Re: [PATCH v2 1/1] tracing: trace_remove_event_call() should failif call/file is in use

[Steven Rostedt]

On Mon, 2013-07-29 at 19:50 +0200, Oleg Nesterov wrote:
>  
> +static int probe_remove_event_call(struct ftrace_event_call *call)
> +{
> +	struct trace_array *tr;
> +	struct ftrace_event_file *file;
> +
> +#ifdef CONFIG_PERF_EVENTS
> +	if (call->perf_refcount)
> +		return -EBUSY;
> +#endif
> +	do_for_each_event_file(tr, file) {
> +		if (file->event_call != call)
> +			continue;
> +		/*
> +		 * We can't rely on ftrace_event_enable_disable(enable => 0)
> +		 * we are going to do, FTRACE_EVENT_FL_SOFT_MODE can suppress
> +		 * TRACE_REG_UNREGISTER.
> +		 */
> +		if (file->flags & FTRACE_EVENT_FL_ENABLED)
> +			return -EBUSY;
> +		break;

I'm going to modify the patch to include a comment here about the break
being used to go to the next trace_array and not leaving the loop.

-- Steve

> +	} while_for_each_event_file();
> +
> +	__trace_remove_event_call(call);
> +
> +	return 0;
> +}
> +
>  /* Remove an event_call */
> -void trace_remove_event_call(struct ftrace_event_call *call)
> +int trace_remove_event_call(struct ftrace_event_call *call)
>  {
> +	int ret;
> +
>  	mutex_lock(&trace_types_lock);
>  	mutex_lock(&event_mutex);
>  	down_write(&trace_event_sem);
> -	__trace_remove_event_call(call);
> +	ret = probe_remove_event_call(call);
>  	up_write(&trace_event_sem);
>  	mutex_unlock(&event_mutex);
>  	mutex_unlock(&trace_types_lock);
> +
> +	return ret;
>  }
>  
>  #define for_each_event(event, start, end)			\


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