Re: [PATCH] irda: Fix RCU lock pairing on error path

["Paul E. McKenney" <paulmck@us.ibm.com>]

On Wed, Jun 28, 2006 at 05:56:41PM -0700, Josh Triplett wrote:
> irlan_client_discovery_indication calls rcu_read_lock and rcu_read_unlock, but
> returns without unlocking in an error case.  Fix that by replacing the return
> with a goto so that the rcu_read_unlock always gets executed.

Good catch!!!  Looks good from an RCU viewpoint, in fact, looks absolutely
necessary to permit IRDA to work in debug mode, particularly in either
a CONFIG_PREEMPT or a -rt kernel.

One question below, but up to the maintainer.  ;-)

							Thanx, Paul

Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
> Signed-off-by: Josh Triplett <josh@freedesktop.org>
> 
> ---
> 
>  net/irda/irlan/irlan_client.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> e20ab96944814489277c3bfd4e69133854ab01e9
> diff --git a/net/irda/irlan/irlan_client.c b/net/irda/irlan/irlan_client.c
> index f8e6cb0..5ce7d2e 100644
> --- a/net/irda/irlan/irlan_client.c
> +++ b/net/irda/irlan/irlan_client.c
> @@ -173,13 +173,14 @@ void irlan_client_discovery_indication(d
>  	rcu_read_lock();
>  	self = irlan_get_any();
>  	if (self) {
> -		IRDA_ASSERT(self->magic == IRLAN_MAGIC, return;);
> +		IRDA_ASSERT(self->magic == IRLAN_MAGIC, goto out;);
>  
>  		IRDA_DEBUG(1, "%s(), Found instance (%08x)!\n", __FUNCTION__ ,
>  		      daddr);
>  		
>  		irlan_client_wakeup(self, saddr, daddr);
>  	}
> +out:

Should the above label instead be as follows?

	IRDA_ASSERT_LABEL(out:)

Just in case some variant of gcc, sparse, or whatever complains about
labels that don't have a corresponding goto (in CONFIG_IRDA_DEBUG=n
builds).

>  	rcu_read_unlock();
>  }
>  	
> 
>