cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 3 deletions

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index c3e165c2318f..fd599829e72a 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -726,11 +726,11 @@ static void rcu_torture_shuffle_tasks(void)
         cpumask_t tmp_mask = CPU_MASK_ALL;
         int i;
 
-        lock_cpu_hotplug();
+        get_online_cpus();
 
         /* No point in shuffling if there is only one online CPU (ex: UP) */
         if (num_online_cpus() == 1) {
-                unlock_cpu_hotplug();
+                put_online_cpus();
                 return;
         }
 
@@ -762,7 +762,7 @@ static void rcu_torture_shuffle_tasks(void)
         else
                 rcu_idle_cpu--;
 
-        unlock_cpu_hotplug();
+        put_online_cpus();
 }
 
 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the