linux-kernel - Re: [PATCH v2 3/3] coresight: core: Disable helpers for devices that fail to enable

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Message-ID: <20250402133232.GJ115840@e132581.arm.com>
Date: Wed, 2 Apr 2025 14:32:32 +0100
From: Leo Yan <leo.yan@....com>
To: Yabin Cui <yabinc@...gle.com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	Mike Leach <mike.leach@...aro.org>,
	James Clark <james.clark@...aro.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] coresight: core: Disable helpers for devices that
 fail to enable

On Tue, Apr 01, 2025 at 06:22:46PM -0700, Yabin Cui wrote:
> On Tue, Apr 1, 2025 at 6:19 PM Yabin Cui <yabinc@...gle.com> wrote:
> >
> > When enabling a SINK or LINK type coresight device fails, the
> > associated helpers should be disabled.
> >
> > Signed-off-by: Yabin Cui <yabinc@...gle.com>
> > Suggested-by: Suzuki K Poulose <suzuki.poulose@....com>
> > ---
> >  drivers/hwtracing/coresight/coresight-core.c | 12 ++++--------
> >  1 file changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> > index fb43ef6a3b1f..e3270d9b46c9 100644
> > --- a/drivers/hwtracing/coresight/coresight-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > @@ -465,7 +465,7 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode,
> >                 /* Enable all helpers adjacent to the path first */
> >                 ret = coresight_enable_helpers(csdev, mode, path);
> >                 if (ret)
> > -                       goto err;
> > +                       goto err_helper;
> >                 /*
> >                  * ETF devices are tricky... They can be a link or a sink,
> >                  * depending on how they are configured.  If an ETF has been
> > @@ -480,14 +480,8 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode,
> >                 switch (type) {
> >                 case CORESIGHT_DEV_TYPE_SINK:
> >                         ret = coresight_enable_sink(csdev, mode, sink_data);
> > -                       /*
> > -                        * Sink is the first component turned on. If we
> > -                        * failed to enable the sink, there are no components
> > -                        * that need disabling. Disabling the path here
> > -                        * would mean we could disrupt an existing session.
> > -                        */
> >                         if (ret)
> > -                               goto out;
> > +                               goto err;
> >                         break;
> >                 case CORESIGHT_DEV_TYPE_SOURCE:
> >                         /* sources are enabled from either sysFS or Perf */
> > @@ -507,6 +501,8 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode,
> >  out:
> >         return ret;
> >  err:
> > +       coresight_disable_helpers(csdev);

Given it is unconditionally to enable helpers, I would suggest we
disable helper unconditionally.  Thus, we don't need to add a new
'err_helper' tag, simply reuse the 'err' tag would be fine.

I would like to know if mainatiners have different opinions.

Thanks,
Leo

> > +err_helper:
> >         coresight_disable_path_from(path, nd);
> >         goto out;
> >  }
> > --
> > 2.49.0.472.ge94155a9ec-goog
> >