[RFC PATCH 03/20] coresight: etm3x: implementing 'cpu_id()' API
From: alexander.shishkin@linux.intel.com (Alexander Shishkin)
Date: 2015-09-30 11:18:57
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Mathieu Poirier [off-list ref] writes:
quoted hunk ↗ jump to hunk
Adding an interface to lookup the CPU a tracer has been affined to along with a source operation allowing external customers to access it. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- drivers/hwtracing/coresight/coresight-etm3x.c | 14 ++++++++++++++ include/linux/coresight.h | 3 +++ 2 files changed, 17 insertions(+)diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c index a44bc3532585..4ce9cfc06e93 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x.c +++ b/drivers/hwtracing/coresight/coresight-etm3x.c@@ -441,6 +441,19 @@ static void etm_config_enable(void *info) spin_unlock(&drvdata->spinlock); } +static int etm_cpu_id(struct coresight_device *csdev) +{ + int cpu; + unsigned long flags; + struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); + + spin_lock_irqsave(&drvdata->spinlock, flags); + cpu = drvdata->cpu; + spin_unlock_irqrestore(&drvdata->spinlock, flags);
Why do you need a spinlock here? Afaict, it never changes and if it would, things would go really bad really fast. Regards, -- Alex