x86/alternatives changes for v2.6.38

GIT PULL Ingo Molnar 1 participant 1 message Jan 6, 2011

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x86 CPU hotplug

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Ingo Molnar

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2011-01-06 10:22 UTC #0 lore raw

Linus,

Please pull the latest x86-alternatives-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-alternatives-for-linus

out-of-topic modifications in x86-alternatives-for-linus:
---------------------------------------------------------
kernel/cpu.c # 3fb82d5: x86, suspend: Avoid unnecessary s

Thanks,

Ingo

------------------>
Suresh Siddha (1):
x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume

 arch/x86/include/asm/alternative.h |    1 +
 arch/x86/kernel/alternative.c      |    3 ++-
 arch/x86/kernel/smpboot.c          |   14 ++++++++++++++
 kernel/cpu.c                       |   11 +++++++++++
 4 files changed, 28 insertions(+), 1 deletions(-)

arch/x86/include/asm/alternative.h +1 -0

index 76561d2..01171f6 100644
@@ -66,6 +66,7 @@ extern void alternatives_smp_module_add(struct module *mod, char *name,
 extern void alternatives_smp_module_del(struct module *mod);
 extern void alternatives_smp_switch(int smp);
 extern int alternatives_text_reserved(void *start, void *end);
+extern bool skip_smp_alternatives;
 #else
 static inline void alternatives_smp_module_add(struct module *mod, char *name,
 					       void *locks, void *locks_end,

arch/x86/kernel/alternative.c +2 -1

index 5079f24..9f98eb4 100644
@@ -353,6 +353,7 @@ void __init_or_module alternatives_smp_module_del(struct module *mod)
 	mutex_unlock(&smp_alt);
 }
 
+bool skip_smp_alternatives;
 void alternatives_smp_switch(int smp)
 {
 	struct smp_alt_module *mod;

@@ -368,7 +369,7 @@ void alternatives_smp_switch(int smp)
 	printk("lockdep: fixing up alternatives.\n");
 #endif
 
-	if (noreplace_smp || smp_alt_once)
+	if (noreplace_smp || smp_alt_once || skip_smp_alternatives)
 		return;
 	BUG_ON(!smp && (num_online_cpus() > 1));

arch/x86/kernel/smpboot.c +14 -0

index 083e99d..837c81e 100644
@@ -1166,6 +1166,20 @@ out:
 	preempt_enable();
 }
 
+void arch_disable_nonboot_cpus_begin(void)
+{
+	/*
+	 * Avoid the smp alternatives switch during the disable_nonboot_cpus().
+	 * In the suspend path, we will be back in the SMP mode shortly anyways.
+	 */
+	skip_smp_alternatives = true;
+}
+
+void arch_disable_nonboot_cpus_end(void)
+{
+	skip_smp_alternatives = false;
+}
+
 void arch_enable_nonboot_cpus_begin(void)
 {
 	set_mtrr_aps_delayed_init();

kernel/cpu.c +11 -0

index f6e726f..8ccc182 100644
@@ -386,6 +386,14 @@ out:
 #ifdef CONFIG_PM_SLEEP_SMP
 static cpumask_var_t frozen_cpus;
 
+void __weak arch_disable_nonboot_cpus_begin(void)
+{
+}
+
+void __weak arch_disable_nonboot_cpus_end(void)
+{
+}
+
 int disable_nonboot_cpus(void)
 {
 	int cpu, first_cpu, error = 0;

@@ -397,6 +405,7 @@ int disable_nonboot_cpus(void)
 	 * with the userspace trying to use the CPU hotplug at the same time
 	 */
 	cpumask_clear(frozen_cpus);
+	arch_disable_nonboot_cpus_begin();
 
 	printk("Disabling non-boot CPUs ...\n");
 	for_each_online_cpu(cpu) {

@@ -412,6 +421,8 @@ int disable_nonboot_cpus(void)
 		}
 	}
 
+	arch_disable_nonboot_cpus_end();
+
 	if (!error) {
 		BUG_ON(num_online_cpus() > 1);
 		/* Make sure the CPUs won't be enabled by someone else */