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, 2 insertions, 2 deletions

diff --git a/net/core/flow.c b/net/core/flow.c
index 3ed2b4b1d6d4..6489f4e24ecf 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -293,7 +293,7 @@ void flow_cache_flush(void)
         static DEFINE_MUTEX(flow_flush_sem);
 
         /* Don't want cpus going down or up during this. */
-        lock_cpu_hotplug();
+        get_online_cpus();
         mutex_lock(&flow_flush_sem);
         atomic_set(&info.cpuleft, num_online_cpus());
         init_completion(&info.completion);
@@ -305,7 +305,7 @@ void flow_cache_flush(void)
 
         wait_for_completion(&info.completion);
         mutex_unlock(&flow_flush_sem);
-        unlock_cpu_hotplug();
+        put_online_cpus();
 }
 
 static void __devinit flow_cache_cpu_prepare(int cpu)