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[68.147.8.254]) by smtp.gmail.com with ESMTPSA id 77-v6sm3905080pfw.159.2018.09.27.10.07.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Sep 2018 10:07:50 -0700 (PDT) Date: Thu, 27 Sep 2018 11:07:48 -0600 From: Mathieu Poirier To: Alexander Shishkin Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: Re: [QUEUED v20180920 05/16] stm class: Add a helper for writing data packets Message-ID: <20180927170748.GC7481@xps15> References: <20180920124553.56978-1-alexander.shishkin@linux.intel.com> <20180920124553.56978-6-alexander.shishkin@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180920124553.56978-6-alexander.shishkin@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 20, 2018 at 03:45:42PM +0300, Alexander Shishkin wrote: > Add a helper to write a sequence of bytes as STP data packets. This > is used by protocol drivers to output their metadata, as well as the > actual data payload. > > Signed-off-by: Alexander Shishkin > --- > drivers/hwtracing/stm/core.c | 50 ++++++++++++++++++++++++++---------- > drivers/hwtracing/stm/stm.h | 3 +++ > 2 files changed, 40 insertions(+), 13 deletions(-) > > diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c > index c869a30661ac..9ed2f06deb47 100644 > --- a/drivers/hwtracing/stm/core.c > +++ b/drivers/hwtracing/stm/core.c > @@ -564,27 +564,51 @@ stm_assign_first_policy(struct stm_device *stm, struct stm_output *output, > return err; > } > > -static ssize_t notrace stm_write(struct stm_data *data, unsigned int master, > - unsigned int channel, const char *buf, size_t count) > +/** > + * stm_data_write() - send the given payload as data packets > + * @data: stm driver's data > + * @m: STP master > + * @c: STP channel > + * @ts_first: timestamp the first packet > + * @buf: data payload buffer > + * @count: data payload size > + */ > +ssize_t notrace stm_data_write(struct stm_data *data, unsigned int m, > + unsigned int c, bool ts_first, const void *buf, > + size_t count) > { > - unsigned int flags = STP_PACKET_TIMESTAMPED; > - const unsigned char *p = buf, nil = 0; > - size_t pos; > + unsigned int flags = ts_first ? STP_PACKET_TIMESTAMPED : 0; > ssize_t sz; > + size_t pos; > > - for (pos = 0, p = buf; count > pos; pos += sz, p += sz) { > + for (pos = 0, sz = 0; pos < count; pos += sz) { > sz = min_t(unsigned int, count - pos, 8); > - sz = data->packet(data, master, channel, STP_PACKET_DATA, flags, > - sz, p); > - flags = 0; > - > - if (sz < 0) > + sz = data->packet(data, m, c, STP_PACKET_DATA, flags, sz, > + &((u8 *)buf)[pos]); > + if (sz <= 0) > break; > + > + if (ts_first) { > + flags = 0; > + ts_first = false; > + } > } > > - data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil); > + return sz < 0 ? sz : pos; > +} > +EXPORT_SYMBOL_GPL(stm_data_write); > + > +static ssize_t notrace stm_write(struct stm_data *data, unsigned int master, > + unsigned int channel, const char *buf, size_t count) > +{ > + ssize_t sz; > + > + sz = stm_data_write(data, master, channel, true, buf, count); > + if (sz > 0) > + data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, > + buf); The original code the payload of a flag packet was '0' while in this patch changes it to be anything. Some external tooling could be very confused. > > - return pos; > + return sz; > } > > static ssize_t stm_char_write(struct file *file, const char __user *buf, > diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h > index 921ebd9fd3bd..753d83acb7ae 100644 > --- a/drivers/hwtracing/stm/stm.h > +++ b/drivers/hwtracing/stm/stm.h > @@ -111,5 +111,8 @@ int stm_lookup_protocol(const char *name, > const struct stm_protocol_driver **pdrv, > const struct config_item_type **type); > void stm_put_protocol(const struct stm_protocol_driver *pdrv); > +ssize_t stm_data_write(struct stm_data *data, unsigned int m, > + unsigned int c, bool ts_first, const void *buf, > + size_t count); > > #endif /* _STM_STM_H_ */ > -- > 2.18.0 >