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Subject[PATCH 27/32] coresight: tmc-etr: Introduce the notion of reference counting to ETR devices
Date
This patch adds reference counting to struct etr_buf so that, in CPU-wide
trace scenarios, shared buffers can be disposed of when no longer used.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Robert Walker <robert.walker@arm.com>
---
drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++++
drivers/hwtracing/coresight/coresight-tmc.h | 3 +++
2 files changed, 8 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 1acad42184e6..de33c0391186 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -8,6 +8,7 @@
#include <linux/coresight.h>
#include <linux/dma-mapping.h>
#include <linux/iommu.h>
+#include <linux/refcount.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
@@ -1222,7 +1223,11 @@ get_perf_etr_buf_per_thread(struct tmc_drvdata *drvdata,
* with memory allocation.
*/
etr_buf = alloc_etr_buf(drvdata, event, nr_pages, pages, snapshot);
+ if (IS_ERR(etr_buf))
+ goto out;

+ refcount_set(&etr_buf->refcount, 1);
+out:
return etr_buf;
}

diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 487c53701e9c..ee44906dffe8 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -9,6 +9,7 @@

#include <linux/dma-mapping.h>
#include <linux/miscdevice.h>
+#include <linux/refcount.h>

#define TMC_RSZ 0x004
#define TMC_STS 0x00c
@@ -133,6 +134,7 @@ struct etr_buf_operations;

/**
* struct etr_buf - Details of the buffer used by ETR
+ * refcount ; Number of sources currently using this etr_buf.
* @mode : Mode of the ETR buffer, contiguous, Scatter Gather etc.
* @full : Trace data overflow
* @size : Size of the buffer.
@@ -143,6 +145,7 @@ struct etr_buf_operations;
* @private : Backend specific information for the buf
*/
struct etr_buf {
+ refcount_t refcount;
enum etr_mode mode;
bool full;
ssize_t size;
--
2.17.1
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