linux-kernel - Re: [RFC PATCH v1 13/70] x86, x2apic_cluster:

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Date:	Mon, 28 Jul 2014 02:04:55 -0400
From:	"Chen, Gong" <gong.chen@...ux.intel.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org, tglx@...utronix.de,
	paulus@...ba.org, benh@...nel.crashing.org, tony.luck@...el.com,
	hpa@...or.com, jkosina@...e.cz, rafael.j.wysocki@...el.com,
	linux@....linux.org.uk, ralf@...ux-mips.org,
	schwidefsky@...ibm.com, davem@...emloft.net,
	viro@...iv.linux.org.uk, fweisbec@...il.com, cl@...ux.com,
	akpm@...ux-foundation.org, axboe@...nel.dk,
	JBottomley@...allels.com, neilb@...e.de,
	christoffer.dall@...aro.org, rostedt@...dmis.org, rric@...nel.org,
	gregkh@...uxfoundation.org, mhocko@...e.cz, david@...morbit.com
Subject: Re: [RFC PATCH v1 13/70] x86, x2apic_cluster: _FROZEN Cleanup

On Wed, Jul 23, 2014 at 10:36:28PM +0200, Borislav Petkov wrote:
> Those checks dealing with CPU_TASKS_FROZEN in-between make the whole
> switch statement hard to follow.
> 
> How about we go a step further and deal with CPU_UP_CANCELED_FROZEN
> upfront and even simplify the rest:
> 

--------8<--------
Subject: [RFC PATCH v2 13/70] x86, x2apic_cluster: _FROZEN Cleanup

Remove XXX_FROZEN state from x86/x2apic_cluster.

Signed-off-by: Chen, Gong <gong.chen@...ux.intel.com>
Suggested-by: Borislav Petkov <bp@...en8.de>
---
 arch/x86/kernel/apic/x2apic_cluster.c | 37 +++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index e66766b..b8a6ea8 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -144,6 +144,20 @@ static void init_x2apic_ldr(void)
 	}
 }
 
+static void __update_clusterinfo(unsigned int this_cpu)
+{
+	unsigned int cpu;
+
+	for_each_online_cpu(cpu) {
+		if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
+			continue;
+		__cpu_clear(this_cpu, per_cpu(cpus_in_cluster, cpu));
+		__cpu_clear(cpu, per_cpu(cpus_in_cluster, this_cpu));
+	}
+	free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
+	free_cpumask_var(per_cpu(ipi_mask, this_cpu));
+}
+
  /*
   * At CPU state changes, update the x2apic cluster sibling info.
   */
@@ -151,34 +165,31 @@ static int
 update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
 	unsigned int this_cpu = (unsigned long)hcpu;
-	unsigned int cpu;
 	int err = 0;
 
 	switch (action) {
 	case CPU_UP_PREPARE:
 		if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, this_cpu),
-					GFP_KERNEL)) {
+					GFP_KERNEL))
 			err = -ENOMEM;
-		} else if (!zalloc_cpumask_var(&per_cpu(ipi_mask, this_cpu),
-					       GFP_KERNEL)) {
+		else if (!zalloc_cpumask_var(&per_cpu(ipi_mask, this_cpu),
+					     GFP_KERNEL)) {
 			free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
 			err = -ENOMEM;
 		}
 		break;
 	case CPU_UP_CANCELED:
-	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
-		for_each_online_cpu(cpu) {
-			if (x2apic_cluster(this_cpu) != x2apic_cluster(cpu))
-				continue;
-			__cpu_clear(this_cpu, per_cpu(cpus_in_cluster, cpu));
-			__cpu_clear(cpu, per_cpu(cpus_in_cluster, this_cpu));
-		}
-		free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
-		free_cpumask_var(per_cpu(ipi_mask, this_cpu));
+		__update_clusterinfo(this_cpu);
+		break;
+	default:
 		break;
 	}
 
+	if (test_and_clear_bit(CPU_TASKS_FROZEN, &action) &&
+	    (action == CPU_UP_CANCELED))
+		__update_clusterinfo(this_cpu);
+
 	return notifier_from_errno(err);
 }
 
-- 
2.0.0.rc2

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