From 79a6cdeb7eb54e3d2d4bb9fc5f0231b057882a87 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Wed, 26 May 2010 14:43:36 -0700 Subject: [PATCH] cpuhotplug: do not need cpu_hotplug_begin() when CONFIG_HOTPLUG_CPU=n Since when CONFIG_HOTPLUG_CPU=n, get_online_cpus() do nothing, so we don't need cpu_hotplug_begin() either. This patch moves cpu_hotplug_begin()/cpu_hotplug_done() into the code block of CONFIG_HOTPLUG_CPU=y. Signed-off-by: Lai Jiangshan Cc: Gautham R Shenoy Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpu.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 0690ac2..63e8de1 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -20,6 +20,20 @@ /* Serializes the updates to cpu_online_mask, cpu_present_mask */ static DEFINE_MUTEX(cpu_add_remove_lock); +/* + * The following two API's must be used when attempting + * to serialize the updates to cpu_online_mask, cpu_present_mask. + */ +void cpu_maps_update_begin(void) +{ + mutex_lock(&cpu_add_remove_lock); +} + +void cpu_maps_update_done(void) +{ + mutex_unlock(&cpu_add_remove_lock); +} + static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain); /* If set, cpu_up and cpu_down will return -EBUSY and do nothing. @@ -27,6 +41,8 @@ static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain); */ static int cpu_hotplug_disabled; +#ifdef CONFIG_HOTPLUG_CPU + static struct { struct task_struct *active_writer; struct mutex lock; /* Synchronizes accesses to refcount, */ @@ -41,8 +57,6 @@ static struct { .refcount = 0, }; -#ifdef CONFIG_HOTPLUG_CPU - void get_online_cpus(void) { might_sleep(); @@ -67,22 +81,6 @@ void put_online_cpus(void) } EXPORT_SYMBOL_GPL(put_online_cpus); -#endif /* CONFIG_HOTPLUG_CPU */ - -/* - * The following two API's must be used when attempting - * to serialize the updates to cpu_online_mask, cpu_present_mask. - */ -void cpu_maps_update_begin(void) -{ - mutex_lock(&cpu_add_remove_lock); -} - -void cpu_maps_update_done(void) -{ - mutex_unlock(&cpu_add_remove_lock); -} - /* * This ensures that the hotplug operation can begin only when the * refcount goes to zero. @@ -124,6 +122,12 @@ static void cpu_hotplug_done(void) cpu_hotplug.active_writer = NULL; mutex_unlock(&cpu_hotplug.lock); } + +#else /* #if CONFIG_HOTPLUG_CPU */ +static void cpu_hotplug_begin(void) {} +static void cpu_hotplug_done(void) {} +#endif /* #esle #if CONFIG_HOTPLUG_CPU */ + /* Need to know about CPUs going up/down? */ int __ref register_cpu_notifier(struct notifier_block *nb) { -- 1.8.2.3