Re: [PATCH] coresight: etm4x: Fix PID tracing when perf is run in an init PID namespace

[Julien Meunier]

On 08/10/2024 11:59, Suzuki K Poulose wrote:
> On 08/10/2024 07:52, Leo Yan wrote:
> > On 10/7/2024 9:05 PM, Leo Yan wrote:
[...]
> > I thought again and found I was wrong with above conclusion. This 
> > patch is a
> > good fixing for the perf running in root namespace to profile programs in
> > non-root namespace. Sorry for noise.
> >
> > Maybe it is good to improve a bit comments to avoid confusion. See below.
> >
> > [...]
> >
> > > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/ 
> > > > drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > > index bf01f01964cf..8365307b1aec 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > > > @@ -695,7 +695,7 @@ static int etm4_parse_event_config(struct 
> > > > coresight_device *csdev,
> > > >
> > > >        /* Only trace contextID when runs in root PID namespace */
> >
> > We can claim the requirement for the *tool* running in root PID namespae.
> >
> >    /* Only trace contextID when the tool runs in root PID namespace */
>
> minor nit: I wouldn't call "tool". Let keep it "event owner".
>
>         /* Only trace contextID when the event owner is in root PID 
> namespace */
>
>
> Julien,
>
> Please could you respin the patch with the comments addressed.

Sure, I will send a v2 with comments updated.

> Kind regards
> Suzuki
>
>
> > > >        if ((attr->config & BIT(ETM_OPT_CTXTID)) &&
> > > > -         task_is_in_init_pid_ns(current))
> > > > +         task_is_in_init_pid_ns(event->owner))
> > > >                /* bit[6], Context ID tracing bit */
> > > >                config->cfg |= TRCCONFIGR_CID;
> > > >
> > > > @@ -710,7 +710,7 @@ static int etm4_parse_event_config(struct 
> > > > coresight_device *csdev,
> > > >                        goto out;
> > > >                }
> > > >                /* Only trace virtual contextID when runs in root PID 
> > > > namespace */
> >
> > Ditto.
> >
> >    /* Only trace virtual contextID when the tool runs in root PID 
> > namespace */
> >
> > With above change:
> >
> > Reviewed-by: Leo Yan <leo.yan@xxxxxxx>

Regards,
Julien