perf_counter: Sanitize counter->mutex

s/counter->mutex/counter->child_mutex/ and make sure its only
used to protect child_list.

The usage in __perf_counter_exit_task() doesn't appear to be
problematic since ctx->mutex also covers anything related to fd
tear-down.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.533186528@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 4 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 23ddd29730f8..4ab8050eb9e8 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -452,9 +452,6 @@ struct perf_counter {
         struct perf_counter_context     *ctx;
         struct file                     *filp;
 
-        struct perf_counter             *parent;
-        struct list_head                child_list;
-
         /*
          * These accumulate total time (in nanoseconds) that children
          * counters have been enabled and running, respectively.
@@ -465,7 +462,9 @@ struct perf_counter {
         /*
          * Protect attach/detach and child_list:
          */
-        struct mutex                    mutex;
+        struct mutex                    child_mutex;
+        struct list_head                child_list;
+        struct perf_counter             *parent;
 
         int                             oncpu;
         int                             cpu;