| Message ID | 20240429152207.479221-10-james.clark@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | coresight: Use per-sink trace ID maps for Perf sessions | expand |
On Mon, 29 Apr 2024 at 16:24, James Clark <james.clark@arm.com> wrote: > > "Process being monitored" and "pid of the process to monitor" imply that > this would be the same PID if there were two sessions targeting the same > process. But this is actually the PID of the process that did the Perf > event open call, rather than the target of the session. So update the > comments to make this clearer. > > Signed-off-by: James Clark <james.clark@arm.com> > --- > drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++-- > drivers/hwtracing/coresight/coresight-tmc.h | 5 +++-- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c > index e75428fa1592..8962fc27d04f 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c > @@ -36,7 +36,8 @@ struct etr_buf_hw { > * etr_perf_buffer - Perf buffer used for ETR > * @drvdata - The ETR drvdaga this buffer has been allocated for. > * @etr_buf - Actual buffer used by the ETR > - * @pid - The PID this etr_perf_buffer belongs to. > + * @pid - The PID of the session owner that etr_perf_buffer > + * belongs to. > * @snaphost - Perf session mode > * @nr_pages - Number of pages in the ring buffer. > * @pages - Array of Pages in the ring buffer. > @@ -1662,7 +1663,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) > goto unlock_out; > } > > - /* Get a handle on the pid of the process to monitor */ > + /* Get a handle on the pid of the session owner */ > pid = etr_perf->pid; > > /* Do not proceed if this device is associated with another session */ > diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h > index c77763b49de0..2671926be62a 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc.h > +++ b/drivers/hwtracing/coresight/coresight-tmc.h > @@ -171,8 +171,9 @@ struct etr_buf { > * @csdev: component vitals needed by the framework. > * @miscdev: specifics to handle "/dev/xyz.tmc" entry. > * @spinlock: only one at a time pls. > - * @pid: Process ID of the process being monitored by the session > - * that is using this component. > + * @pid: Process ID of the process that owns the session that is using > + * this component. For example this would be the pid of the Perf > + * process. > * @buf: Snapshot of the trace data for ETF/ETB. > * @etr_buf: details of buffer used in TMC-ETR > * @len: size of the available trace for ETF/ETB. > -- > 2.34.1 > Reviewed-by: Mike Leach <mike.leach@linaro.org>
On 4/29/24 20:51, James Clark wrote: > "Process being monitored" and "pid of the process to monitor" imply that > this would be the same PID if there were two sessions targeting the same > process. But this is actually the PID of the process that did the Perf > event open call, rather than the target of the session. So update the > comments to make this clearer. > > Signed-off-by: James Clark <james.clark@arm.com> This indeed removes the ambiguity that the PID belongs to the perf session owner rather than the monitored or target process. Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++-- > drivers/hwtracing/coresight/coresight-tmc.h | 5 +++-- > 2 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c > index e75428fa1592..8962fc27d04f 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c > @@ -36,7 +36,8 @@ struct etr_buf_hw { > * etr_perf_buffer - Perf buffer used for ETR > * @drvdata - The ETR drvdaga this buffer has been allocated for. > * @etr_buf - Actual buffer used by the ETR > - * @pid - The PID this etr_perf_buffer belongs to. > + * @pid - The PID of the session owner that etr_perf_buffer > + * belongs to. > * @snaphost - Perf session mode > * @nr_pages - Number of pages in the ring buffer. > * @pages - Array of Pages in the ring buffer. > @@ -1662,7 +1663,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) > goto unlock_out; > } > > - /* Get a handle on the pid of the process to monitor */ > + /* Get a handle on the pid of the session owner */ > pid = etr_perf->pid; > > /* Do not proceed if this device is associated with another session */ > diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h > index c77763b49de0..2671926be62a 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc.h > +++ b/drivers/hwtracing/coresight/coresight-tmc.h > @@ -171,8 +171,9 @@ struct etr_buf { > * @csdev: component vitals needed by the framework. > * @miscdev: specifics to handle "/dev/xyz.tmc" entry. > * @spinlock: only one at a time pls. > - * @pid: Process ID of the process being monitored by the session > - * that is using this component. > + * @pid: Process ID of the process that owns the session that is using > + * this component. For example this would be the pid of the Perf > + * process. > * @buf: Snapshot of the trace data for ETF/ETB. > * @etr_buf: details of buffer used in TMC-ETR > * @len: size of the available trace for ETF/ETB.
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index e75428fa1592..8962fc27d04f 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -36,7 +36,8 @@ struct etr_buf_hw { * etr_perf_buffer - Perf buffer used for ETR * @drvdata - The ETR drvdaga this buffer has been allocated for. * @etr_buf - Actual buffer used by the ETR - * @pid - The PID this etr_perf_buffer belongs to. + * @pid - The PID of the session owner that etr_perf_buffer + * belongs to. * @snaphost - Perf session mode * @nr_pages - Number of pages in the ring buffer. * @pages - Array of Pages in the ring buffer. @@ -1662,7 +1663,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data) goto unlock_out; } - /* Get a handle on the pid of the process to monitor */ + /* Get a handle on the pid of the session owner */ pid = etr_perf->pid; /* Do not proceed if this device is associated with another session */ diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h index c77763b49de0..2671926be62a 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -171,8 +171,9 @@ struct etr_buf { * @csdev: component vitals needed by the framework. * @miscdev: specifics to handle "/dev/xyz.tmc" entry. * @spinlock: only one at a time pls. - * @pid: Process ID of the process being monitored by the session - * that is using this component. + * @pid: Process ID of the process that owns the session that is using + * this component. For example this would be the pid of the Perf + * process. * @buf: Snapshot of the trace data for ETF/ETB. * @etr_buf: details of buffer used in TMC-ETR * @len: size of the available trace for ETF/ETB.
"Process being monitored" and "pid of the process to monitor" imply that this would be the same PID if there were two sessions targeting the same process. But this is actually the PID of the process that did the Perf event open call, rather than the target of the session. So update the comments to make this clearer. Signed-off-by: James Clark <james.clark@arm.com> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++-- drivers/hwtracing/coresight/coresight-tmc.h | 5 +++-- 2 files changed, 6 insertions(+), 4 deletions(-)