Messages in this thread | | | Date | Wed, 6 Oct 2021 11:15:36 -0600 | From | Mathieu Poirier <> | Subject | Re: [PATCH v2 12/17] coresight: trbe: Add a helper to fetch cpudata from perf handle |
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On Tue, Oct 05, 2021 at 11:35:13PM +0100, Suzuki K Poulose wrote: > Hi Mathieu > > On 04/10/2021 18:42, Mathieu Poirier wrote: > > On Tue, Sep 21, 2021 at 02:41:16PM +0100, Suzuki K Poulose wrote: > > > Add a helper to get the CPU specific data for TRBE instance, from > > > a given perf handle. This also adds extra checks to make sure that > > > the event associated with the handle is "bound" to the CPU and is > > > active on the TRBE. > > > > > > Cc: Anshuman Khandual <anshuman.khandual@arm.com> > > > Cc: Mike Leach <mike.leach@linaro.org> > > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > > > Cc: Leo Yan <leo.yan@linaro.org> > > > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > > > --- > > > drivers/hwtracing/coresight/coresight-trbe.c | 12 ++++++++++-- > > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > > > index 983dd5039e52..797d978f9fa7 100644 > > > --- a/drivers/hwtracing/coresight/coresight-trbe.c > > > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > > > @@ -268,6 +268,15 @@ static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle) > > > return buf->nr_pages * PAGE_SIZE; > > > } > > > +static inline struct trbe_cpudata * > > > +trbe_handle_to_cpudata(struct perf_output_handle *handle) > > > +{ > > > + struct trbe_buf *buf = etm_perf_sink_config(handle); > > > + > > > + BUG_ON(!buf || !buf->cpudata); > > > + return buf->cpudata; > > > +} > > > + > > > /* > > > * TRBE Limit Calculation > > > * > > > @@ -533,8 +542,7 @@ static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *hand > > > { > > > int ec = get_trbe_ec(trbsr); > > > int bsc = get_trbe_bsc(trbsr); > > > - struct trbe_buf *buf = etm_perf_sink_config(handle); > > > - struct trbe_cpudata *cpudata = buf->cpudata; > > > + struct trbe_cpudata *cpudata = trbe_handle_to_cpudata(handle); > > > > There is two other places where this pattern is present: is_perf_trbe() and > > __trbe_normal_offset(). > > I skipped them, as they have to get access to the "trbe_buf" anyways. > So the step by step, made sense. But I could replace them too to make it > transparent. > > What do you think ?
Humm... I don't think there is a right way or a wrong way here. If we move forward with this patchset we have two ways of getting to buf->cpudata. One using trbe_handle_to_cpudata() and another one as laid out in is_perf_trbe() and __trbe_normal_offset(), each with an equal number of occurences (2 for each).
I am usually not fond of small functions like trbe_handle_to_cpudata() and to me keeping the current heuristic in trbe_get_fault_act() would have been just fine. I agree with the argument that trbe_handle_to_cpudata() provides more checks but is it really worth it if they aren't done everywhere?
In short I would get rid of trbe_handle_to_cpudata() entirely and live without the extra checks... But I'm not strongly opinionated on this either.
> > Suzuki > >
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