Re: [PATCH v3 05/10] coresight: trbe: Drop duplicate TRUNCATE flags

From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
	coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
	mike.leach@linaro.org, leo.yan@linaro.org, tamas.zsoldos@arm.com,
	jinlmao@qti.qualcomm.com, al.grant@arm.com, denik@google.com
Subject: Re: [PATCH v3 05/10] coresight: trbe: Drop duplicate TRUNCATE flags
Date: Wed, 22 Sep 2021 10:34:36 -0600	[thread overview]
Message-ID: <20210922163436.GB2129167@p14s> (raw)
In-Reply-To: <47f5a2cd-c435-7804-c3ff-06b8d266ee9b@arm.com>

On Wed, Sep 15, 2021 at 10:56:17AM +0530, Anshuman Khandual wrote:
> 
> 
> On 9/14/21 3:56 PM, Suzuki K Poulose wrote:
> > We mark the buffer as TRUNCATED when there is no space left
> > in the buffer. But we do it at different points.
> >     __trbe_normal_offset()
> > and also, at all the callers of the above function via
> > compute_trbe_buffer_limit(), when the limit == base (i.e
> > offset = 0 as returned by the __trbe_normal_offset()).
> > 
> > So, given that the callers already mark the buffer as TRUNCATED
> > drop the caller inside the __trbe_normal_offset().
> > 
> > This is in preparation to moving the handling of TRUNCATED
> > into a central place.
> > 
> > Cc: Anshuman Khandual <anshuman.khandual@arm.com>
> > Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> > Cc: Mike Leach <mike.leach@linaro.org>
> > Cc: Leo Yan <leo.yan@linaro.org>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> 
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
> 
> A small nit though.
> 
> > ---
> > Change since v2:
> >   - Added the flag for trbe_handle_spurious() -  Anshuman
> > ---
> >  drivers/hwtracing/coresight/coresight-trbe.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> > index 81bf183a73a1..5297b11f26b7 100644
> > --- a/drivers/hwtracing/coresight/coresight-trbe.c
> > +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> > @@ -252,13 +252,9 @@ static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
> >  	 * trbe_base				trbe_base + nr_pages
> >  	 *
> >  	 * Perf aux buffer does not have any space for the driver to write into.
> > -	 * Just communicate trace truncation event to the user space by marking
> > -	 * it with PERF_AUX_FLAG_TRUNCATED.
> 
> Should not this comment be moved, where PERF_AUX_FLAG_TRUNCATED
> gets marked after this change ?

I moved the comment and applied this patch.

> 
> >  	 */
> > -	if (!handle->size) {
> > -		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> > +	if (!handle->size)
> >  		return 0;
> > -	}
> >  
> >  	/* Compute the tail and wakeup indices now that we've aligned head */
> >  	tail = PERF_IDX2OFF(handle->head + handle->size, buf);
> > @@ -360,7 +356,6 @@ static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
> >  		return limit;
> >  
> >  	trbe_pad_buf(handle, handle->size);
> > -	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> >  	return 0;
> >  }
> >  
> > @@ -688,6 +683,7 @@ static void trbe_handle_spurious(struct perf_output_handle *handle)
> >  	buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf);
> >  	if (buf->trbe_limit == buf->trbe_base) {
> >  		trbe_drain_and_disable_local();
> > +		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
> >  		return;
> >  	}
> >  	trbe_enable_hw(buf);
> > 

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