diff options
author | Oleg Nesterov <oleg@redhat.com> | 2015-10-09 18:00:49 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2015-10-20 10:23:55 +0200 |
commit | c00166d87e730088d919814020e96ffed129d0d1 (patch) | |
tree | 89194ca8d10e2c6ceddf203958e65787927d9f9b | |
parent | d8bc853582bfd81a9c08ca6922aeb01570080ccc (diff) | |
download | lwn-c00166d87e730088d919814020e96ffed129d0d1.tar.gz lwn-c00166d87e730088d919814020e96ffed129d0d1.zip |
stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
1. Change smpboot_unpark_thread() to check ->selfparking, just
like smpboot_park_thread() does.
2. Introduce stop_machine_unpark() which sets ->enabled and calls
kthread_unpark().
3. Change smpboot_thread_call() and cpu_stop_init() to call
stop_machine_unpark() by hand.
This way:
- IMO the ->selfparking logic becomes more consistent.
- We can kill the smp_hotplug_thread->pre_unpark() method.
- We can easily unpark the stopper thread earlier. Say, we
can move stop_machine_unpark() from smpboot_thread_call()
to sched_cpu_active() as Peter suggests.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: heiko.carstens@de.ibm.com
Link: http://lkml.kernel.org/r/20151009160049.GA10166@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r-- | include/linux/smpboot.h | 4 | ||||
-rw-r--r-- | include/linux/stop_machine.h | 1 | ||||
-rw-r--r-- | kernel/cpu.c | 1 | ||||
-rw-r--r-- | kernel/smpboot.c | 5 | ||||
-rw-r--r-- | kernel/stop_machine.c | 10 |
5 files changed, 13 insertions, 8 deletions
diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h index e6109a6cd8f6..12910cf19869 100644 --- a/include/linux/smpboot.h +++ b/include/linux/smpboot.h @@ -24,9 +24,6 @@ struct smpboot_thread_data; * parked (cpu offline) * @unpark: Optional unpark function, called when the thread is * unparked (cpu online) - * @pre_unpark: Optional unpark function, called before the thread is - * unparked (cpu online). This is not guaranteed to be - * called on the target cpu of the thread. Careful! * @cpumask: Internal state. To update which threads are unparked, * call smpboot_update_cpumask_percpu_thread(). * @selfparking: Thread is not parked by the park function. @@ -42,7 +39,6 @@ struct smp_hotplug_thread { void (*cleanup)(unsigned int cpu, bool online); void (*park)(unsigned int cpu); void (*unpark)(unsigned int cpu); - void (*pre_unpark)(unsigned int cpu); cpumask_var_t cpumask; bool selfparking; const char *thread_comm; diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h index 7b76362b381c..0adedca24c5b 100644 --- a/include/linux/stop_machine.h +++ b/include/linux/stop_machine.h @@ -34,6 +34,7 @@ void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg); void stop_machine_park(int cpu); +void stop_machine_unpark(int cpu); #else /* CONFIG_SMP */ diff --git a/kernel/cpu.c b/kernel/cpu.c index c85df2775b73..6467521e1e15 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -475,6 +475,7 @@ static int smpboot_thread_call(struct notifier_block *nfb, case CPU_DOWN_FAILED: case CPU_ONLINE: + stop_machine_unpark(cpu); smpboot_unpark_threads(cpu); break; diff --git a/kernel/smpboot.c b/kernel/smpboot.c index a818cbc73e14..d264f59bff56 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -222,9 +222,8 @@ static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cp { struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu); - if (ht->pre_unpark) - ht->pre_unpark(cpu); - kthread_unpark(tsk); + if (!ht->selfparking) + kthread_unpark(tsk); } void smpboot_unpark_threads(unsigned int cpu) diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 91fbb109de6c..59096a55089f 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -513,6 +513,14 @@ static void cpu_stop_unpark(unsigned int cpu) spin_unlock_irq(&stopper->lock); } +void stop_machine_unpark(int cpu) +{ + struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); + + cpu_stop_unpark(cpu); + kthread_unpark(stopper->thread); +} + static struct smp_hotplug_thread cpu_stop_threads = { .store = &cpu_stopper.thread, .thread_should_run = cpu_stop_should_run, @@ -521,7 +529,6 @@ static struct smp_hotplug_thread cpu_stop_threads = { .create = cpu_stop_create, .setup = cpu_stop_unpark, .park = cpu_stop_park, - .pre_unpark = cpu_stop_unpark, .selfparking = true, }; @@ -537,6 +544,7 @@ static int __init cpu_stop_init(void) } BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads)); + stop_machine_unpark(raw_smp_processor_id()); stop_machine_initialized = true; return 0; } |