Messages in this thread | | | Subject | Re: [PATCH 02/17] coresight tmc: Hide trace buffer handling for file read | From | Julien Thierry <> | Date | Fri, 20 Oct 2017 13:34:25 +0100 |
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Hi Suzuki,
On 19/10/17 18:15, Suzuki K Poulose wrote: > At the moment we adjust the buffer pointers for reading the trace > data via misc device in the common code for ETF/ETB and ETR. Since > we are going to change how we manage the buffer for ETR, let us > move the buffer manipulation to the respective driver files, hiding > it from the common code. We do so by adding type specific helpers > for finding the length of data and the pointer to the buffer, > for a given length at a file position. > > Cc: Mathieu Poirier <mathieu.poirier@linaro.org> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > --- > drivers/hwtracing/coresight/coresight-tmc-etf.c | 16 ++++++++++++ > drivers/hwtracing/coresight/coresight-tmc-etr.c | 33 ++++++++++++++++++++++++ > drivers/hwtracing/coresight/coresight-tmc.c | 34 ++++++++++++++----------- > drivers/hwtracing/coresight/coresight-tmc.h | 4 +++ > 4 files changed, 72 insertions(+), 15 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c > index e2513b786242..0b6f1eb746de 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c > @@ -120,6 +120,22 @@ static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata) > CS_LOCK(drvdata->base); > } > > +/* > + * Return the available trace data in the buffer from @pos, with > + * a maximum limit of @len, updating the @bufpp on where to > + * find it. > + */ > +ssize_t tmc_etb_get_sysfs_trace(struct tmc_drvdata *drvdata, > + loff_t pos, size_t len, char **bufpp) > +{ > + /* Adjust the len to available size @pos */ > + if (pos + len > drvdata->len) > + len = drvdata->len - pos; > + if (len > 0)
Do we have some guarantee that "pos <= drvdata->len"? because since len is unsigned this check only covers the case were len is 0.
Maybe it would be better to use a signed variable to store the result of the difference.
> + *bufpp = drvdata->buf + pos; > + return len; > +} > + > static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev) > { > int ret = 0; > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c > index d0208f01afd9..063f253f1c99 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c > @@ -69,6 +69,39 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata) > CS_LOCK(drvdata->base); > } > > +/* > + * Return the available trace data in the buffer @pos, with a maximum > + * limit of @len, also updating the @bufpp on where to find it. > + */ > +ssize_t tmc_etr_get_sysfs_trace(struct tmc_drvdata *drvdata, > + loff_t pos, size_t len, char **bufpp) > +{ > + char *bufp = drvdata->buf + pos; > + char *bufend = (char *)(drvdata->vaddr + drvdata->size); > + > + /* Adjust the len to available size @pos */ > + if (pos + len > drvdata->len) > + len = drvdata->len - pos; > + > + if (len <= 0) > + return len;
Similar issue here.
Cheers,
-- Julien Thierry
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