linux-kernel - Re: [PATCH v2 1/3] coresight: catu: Introduce refcount and spinlock for enabling/disabling

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Message-ID: <20250402130145.GI115840@e132581.arm.com>
Date: Wed, 2 Apr 2025 14:01:45 +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 1/3] coresight: catu: Introduce refcount and spinlock
 for enabling/disabling

Hi Yabin,

On Tue, Apr 01, 2025 at 06:21:59PM -0700, Yabin Cui wrote:

[...]

> > @@ -486,12 +491,17 @@ static int catu_disable_hw(struct catu_drvdata *drvdata)
> >
> >  static int catu_disable(struct coresight_device *csdev, void *__unused)
> >  {
> > -       int rc;
> > +       int rc = 0;
> >         struct catu_drvdata *catu_drvdata = csdev_to_catu_drvdata(csdev);
> > +       guard(raw_spinlock_irqsave)(&catu_drvdata->spinlock);
> >
> > -       CS_UNLOCK(catu_drvdata->base);
> > -       rc = catu_disable_hw(catu_drvdata);
> > -       CS_LOCK(catu_drvdata->base);
> > +       if (--csdev->refcnt == 0) {
> > +               CS_UNLOCK(catu_drvdata->base);
> > +               rc = catu_disable_hw(catu_drvdata);
> > +               CS_LOCK(catu_drvdata->base);
> > +       } else {
> > +               rc = -EBUSY;

This is not an error if the decremented reference counter is not zero.
It should return 0.  Otherwise, the change looks good to me.

Thanks,
Leo