diff mbox

[V2,5/6] coresight: adding sink parameter to function coresight_build_path()

Message ID 1469047100-18131-6-git-send-email-mathieu.poirier@linaro.org
State Superseded
Headers show

Commit Message

Mathieu Poirier July 20, 2016, 8:38 p.m. UTC 
Up to now function coresight_build_path() was counting on a sink to
have been selected (from sysFS) prior to being called.  This patch
adds a string argument so that a sink matching the argument can be
selected.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

---
 drivers/hwtracing/coresight/coresight-etm-perf.c |  2 +-
 drivers/hwtracing/coresight/coresight-priv.h     |  3 +-
 drivers/hwtracing/coresight/coresight.c          | 40 +++++++++++++++---------
 3 files changed, 29 insertions(+), 16 deletions(-)

-- 
2.7.4

Comments

Mathieu Poirier July 21, 2016, 3:05 p.m. UTC | #1 
On 21 July 2016 at 04:49, Suzuki K Poulose <Suzuki.Poulose@arm.com> wrote:
> On 20/07/16 21:38, Mathieu Poirier wrote:

>>

>> Up to now function coresight_build_path() was counting on a sink to

>> have been selected (from sysFS) prior to being called.  This patch

>> adds a string argument so that a sink matching the argument can be

>> selected.

>>

>

>>  static int _coresight_build_path(struct coresight_device *csdev,

>> -                                struct list_head *path)

>> +                                struct list_head *path, const char *sink)

>>  {

>>         int i;

>>         bool found = false;

>>         struct coresight_node *node;

>>

>> -       /* An activated sink has been found.  Enqueue the element */

>> -       if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||

>> -            csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) &&

>> csdev->activated)

>> -               goto out;

>> +       /*

>> +        * First see if we are dealing with a sink.  If we have one check

>> if

>> +        * it was selected via sysFS or the perf cmd line.

>> +        */

>> +       if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||

>> +           csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {

>> +               /* Activated via perf cmd line */

>> +               if (sink && !strcmp(dev_name(&csdev->dev), sink))

>> +                       goto out;

>> +               /* Activated via sysFS */

>> +               if (csdev->activated)

>

>

> When a sink is specified, should we skip an activated sink and continue to

> find the specified one ? or at least fail with an error as we may not be

> using

> the sink specified by the user ?

> i.e may be :

>                 if (!sink && csdev->activated)

>                         goto out;



I understand your point.  My goal though is to discourage people from
meddling in sysFS when using CS from the perf interface.  As such if
any code is to be added here, it would be to report an error when both
a sink has been specified from perf and activated from sysFS.

>

> Suzuki
diff mbox

Patch

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index f4174f36c5a0..f8c7a8733b23 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -184,7 +184,7 @@  static void *etm_setup_aux(struct perf_event *event, void **pages,
 		 * list of devices from source to sink that can be
 		 * referenced later when the path is actually needed.
 		 */
-		event_data->path[cpu] = coresight_build_path(csdev);
+		event_data->path[cpu] = coresight_build_path(csdev, NULL);
 		if (!event_data->path[cpu])
 			goto err;
 	}
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index ad975c58080d..3cb574b3cdd9 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -94,7 +94,8 @@  static inline void CS_UNLOCK(void __iomem *addr)
 void coresight_disable_path(struct list_head *path);
 int coresight_enable_path(struct list_head *path, u32 mode);
 struct coresight_device *coresight_get_sink(struct list_head *path);
-struct list_head *coresight_build_path(struct coresight_device *csdev);
+struct list_head *coresight_build_path(struct coresight_device *csdev,
+				       const char *sink);
 void coresight_release_path(struct list_head *path);
 
 #ifdef CONFIG_CORESIGHT_SOURCE_ETM3X
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index d08d1ab9bba5..cbbb51a16dff 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -372,30 +372,41 @@  struct coresight_device *coresight_get_sink(struct list_head *path)
  * _coresight_build_path - recursively build a path from a @csdev to a sink.
  * @csdev:	The device to start from.
  * @path:	The list to add devices to.
+ * @sink:	The name of the sink this path should connect with.
  *
- * The tree of Coresight device is traversed until an activated sink is
- * found.  From there the sink is added to the list along with all the
- * devices that led to that point - the end result is a list from source
- * to sink. In that list the source is the first device and the sink the
- * last one.
+ * The tree of Coresight device is traversed until an activated sink or
+ * the one specified by @sink is found.
+ * From there the sink is added to the list along with all the devices that
+ * led to that point - the end result is a list from source to sink. In that
+ * list the source is the first device and the sink the last one.
  */
 static int _coresight_build_path(struct coresight_device *csdev,
-				 struct list_head *path)
+				 struct list_head *path, const char *sink)
 {
 	int i;
 	bool found = false;
 	struct coresight_node *node;
 
-	/* An activated sink has been found.  Enqueue the element */
-	if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
-	     csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) && csdev->activated)
-		goto out;
+	/*
+	 * First see if we are dealing with a sink.  If we have one check if
+	 * it was selected via sysFS or the perf cmd line.
+	 */
+	if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
+	    csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {
+		/* Activated via perf cmd line */
+		if (sink && !strcmp(dev_name(&csdev->dev), sink))
+			goto out;
+		/* Activated via sysFS */
+		if (csdev->activated)
+			goto out;
+	}
 
 	/* Not a sink - recursively explore each port found on this element */
 	for (i = 0; i < csdev->nr_outport; i++) {
 		struct coresight_device *child_dev = csdev->conns[i].child_dev;
 
-		if (child_dev && _coresight_build_path(child_dev, path) == 0) {
+		if (child_dev &&
+		    _coresight_build_path(child_dev, path, sink) == 0) {
 			found = true;
 			break;
 		}
@@ -422,7 +433,8 @@  out:
 	return 0;
 }
 
-struct list_head *coresight_build_path(struct coresight_device *csdev)
+struct list_head *coresight_build_path(struct coresight_device *csdev,
+				       const char *sink)
 {
 	struct list_head *path;
 	int rc;
@@ -433,7 +445,7 @@  struct list_head *coresight_build_path(struct coresight_device *csdev)
 
 	INIT_LIST_HEAD(path);
 
-	rc = _coresight_build_path(csdev, path);
+	rc = _coresight_build_path(csdev, path, sink);
 	if (rc) {
 		kfree(path);
 		return ERR_PTR(rc);
@@ -508,7 +520,7 @@  int coresight_enable(struct coresight_device *csdev)
 	if (csdev->enable)
 		goto out;
 
-	path = coresight_build_path(csdev);
+	path = coresight_build_path(csdev, NULL);
 	if (IS_ERR(path)) {
 		pr_err("building path(s) failed\n");
 		ret = PTR_ERR(path);