linux-kernel - Re: [PATCH -rcu dev 1/3] rcu/tree: tick_dep_set/clear

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Date:   Fri, 16 Aug 2019 13:35:04 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     "Paul E. McKenney" <paulmck@...ux.ibm.com>
Cc:     linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
        frederic@...nel.org
Subject: Re: [PATCH -rcu dev 1/3] rcu/tree: tick_dep_set/clear_cpu should
 accept bits instead of masks

On Fri, Aug 16, 2019 at 10:25:29AM -0700, Paul E. McKenney wrote:
> On Thu, Aug 15, 2019 at 10:53:09PM -0400, Joel Fernandes (Google) wrote:
> > This commit fixes the issue.
> > 
> > Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> 
> And I am squashing these into their respective commits with attribution.
> Good eyes, thank you very much!!!

Thank you!!

 - Joel

> 							Thanx, Paul
> 
> > ---
> >  kernel/rcu/tree.c | 29 +++++++++++++++++------------
> >  1 file changed, 17 insertions(+), 12 deletions(-)
> > 
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index 0512de9ead20..322b1b57967c 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -829,7 +829,7 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
> >  		   !rdp->dynticks_nmi_nesting &&
> >  		   rdp->rcu_urgent_qs && !rdp->rcu_forced_tick) {
> >  		rdp->rcu_forced_tick = true;
> > -		tick_dep_set_cpu(rdp->cpu, TICK_DEP_MASK_RCU);
> > +		tick_dep_set_cpu(rdp->cpu, TICK_DEP_BIT_RCU);
> >  	}
> >  	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
> >  			  rdp->dynticks_nmi_nesting,
> > @@ -898,7 +898,7 @@ void rcu_irq_enter_irqson(void)
> >  void rcu_disable_tick_upon_qs(struct rcu_data *rdp)
> >  {
> >  	if (tick_nohz_full_cpu(rdp->cpu) && rdp->rcu_forced_tick) {
> > -		tick_dep_clear_cpu(rdp->cpu, TICK_DEP_MASK_RCU);
> > +		tick_dep_clear_cpu(rdp->cpu, TICK_DEP_BIT_RCU);
> >  		rdp->rcu_forced_tick = false;
> >  	}
> >  }
> > @@ -2123,8 +2123,9 @@ int rcutree_dead_cpu(unsigned int cpu)
> >  	do_nocb_deferred_wakeup(per_cpu_ptr(&rcu_data, cpu));
> >  
> >  	// Stop-machine done, so allow nohz_full to disable tick.
> > -	for_each_online_cpu(c)
> > -		tick_dep_clear_cpu(c, TICK_DEP_MASK_RCU);
> > +	for_each_online_cpu(c) {
> > +		tick_dep_clear_cpu(c, TICK_DEP_BIT_RCU);
> > +	}
> >  	return 0;
> >  }
> >  
> > @@ -2175,8 +2176,9 @@ static void rcu_do_batch(struct rcu_data *rdp)
> >  	rcu_nocb_unlock_irqrestore(rdp, flags);
> >  
> >  	/* Invoke callbacks. */
> > -	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
> > -		tick_dep_set_task(current, TICK_DEP_MASK_RCU);
> > +	if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
> > +		tick_dep_set_task(current, TICK_DEP_BIT_RCU);
> > +	}
> >  	rhp = rcu_cblist_dequeue(&rcl);
> >  	for (; rhp; rhp = rcu_cblist_dequeue(&rcl)) {
> >  		debug_rcu_head_unqueue(rhp);
> > @@ -2243,8 +2245,9 @@ static void rcu_do_batch(struct rcu_data *rdp)
> >  	/* Re-invoke RCU core processing if there are callbacks remaining. */
> >  	if (!offloaded && rcu_segcblist_ready_cbs(&rdp->cblist))
> >  		invoke_rcu_core();
> > -	if (IS_ENABLED(CONFIG_NO_HZ_FULL))
> > -		tick_dep_clear_task(current, TICK_DEP_MASK_RCU);
> > +	if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
> > +		tick_dep_clear_task(current, TICK_DEP_BIT_RCU);
> > +	}
> >  }
> >  
> >  /*
> > @@ -3118,8 +3121,9 @@ int rcutree_online_cpu(unsigned int cpu)
> >  	rcutree_affinity_setting(cpu, -1);
> >  
> >  	// Stop-machine done, so allow nohz_full to disable tick.
> > -	for_each_online_cpu(c)
> > -		tick_dep_clear_cpu(c, TICK_DEP_MASK_RCU);
> > +	for_each_online_cpu(c) {
> > +		tick_dep_clear_cpu(c, TICK_DEP_BIT_RCU);
> > +	}
> >  	return 0;
> >  }
> >  
> > @@ -3143,8 +3147,9 @@ int rcutree_offline_cpu(unsigned int cpu)
> >  	rcutree_affinity_setting(cpu, cpu);
> >  
> >  	// nohz_full CPUs need the tick for stop-machine to work quickly
> > -	for_each_online_cpu(c)
> > -		tick_dep_set_cpu(c, TICK_DEP_MASK_RCU);
> > +	for_each_online_cpu(c) {
> > +		tick_dep_set_cpu(c, TICK_DEP_BIT_RCU);
> > +	}
> >  	return 0;
> >  }
> >  
> > -- 
> > 2.23.0.rc1.153.gdeed80330f-goog
> > 
>