixes: e09acddf873b ("ip_tunnel: replace dst_cache with generic
> > implementation")
> > 
> > Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
> > Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> > ---
> 
> Seems good to me, thanks.
> 
> Note that the Fixes: tag should not be followed by a blank line.
> (And presumably no line wrap is necessary)
> It really is part of the standard set of tags.
> They should be grouped together.

Oops, I missed that points and checkpatch.pl did not help. 
Thank you for the advice.

Paolo

Re: [PATCH net] ip_tunnel: fix preempt warning in ip tunnel creation/updating

[David Miller]

From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 28 Apr 2016 11:04:51 +0200

> After the commit e09acddf873b ("ip_tunnel: replace dst_cache with generic
> implementation"), a preemption debug warning is triggered on ip4
> tunnels updating; the dst cache helper needs to be invoked in unpreemptible
> context.
> 
> We don't need to load the cache on tunnel update, so this commit fixes
> the warning replacing the load with a dst cache reset, which is
> preempt safe.
> 
> Fixes: e09acddf873b ("ip_tunnel: replace dst_cache with generic
> implementation")
> 
> Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Applied, thanks Paolo.