percpu_counter: use this_cpu_ptr() instead of per_cpu_ptr()

this_cpu_ptr() avoids an array lookup and can use the percpu offset of the
local cpu directly.

Signed-off-by: Christoph Lameter <cl@linux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 1d954ea72331..604678d7d06d 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -73,9 +73,9 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
 {
         s64 count;
         s32 *pcount;
-        int cpu = get_cpu();
 
-        pcount = per_cpu_ptr(fbc->counters, cpu);
+        preempt_disable();
+        pcount = this_cpu_ptr(fbc->counters);
         count = *pcount + amount;
         if (count >= batch || count <= -batch) {
                 spin_lock(&fbc->lock);
@@ -85,7 +85,7 @@ void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
         } else {
                 *pcount = count;
         }
-        put_cpu();
+        preempt_enable();
 }
 EXPORT_SYMBOL(__percpu_counter_add);