Re: [PATCH v3] coresight: tmc-etr: Fix perf_data check.
From: Mathieu Poirier
Date: Mon Aug 19 2019 - 18:55:41 EST
On Thu, 15 Aug 2019 at 12:46, Yabin Cui <yabinc@xxxxxxxxxx> wrote:
>
> When tracing etm data of multiple threads on multiple cpus through
> perf interface, each cpu has a unique etr_perf_buffer while sharing
> the same etr device. There is no guarantee that the last cpu starts
> etm tracing also stops last. This makes perf_data check fail.
>
> Fix it by checking etr_buf instead of etr_perf_buffer.
> Also move the code setting and clearing perf_buf to more suitable
> places.
>
> Fixes: 3147da92a8a8 ("coresight: tmc-etr: Allocate and free ETR memory buffers for CPU-wide scenarios")
> Signed-off-by: Yabin Cui <yabinc@xxxxxxxxxx>
> ---
>
> v2 -> v3:
> moved place of setting drvdata->perf_buf based on review comment.
> Also moved place of clearing drvdata->perf_buf from
> tmc_update_etr_buffer() to tmc_disable_etr_sink() for below
> situation:
>
> cpu 0 enable etr device (set perf_buf)
> cpu 0 update etr buffer (clear perf_buf)
> cpu 1 enable etr device (perf_buf isn't set because pid set by cpu 0)
> cpu 0 disable etr device
> cpu 1 update etr buffer (perf_buf == NULL, check fails)
>
> To fix it, we need to move clearing perf_buf to the disable function.
>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etr.c | 8 ++++----
> drivers/hwtracing/coresight/coresight-tmc.h | 6 +++---
> 2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 17006705287a..80af313f55d7 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1484,7 +1484,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
> goto out;
> }
>
> - if (WARN_ON(drvdata->perf_data != etr_perf)) {
> + if (WARN_ON(drvdata->perf_buf != etr_buf)) {
> lost = true;
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> goto out;
> @@ -1496,8 +1496,6 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
> tmc_sync_etr_buf(drvdata);
>
> CS_LOCK(drvdata->base);
> - /* Reset perf specific data */
> - drvdata->perf_data = NULL;
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> size = etr_buf->len;
> @@ -1556,7 +1554,6 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
> }
>
> etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);
> - drvdata->perf_data = etr_perf;
>
> /*
> * No HW configuration is needed if the sink is already in
> @@ -1572,6 +1569,7 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
> /* Associate with monitored process. */
> drvdata->pid = pid;
> drvdata->mode = CS_MODE_PERF;
> + drvdata->perf_buf = etr_perf->etr_buf;
> atomic_inc(csdev->refcnt);
> }
>
> @@ -1617,6 +1615,8 @@ static int tmc_disable_etr_sink(struct coresight_device *csdev)
> /* Dissociate from monitored process. */
> drvdata->pid = -1;
> drvdata->mode = CS_MODE_DISABLED;
> + /* Reset perf specific data */
> + drvdata->perf_buf = NULL;
>
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 1ed50411cc3c..f9a0c95e9ba2 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -178,8 +178,8 @@ struct etr_buf {
> * device configuration register (DEVID)
> * @idr: Holds etr_bufs allocated for this ETR.
> * @idr_mutex: Access serialisation for idr.
> - * @perf_data: PERF buffer for ETR.
> - * @sysfs_data: SYSFS buffer for ETR.
> + * @sysfs_buf: SYSFS buffer for ETR.
> + * @perf_buf: PERF buffer for ETR.
> */
> struct tmc_drvdata {
> void __iomem *base;
> @@ -202,7 +202,7 @@ struct tmc_drvdata {
> struct idr idr;
> struct mutex idr_mutex;
> struct etr_buf *sysfs_buf;
> - void *perf_data;
> + struct etr_buf *perf_buf;
> };
I have applied your patch.
Thanks,
Mathieu
>
> struct etr_buf_operations {
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>