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SubjectRe: [PATCH V3 13/18] coresight: tmc: make sysFS and Perf mode mutually exclusive
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On 22/04/16 18:14, Mathieu Poirier wrote:
> The sysFS and Perf access methods can't be allowed to interfere
> with one another. As such introducing guards to access
> functions that prevents moving forward if a TMC is already
> being used.
>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etf.c | 60 +++++++++++++++++++++-
> drivers/hwtracing/coresight/coresight-tmc-etr.c | 68 +++++++++++++++++++++++--
> 2 files changed, 121 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 25fad93b68d4..cc88c15ba45c 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -111,7 +111,7 @@ static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
> CS_LOCK(drvdata->base);
> }
>
> -static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode)
> +static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode)
> {
> bool used = false;
> char *buf = NULL;
> @@ -190,6 +190,54 @@ spin_unlock:
> return 0;
> }
>
> +static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, u32 mode)
> +{
> + int ret = 0;
> + long val;
> + unsigned long flags;
> + struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +
> + /* This shouldn't be happening */
> + if (WARN_ON(mode != CS_MODE_PERF))
> + return -EINVAL;
> +
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> + if (drvdata->reading) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + val = local_xchg(&drvdata->mode, mode);
> + /*
> + * In Perf mode there can be only one writer per sink. There
> + * is also no need to continue if the ETB/ETR is already operated
> + * from sysFS.
> + */
> + if (val != CS_MODE_DISABLED) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + tmc_etb_enable_hw(drvdata);
> +out:
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> +
> + return ret;
> +}
> +
> +static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode)
> +{
> + switch (mode) {
> + case CS_MODE_SYSFS:
> + return tmc_enable_etf_sink_sysfs(csdev, mode);
> + case CS_MODE_PERF:
> + return tmc_enable_etf_sink_perf(csdev, mode);
> + }
> +
> + /* We shouldn't be here */
> + return -EINVAL;
> +}
> +
> static void tmc_disable_etf_sink(struct coresight_device *csdev)
> {
> long val;
> @@ -272,6 +320,7 @@ const struct coresight_ops tmc_etf_cs_ops = {
>
> int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
> {
> + long val;
> enum tmc_mode mode;
> int ret = 0;
> unsigned long flags;
> @@ -290,6 +339,13 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
> goto out;
> }
>
> + val = local_read(&drvdata->mode);
> + /* Don't interfere if operated from Perf */
> + if (val == CS_MODE_PERF) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> /* If drvdata::buf is NULL the trace data has been read already */
> if (drvdata->buf == NULL) {
> ret = -EINVAL;
> @@ -297,7 +353,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata)
> }
>
> /* Disable the TMC if need be */
> - if (local_read(&drvdata->mode) == CS_MODE_SYSFS)
> + if (val == CS_MODE_SYSFS)
> tmc_etb_disable_hw(drvdata);
>
> drvdata->reading = true;
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 4b000f4003a2..a9a94a09186a 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -87,7 +87,7 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
> CS_LOCK(drvdata->base);
> }
>
> -static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
> +static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode)
> {
> bool used = false;
> long val;
> @@ -167,6 +167,54 @@ spin_unlock:
> return 0;
> }
>
> +static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, u32 mode)
> +{
> + int ret = 0;
> + long val;
> + unsigned long flags;
> + struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> +
> + /* This shouldn't be happening */
> + if (WARN_ON(mode != CS_MODE_PERF))
> + return -EINVAL;
> +
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> + if (drvdata->reading) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + val = local_xchg(&drvdata->mode, mode);
> + /*
> + * In Perf mode there can be only one writer per sink. There
> + * is also no need to continue if the ETR is already operated
> + * from sysFS.
> + */
> + if (val != CS_MODE_DISABLED) {

Could val be CS_MODE_PERF ? In other words, should we be checking :
if (val == CS_MODE_SYSFS) instead ?

Suzuki

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