oprofile: warn on freeing event buffer too early (c0868934) · Commits · 戴 / test

drivers/oprofile/event_buffer.c

+15 −10

Original line number	Diff line number	Diff line
		@@ -35,17 +35,22 @@ 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)
		{
		/*
		* catch potential error
		* This shouldn't happen since all workqueues or handlers are
		* canceled or flushed before the event buffer is freed.
		*/
		if (!event_buffer)
		if (!event_buffer) {
		WARN_ON_ONCE(1);
		return;
		}

		if (buffer_pos == buffer_size) {
		atomic_inc(&oprofile_stats.event_lost_overflow);
		@@ -75,7 +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);
		@@ -86,13 +90,12 @@ 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;
		}


		@@ -100,6 +103,7 @@ void free_event_buffer(void)
		{
		mutex_lock(&buffer_mutex);
		vfree(event_buffer);
		buffer_pos = 0;
		event_buffer = NULL;
		mutex_unlock(&buffer_mutex);
		}
		@@ -174,6 +178,7 @@ 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;

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