Re: [net-next:master 257/266] drivers/net/team/team_mode_loadbalance.c:99:30: sparse: incompatible types in comparison expression (different address spaces)

Re: [net-next:master 257/266] drivers/net/team/team_mode_loadbalance.c:99:30: sparse: incompatible types in comparison expression (different address spaces)

[Eric Dumazet]

On Wed, 2012-06-20 at 05:49 -0700, Paul E. McKenney wrote:
> On Wed, Jun 20, 2012 at 02:50:55PM +0800, Fengguang Wu wrote:
> > [CC Paul, the RCU maintainer]
> > 
> > On Wed, Jun 20, 2012 at 08:36:07AM +0200, Jiri Pirko wrote:
> > > Wed, Jun 20, 2012 at 06:27:43AM CEST, wfg@linux.intel.com wrote:
> > > >Hi Jiri,
> > > >
> > > >There are new sparse warnings show up in
> > > >
> > > >tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
> > > >head:   677a3d60fb3153f786a0d28fcf0287670e7bd3c2
> > > >commit: ab8250d70063f77929fc404c02390a1f64d66416 [257/266] team: lb: introduce infrastructure for userspace driven tx loadbalancing
> > > >
> > > >All sparse warnings:
> > > >
> > > >drivers/net/team/team_mode_loadbalance.c:99:30: sparse: incompatible types in comparison expression (different address spaces)
> > > >
> > > >drivers/net/team/team_mode_loadbalance.c:99:
> > > >    96			struct lb_port_mapping *pm;
> > > >    97	
> > > >    98			pm = &lb_priv->ex->tx_hash_to_port_mapping[i];
> > > >  > 99			if (pm->port == port) {
> > > 
> > > This looks like your checker does not like
> > > (struct team_port __rcu *) == (struct team_port *)
> > > But I wonder why (or how should I fix that)
> 
> Because you said that it was an RCU-protected pointer, but then did
> not use an RCU primitive to access it.  In this case, where you are
> just using the value but not dereferencing it, you can use
> rcu_access_pointer().

Yes, and please Jiri change the 

rcu_assign_pointer(pm->port, NULL);

by

RCU_INIT_POINTER(pm->port, NULL);

Re: [net-next:master 257/266] drivers/net/team/team_mode_loadbalance.c:99:30: sparse: incompatible types in comparison expression (different address spaces)

[Jiri Pirko]

Wed, Jun 20, 2012 at 03:11:49PM CEST, eric.dumazet@gmail.com wrote:
>On Wed, 2012-06-20 at 05:49 -0700, Paul E. McKenney wrote:
>> On Wed, Jun 20, 2012 at 02:50:55PM +0800, Fengguang Wu wrote:
>> > [CC Paul, the RCU maintainer]
>> > 
>> > On Wed, Jun 20, 2012 at 08:36:07AM +0200, Jiri Pirko wrote:
>> > > Wed, Jun 20, 2012 at 06:27:43AM CEST, wfg@linux.intel.com wrote:
>> > > >Hi Jiri,
>> > > >
>> > > >There are new sparse warnings show up in
>> > > >
>> > > >tree:   git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git master
>> > > >head:   677a3d60fb3153f786a0d28fcf0287670e7bd3c2
>> > > >commit: ab8250d70063f77929fc404c02390a1f64d66416 [257/266] team: lb: introduce infrastructure for userspace driven tx loadbalancing
>> > > >
>> > > >All sparse warnings:
>> > > >
>> > > >drivers/net/team/team_mode_loadbalance.c:99:30: sparse: incompatible types in comparison expression (different address spaces)
>> > > >
>> > > >drivers/net/team/team_mode_loadbalance.c:99:
>> > > >    96			struct lb_port_mapping *pm;
>> > > >    97	
>> > > >    98			pm = &lb_priv->ex->tx_hash_to_port_mapping[i];
>> > > >  > 99			if (pm->port == port) {
>> > > 
>> > > This looks like your checker does not like
>> > > (struct team_port __rcu *) == (struct team_port *)
>> > > But I wonder why (or how should I fix that)
>> 
>> Because you said that it was an RCU-protected pointer, but then did
>> not use an RCU primitive to access it.  In this case, where you are
>> just using the value but not dereferencing it, you can use
>> rcu_access_pointer().
>
>Yes, and please Jiri change the 
>
>rcu_assign_pointer(pm->port, NULL);
>
>by
>
>RCU_INIT_POINTER(pm->port, NULL);

Will do.

>
>
>