On Wed, 2013-07-03 at 00:23 +0200, Oleg Nesterov wrote:
> On 07/02, Oleg Nesterov wrote:
> >
> > So please ignore modules ;)
>
> Or lets discuss the change above.
I like this better than your first change, as the module code really
can't fail to remove events, as that will complicate things more than
they already are ;-)
>
> Oleg.
>
> --- x/kernel/trace/trace_events.c
> +++ x/kernel/trace/trace_events.c
> @@ -1611,14 +1611,40 @@ static void __trace_remove_event_call(st
> destroy_preds(call);
> }
>
> +static int event_can_remove(struct ftrace_event_call *call)
Should rename this to "event_is_busy" as we are only seeing if the event
is active or not, as we do allow for events to be removed when active.
This may confuse new reviewers.
> +{
> + 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;
> + if (file->flags & FTRACE_EVENT_FL_ENABLED)
> + return -EBUSY;
> + break;
> + } while_for_each_event_file();
> +
> + 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)
Probably should rename this to trace_probe_remove_event_call() as this
deals only with the probe callers (kprobe and uprobe). Also this code
will need to be documented a bit more.
Other than that, sure, go with it. Masami, you have any comments?
-- Steve
> {
> + int err;
> +
> mutex_lock(&event_mutex);
> down_write(&trace_event_sem);
> - __trace_remove_event_call(call);
> + err = event_can_remove(call);
> + if (!err)
> + __trace_remove_event_call(call);
> up_write(&trace_event_sem);
> mutex_unlock(&event_mutex);
> +
> + return err;
> }
>
> #define for_each_event(event, start, end) \
--
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