diff options
| -rw-r--r-- | drivers/oprofile/event_buffer.c | 35 |
1 files changed, 26 insertions, 9 deletions
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c index 2b7ae366ceb..5df60a6b677 100644 --- a/drivers/oprofile/event_buffer.c +++ b/drivers/oprofile/event_buffer.c @@ -35,12 +35,23 @@ static size_t buffer_pos; /* atomic_t because wait_event checks it outside of buffer_mutex */ static atomic_t buffer_ready = ATOMIC_INIT(0); -/* Add an entry to the event buffer. When we - * get near to the end we wake up the process - * sleeping on the read() of the file. +/* + * Add an entry to the event buffer. When we get near to the end we + * wake up the process sleeping on the read() of the file. To protect + * the event_buffer this function may only be called when buffer_mutex + * is set. */ void add_event_entry(unsigned long value) { + /* + * This shouldn't happen since all workqueues or handlers are + * canceled or flushed before the event buffer is freed. + */ + if (!event_buffer) { + WARN_ON_ONCE(1); + return; + } + if (buffer_pos == buffer_size) { atomic_inc(&oprofile_stats.event_lost_overflow); return; @@ -69,7 +80,6 @@ void wake_up_buffer_waiter(void) int alloc_event_buffer(void) { - int err = -ENOMEM; unsigned long flags; spin_lock_irqsave(&oprofilefs_lock, flags); @@ -80,21 +90,22 @@ int alloc_event_buffer(void) if (buffer_watershed >= buffer_size) return -EINVAL; + buffer_pos = 0; event_buffer = vmalloc(sizeof(unsigned long) * buffer_size); if (!event_buffer) - goto out; + return -ENOMEM; - err = 0; -out: - return err; + return 0; } void free_event_buffer(void) { + mutex_lock(&buffer_mutex); vfree(event_buffer); - + buffer_pos = 0; event_buffer = NULL; + mutex_unlock(&buffer_mutex); } @@ -167,6 +178,12 @@ static ssize_t event_buffer_read(struct file *file, char __user *buf, mutex_lock(&buffer_mutex); + /* May happen if the buffer is freed during pending reads. */ + if (!event_buffer) { + retval = -EINTR; + goto out; + } + atomic_set(&buffer_ready, 0); retval = -EFAULT; |