perf_counter: fix up counter free paths

Impact: fix crash during perfcounters use

I found another counter free path, create a free_counter() call to
accomodate generic tear-down.

Fixes an RCU bug.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.652078652@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 99d5930f0a5259e1f29aaf6778184d540b843489..97f891ffeb40611f0f966dab3087646d76a78a71 100644 (file)
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1150,6 +1150,11 @@ static void free_counter_rcu(struct rcu_head *head)
        kfree(counter);
 }
 
+static void free_counter(struct perf_counter *counter)
+{
+       call_rcu(&counter->rcu_head, free_counter_rcu);
+}
+
 /*
  * Called when the last reference to the file is gone.
  */
@@ -1168,7 +1173,7 @@ static int perf_release(struct inode *inode, struct file *file)
        mutex_unlock(&counter->mutex);
        mutex_unlock(&ctx->mutex);
 
-       call_rcu(&counter->rcu_head, free_counter_rcu);
+       free_counter(counter);
        put_context(ctx);
 
        return 0;
@@ -2128,10 +2133,10 @@ __perf_counter_exit_task(struct task_struct *child,
                                         list_entry) {
                        if (sub->parent) {
                                sync_child_counter(sub, sub->parent);
-                               kfree(sub);
+                               free_counter(sub);
                        }
                }
-               kfree(child_counter);
+               free_counter(child_counter);
        }
 }