Re: [PATCH v3 02/13] coresight: etb10: Fix handling of perf mode

Mathieu Poirier
2018-08-01T19:23:24Z

On Tue, 31 Jul 2018 at 15:32, Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
> On 07/31/2018 06:07 PM, Mathieu Poirier wrote:
> > Hello,
> >
> > On Thu, Jul 26, 2018 at 01:54:40PM +0100, Suzuki K Poulose wrote:
> >> If the ETB is already enabled in sysfs mode, the ETB reports
> >> success even if a perf mode is requested. Fix this by checking
> >> the requested mode.
> >>
> >> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> >> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> >> ---
> >> drivers/hwtracing/coresight/coresight-etb10.c | 8 ++++++--
> >> 1 file changed, 6 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
> >> index 306119e..e5808fd 100644
> >> --- a/drivers/hwtracing/coresight/coresight-etb10.c
> >> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> >> @@ -148,8 +148,12 @@ static int etb_enable(struct coresight_device *csdev, u32 mode)
> >> return -EBUSY;
> >>
> >> /* Nothing to do, the tracer is already enabled. */
> >> - if (val == CS_MODE_SYSFS)
> >> - goto out;
> >> + if (val == CS_MODE_SYSFS) {
> >> + if (mode == CS_MODE_SYSFS)
> >> + goto out;
> >> + else
> >> + return -EBUSY;
> >> + }
> >
> > How about:
> >
> > if (val == CS_MODE_PERF)
> > return -EBUSY;
> >
> > + /* Don't let perf disturb sysFS sessions */
> > + if (val == CS_MODE_SYSFS && mode = CS_MODE_PERF)
> > + return -EBUSY;
> > +
> > /* Nothing to do, the tracer is already enabled. */
> > if (val == CS_MODE_SYSFS)
> > goto out;
> >
> >
> > I just find it more readable that way.
>
> Sure, thats fine by me.

Ok good. Doing another round just to address this is cumbersome so I
just fixed it in my tree. Also, I still think the WARN_ON() in patch
5/13 is superfluous but once again not important enough to make a big
deal out of it. I have applied this set.

Thanks,
Mathieu

>
> Cheers
> Suzuki
>