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Subject[PATCH 3/4] smpboot: Allow to pass the cpumask on per-cpu thread registration
Date
It makes the registration cheaper and simpler for the smpboot per-cpu
kthread users that don't need to always update the cpumask after threads
creation.

Reviewed-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
include/linux/smpboot.h | 11 ++++++++++-
kernel/smpboot.c | 12 ++++++++----
kernel/watchdog.c | 9 +++------
3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h
index da3c593..e6109a6 100644
--- a/include/linux/smpboot.h
+++ b/include/linux/smpboot.h
@@ -48,7 +48,16 @@ struct smp_hotplug_thread {
const char *thread_comm;
};

-int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread);
+int smpboot_register_percpu_thread_cpumask(struct smp_hotplug_thread *plug_thread,
+ const struct cpumask *cpumask);
+
+static inline int
+smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
+{
+ return smpboot_register_percpu_thread_cpumask(plug_thread,
+ cpu_possible_mask);
+}
+
void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread);
int smpboot_update_cpumask_percpu_thread(struct smp_hotplug_thread *plug_thread,
const struct cpumask *);
diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index 60aa858..d99a41d 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -273,19 +273,22 @@ static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
}

/**
- * smpboot_register_percpu_thread - Register a per_cpu thread related to hotplug
+ * smpboot_register_percpu_thread_cpumask - Register a per_cpu thread related
+ * to hotplug
* @plug_thread: Hotplug thread descriptor
+ * @cpumask: The cpumask where threads run
*
* Creates and starts the threads on all online cpus.
*/
-int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
+int smpboot_register_percpu_thread_cpumask(struct smp_hotplug_thread *plug_thread,
+ const struct cpumask *cpumask)
{
unsigned int cpu;
int ret = 0;

if (!alloc_cpumask_var(&plug_thread->cpumask, GFP_KERNEL))
return -ENOMEM;
- cpumask_copy(plug_thread->cpumask, cpu_possible_mask);
+ cpumask_copy(plug_thread->cpumask, cpumask);

get_online_cpus();
mutex_lock(&smpboot_threads_lock);
@@ -296,7 +299,8 @@ int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
free_cpumask_var(plug_thread->cpumask);
goto out;
}
- smpboot_unpark_thread(plug_thread, cpu);
+ if (cpumask_test_cpu(cpu, cpumask))
+ smpboot_unpark_thread(plug_thread, cpu);
}
list_add(&plug_thread->list, &hotplug_threads);
out:
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index a6ffa43..e5bb86f 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -713,15 +713,12 @@ static int watchdog_enable_all_cpus(void)
int err = 0;

if (!watchdog_running) {
- err = smpboot_register_percpu_thread(&watchdog_threads);
+ err = smpboot_register_percpu_thread_cpumask(&watchdog_threads,
+ &watchdog_cpumask);
if (err)
pr_err("Failed to create watchdog threads, disabled\n");
- else {
- if (smpboot_update_cpumask_percpu_thread(
- &watchdog_threads, &watchdog_cpumask))
- pr_err("Failed to set cpumask for watchdog threads\n");
+ else
watchdog_running = 1;
- }
} else {
/*
* Enable/disable the lockup detectors or
--
2.1.4


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