oprofile: fix race condition in event_buffer free

[pandora-kernel.git] / drivers / oprofile / event_buffer.c

diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 2b7ae36..c38adb3 100644 (file)
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -41,6 +41,12 @@ static atomic_t buffer_ready = ATOMIC_INIT(0);
  */
 void add_event_entry(unsigned long value)
 {
+       /*
+        * catch potential error
+        */
+       if (!event_buffer)
+               return;
+
        if (buffer_pos == buffer_size) {
                atomic_inc(&oprofile_stats.event_lost_overflow);
                return;
@@ -92,9 +98,10 @@ out:
 
 void free_event_buffer(void)
 {
+       mutex_lock(&buffer_mutex);
        vfree(event_buffer);
-
        event_buffer = NULL;
+       mutex_unlock(&buffer_mutex);
 }
 
 
@@ -167,6 +174,11 @@ static ssize_t event_buffer_read(struct file *file, char __user *buf,
 
        mutex_lock(&buffer_mutex);
 
+       if (!event_buffer) {
+               retval = -EINTR;
+               goto out;
+       }
+
        atomic_set(&buffer_ready, 0);
 
        retval = -EFAULT;