| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Wed, 24 May 2017 10:15:28 +0200 |
| Subject: [PATCH 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in |
| takedown_cpu() |
| |
| takedown_cpu() is a cpu hotplug function invoking stop_machine(). The cpu |
| hotplug machinery holds the hotplug lock for write. |
| |
| stop_machine() invokes get_online_cpus() as well. This is correct, but |
| prevents the conversion of the hotplug locking to a percpu rwsem. |
| |
| Use stop_machine_cpuslocked() to avoid the nested call. |
| |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
| Acked-by: Ingo Molnar <mingo@kernel.org> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Steven Rostedt <rostedt@goodmis.org> |
| Link: http://lkml.kernel.org/r/20170524081548.423292433@linutronix.de |
| --- |
| kernel/cpu.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/kernel/cpu.c |
| +++ b/kernel/cpu.c |
| @@ -711,7 +711,7 @@ static int takedown_cpu(unsigned int cpu |
| /* |
| * So now all preempt/rcu users must observe !cpu_active(). |
| */ |
| - err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu)); |
| + err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu)); |
| if (err) { |
| /* CPU refused to die */ |
| irq_unlock_sparse(); |