oprofile: fix CPU unplug panic in ppro_stop()

If oprofile statically compiled in kernel, a cpu unplug triggers
a panic in ppro_stop(), because a NULL pointer is dereferenced.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
index 716d26f0e5d..e9f80c744cf 100644
--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -156,6 +156,8 @@ static void ppro_start(struct op_msrs const * const msrs)
         unsigned int low, high;
         int i;
 
+        if (!reset_value)
+                return;
         for (i = 0; i < num_counters; ++i) {
                 if (reset_value[i]) {
                         CTRL_READ(low, high, msrs, i);
@@ -171,6 +173,8 @@ static void ppro_stop(struct op_msrs const * const msrs)
         unsigned int low, high;
         int i;
 
+        if (!reset_value)
+                return;
         for (i = 0; i < num_counters; ++i) {
                 if (!reset_value[i])
                         continue;