From mboxrd@z Thu Jan  1 00:00:00 1970
From: John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH 1/4] [RFC] net: Explicitly initialize u64_stats_sync structures
 for lockdep
Date: Thu, 26 Sep 2013 12:34:30 -0700
Message-ID: <52448C46.2050107@linaro.org>
References: <1380220464-28840-1-git-send-email-john.stultz@linaro.org>	 <1380220464-28840-2-git-send-email-john.stultz@linaro.org> <1380223585.3165.205.camel@edumazet-glaptop>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Cc: LKML <linux-kernel@vger.kernel.org>,
	Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	Mirko Lindner <mlindner@marvell.com>,
	Stephen Hemminger <stephen@networkplumber.org>,
	Roger Luethi <rl@hellgate.ch>,
	Patrick McHardy <kaber@trash.net>,
	Rusty Russell <rusty@rustcorp.com.au>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	James Morris <jmorris@namei.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Wensong Zhang <wensong@linux-vs.org>,
	Simon Horman <horms@verge.net.au>,
	Julian Anastasov <ja@ssi.bg>, Jesse Gross <jesse@nicira.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"David S. Miller" <davem@davemloft.net>, netdev@vger.kernel.org,
	netfilter-devel@vger.kernel.org
To: Eric Dumazet <eric.dumazet@gmail.com>
Return-path: <netdev-owner@vger.kernel.org>
In-Reply-To: <1380223585.3165.205.camel@edumazet-glaptop>
Sender: netdev-owner@vger.kernel.org
List-Id: netfilter-devel.vger.kernel.org

On 09/26/2013 12:26 PM, Eric Dumazet wrote:
> On Thu, 2013-09-26 at 11:34 -0700, John Stultz wrote:
>> In order to enable lockdep on seqcount/seqlock structures, we
>> must explicitly initialize any locks.
>>
>> diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
>> index 8da8c4e..c450e11 100644
>> --- a/include/linux/u64_stats_sync.h
>> +++ b/include/linux/u64_stats_sync.h
>> @@ -67,6 +67,13 @@ struct u64_stats_sync {
>>  #endif
>>  };
>>  
>> +
>> +#if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
>> +#define u64_stats_init(syncp)	seqcount_init(syncp.seq)
>> +#else
>> +#define u64_stats_init(syncp)
>> +#endif
>> +
> I would prefer a function.
>
> static inline void u64_stats_init(struct u64_stats_sync *syncp)
> {
> #if BITS_PER_LONG == 32 && defined(CONFIG_SMP)
> 	seqcount_init(&syncp->seq);
> #endif
> }

No objection, though I worry that will obscure the lockdep key name,
causing all the u64_stat_sync locks to appear the same.

I'll give it a quick shot to see if the compiler inlines it well enough
to preserve the name.

thanks
-john