[patch V3 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu()

[Thomas Gleixner]

From: Sebastian Andrzej Siewior 

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 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 

---
 kernel/cpu.c |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -701,7 +701,7 @@ 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();

[patch V3 17/32] cpu/hotplug: Use stop_machine_cpuslocked() in takedown_cpu()

[Thomas Gleixner]

From: Sebastian Andrzej Siewior 

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 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 

---
 kernel/cpu.c |2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -701,7 +701,7 @@ 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();