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[RESEND PATCH V4 17/26] coresight: etb10: moving to local atomic operations

From Mathieu Poirier <mathieu.poirier@linaro.org>
Newsgroups linux.kernel
Subject [RESEND PATCH V4 17/26] coresight: etb10: moving to local atomic operations
Date 2015-11-23 19:40 +0100
Message-ID <qy4bW-5B2-69@gated-at.bofh.it> (permalink)
References <qy4bT-5B2-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Moving to use local atomic operations to take advantage of the
lockless implementation, something that will come handy when
the ETB is accessed from the Perf subsystem. Also changing the
name of the variable to something more meaningful.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-etb10.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 1301edc44629..09e306361e4f 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -10,6 +10,7 @@
  * GNU General Public License for more details.
  */
 
+#include <asm/local.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -71,7 +72,7 @@
  * @csdev:	component vitals needed by the framework.
  * @miscdev:	specifics to handle "/dev/xyz.etb" entry.
  * @spinlock:	only one at a time pls.
- * @in_use:	synchronise user space access to etb buffer.
+ * @reading:	synchronise user space access to etb buffer.
  * @buf:	area of memory where ETB buffer content gets sent.
  * @buffer_depth: size of @buf.
  * @enable:	this ETB is being used.
@@ -84,7 +85,7 @@ struct etb_drvdata {
 	struct coresight_device	*csdev;
 	struct miscdevice	miscdev;
 	spinlock_t		spinlock;
-	atomic_t		in_use;
+	local_t			reading;
 	u8			*buf;
 	u32			buffer_depth;
 	bool			enable;
@@ -277,7 +278,7 @@ static int etb_open(struct inode *inode, struct file *file)
 	struct etb_drvdata *drvdata = container_of(file->private_data,
 						   struct etb_drvdata, miscdev);
 
-	if (atomic_cmpxchg(&drvdata->in_use, 0, 1))
+	if (local_cmpxchg(&drvdata->reading, 0, 1))
 		return -EBUSY;
 
 	dev_dbg(drvdata->dev, "%s: successfully opened\n", __func__);
@@ -313,7 +314,7 @@ static int etb_release(struct inode *inode, struct file *file)
 {
 	struct etb_drvdata *drvdata = container_of(file->private_data,
 						   struct etb_drvdata, miscdev);
-	atomic_set(&drvdata->in_use, 0);
+	local_set(&drvdata->reading, 0);
 
 	dev_dbg(drvdata->dev, "%s: released\n", __func__);
 	return 0;
-- 
1.9.1

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[RESEND PATCH V4 00/26] Coresight integration with perf Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 03/26] coresight: etm3x: unlocking tracers in default arch init Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 22/26] coresight: updating documentation to reflect integration with perf Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 14/26] coresight: etm3x: adding perf_get/set_config() API Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 13/26] coresight: etm3x: implementing user/kernel mode tracing Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 12/26] coresight: etm3x: consolidating initial config Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 19/26] coresight: etb10: implementing AUX space API Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 21/26] coresight: introducing a global trace ID function Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 10/26] coresight: etm3x: set progbit to stop trace collection Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 16/26] perf: changing pmu::setup_aux() parameter to include event Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 23/26] perf tools: making function set_max_cpu_num() non static Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 11/26] coresight: etm3x: changing default trace configuration Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 20/26] coresight: etm-perf: new PMU driver for ETM tracers Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 26/26] perf tools: adding coresight etm PMU record capabilities Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 25/26] perf tools: making coresight PMU listable Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 24/26] perf tools: adding perf_session to *info_prive_size() Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 15/26] coresight: etm3x: implementing perf_enable/disable() API Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 17/26] coresight: etb10: moving to local atomic operations Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 18/26] coresight: adding operation mode for sink->enable() Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:40 +0100
  [RESEND PATCH V4 01/26] coresight: etm3x: moving etm_readl/writel to header file Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:50 +0100
  [RESEND PATCH V4 05/26] coresight: etm3x: implementing 'cpu_id()' API Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:50 +0100
  [RESEND PATCH V4 09/26] coresight: add API to get sink from path Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:50 +0100
  [RESEND PATCH V4 08/26] coresight: etm3x: adding operation mode for etm_enable() Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:50 +0100
  [RESEND PATCH V4 06/26] coresight: associating path with session rather than tracer Mathieu Poirier <mathieu.poirier@linaro.org> - 2015-11-23 19:50 +0100

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