Re: [PATCH RFC v6 4/5] tracepoint: Make rcuidle tracepoint callers use SRCU
From: Mathieu Desnoyers
Date: Mon May 07 2018 - 20:38:01 EST
----- On May 7, 2018, at 5:46 PM, Joel Fernandes, Google joel@xxxxxxxxxxxxxxxxx wrote:
> On Mon, May 07, 2018 at 05:05:41PM -0400, Mathieu Desnoyers wrote:
>> ----- On May 7, 2018, at 4:41 PM, Joel Fernandes joelaf@xxxxxxxxxx wrote:
>> [...]
>> > +extern struct srcu_struct tracepoint_srcu;
>> > +
>> > extern int
>> > tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data);
>> > extern int
>> > @@ -77,6 +80,9 @@ int unregister_tracepoint_module_notifier(struct
>> > notifier_block *nb)
>> > */
>> > static inline void tracepoint_synchronize_unregister(void)
>> > {
>> > +#ifdef CONFIG_TRACEPOINTS
>> > + synchronize_srcu(&tracepoint_srcu);
>> > +#endif
>> > synchronize_sched();
>>
>> Why is this ifdef needed ?
>
> tracepoint_srcu is defined in tracepoint.c so if we don't protect usage here, it
> would cause a build error.
Then we should ifdef the entire implementation of tracepoint_synchronize_unregister().
There is no point in issuing synchronize_sched() when code invokes that
function on a CONFIG_TRACEPOINTS=n config.
Thanks,
Mathieu
>
> thanks,
>
> - Joel
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com