Date: Sat, 4 May 2013 10:23:31 +0300 (EEST)
From: Julian Anastasov <ja@ssi.bg>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
cc: Peter Zijlstra <peterz@infradead.org>, Simon Horman <horms@verge.net.au>,
        Eric Dumazet <eric.dumazet@gmail.com>, Ingo Molnar <mingo@redhat.com>,
        lvs-devel@vger.kernel.org, netdev@vger.kernel.org,
        netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Dipankar Sarma <dipankar@in.ibm.com>
Subject: Re: [PATCH v2 1/2] sched: Add cond_resched_rcu_lock() helper
In-Reply-To: <20130503163045.GE3780@linux.vnet.ibm.com>
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	Hello,

On Fri, 3 May 2013, Paul E. McKenney wrote:

> static inline int cond_resched_rcu(void)
> {
> #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
> 	rcu_read_unlock();
> 	cond_resched();
> 	rcu_read_lock();
> #endif
> }
> 
> This adds absolutely no overhead in non-debug builds of CONFIG_PREEMPT_RCU,
> does the checking in debug builds, and allows voluntary preemption in
> !CONFIG_PREEMPT_RCU builds.  CONFIG_PROVE_RCU builds will check for an
> (illegal) outer rcu_read_lock() in CONFIG_PREEMPT_RCU builds, and you
> will get "scheduling while atomic" in response to an outer rcu_read_lock()
> in !CONFIG_PREEMPT_RCU builds.
> 
> It also seems to me a lot simpler.
> 
> Does this work, or am I still missing something?

	Works perfectly. Thanks! Tested CONFIG_PREEMPT_RCU=y/n,
the errors messages with extra RCU lock.

Regards

--
Julian Anastasov <ja@ssi.bg>
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