Re: [PATCH 4/4] [RFC] ipv6: Fix for possible ipv6 seqlock deadlock

[Eric Dumazet]

On Thu, 2013-09-26 at 11:34 -0700, John Stultz wrote:
> While enabling lockdep on seqlocks, I ran accross the warning below
> caused by the ipv6 stats being updated in both irq and non-irq context.
> 
> This is a novice attempt to correct the issue, and with this patch
> the warning goes away. Any better solutions would be appreciated!

...

>  
>  out_err_release:
> -	if (err == -ENETUNREACH)
> +	if (err == -ENETUNREACH) {
> +		unsigned long flags;
> +		/* some of the stats are locked in irq context */
> +		local_irq_save(flags);
>  		IP6_INC_STATS_BH(net, NULL, IPSTATS_MIB_OUTNOROUTES);
> +		local_irq_restore(flags);
> +	}
>  	dst_release(*dst);
>  	*dst = NULL;
>  	return err;

You better change IP6_INC_STATS_BH() to IP6_INC_STATS()

On x86 for example, no extra code will be generated (no need to disable
hard or soft irqs)



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/