The patch titled cpuhotplug: do not need cpu_hotplug_begin() when CONFIG_HOTPLUG_CPU=n has been added to the -mm tree. Its filename is cpuhotplug-do-not-need-cpu_hotplug_begin-when-config_hotplug_cpu=n.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: cpuhotplug: do not need cpu_hotplug_begin() when CONFIG_HOTPLUG_CPU=n From: Lai Jiangshan <laijs@xxxxxxxxxxxxxx> 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 <laijs@xxxxxxxxxxxxxx> Cc: Gautham R Shenoy <ego@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/cpu.c | 40 ++++++++++++++++++++++------------------ 1 file changed, 22 insertions(+), 18 deletions(-) diff -puN kernel/cpu.c~cpuhotplug-do-not-need-cpu_hotplug_begin-when-config_hotplug_cpu=n kernel/cpu.c --- a/kernel/cpu.c~cpuhotplug-do-not-need-cpu_hotplug_begin-when-config_hotplug_cpu=n +++ a/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(c */ 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) { _ Patches currently in -mm which might be from laijs@xxxxxxxxxxxxxx are cpuhotplug-do-not-need-cpu_hotplug_begin-when-config_hotplug_cpu=n.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html