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>
diff --git a/kernel/sched.c b/kernel/sched.c
index 86e55a9..672aa68 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7152,7 +7152,7 @@
int i, cpu, balanced = 1;
/* Prevent cpus going down or coming up */
- lock_cpu_hotplug();
+ get_online_cpus();
/* lockout changes to doms_cur[] array */
lock_doms_cur();
/*
@@ -7186,7 +7186,7 @@
rcu_read_unlock();
unlock_doms_cur();
- unlock_cpu_hotplug();
+ put_online_cpus();
if (!balanced)
timeout = sysctl_sched_min_bal_int_shares;