[PATCH v7 11/20] coresight: etm4x: Set active path on target CPU

[Leo Yan]

Set and clear the path pointer on the target CPU during ETM enable
and disable operations to avoid race conditions when retrieving the
pointer in CPU PM callbacks.

Tested-by: James Clark <james.clark at linaro.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun at arm.com>
Reviewed-by: James Clark <james.clark at linaro.org>
Signed-off-by: Leo Yan <leo.yan at arm.com>
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 4a9b226781a5c2ab6efcadf08614de58bcd4043a..1f100e8bbcc775a1bdc5f8b27ff15dbcaf030a63 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -234,6 +234,7 @@ void etm4_release_trace_id(struct etmv4_drvdata *drvdata)
 
 struct etm4_enable_arg {
 	struct etmv4_drvdata *drvdata;
+	struct coresight_path *path;
 	int rc;
 };
 
@@ -621,8 +622,12 @@ static void etm4_enable_sysfs_smp_call(void *info)
 	arg->rc = etm4_enable_hw(arg->drvdata);
 
 	/* The tracer didn't start */
-	if (arg->rc)
+	if (arg->rc) {
 		coresight_set_mode(csdev, CS_MODE_DISABLED);
+		return;
+	}
+
+	csdev->path = arg->path;
 }
 
 /*
@@ -890,9 +895,13 @@ static int etm4_enable_perf(struct coresight_device *csdev,
 
 out:
 	/* Failed to start tracer; roll back to DISABLED mode */
-	if (ret)
+	if (ret) {
 		coresight_set_mode(csdev, CS_MODE_DISABLED);
-	return ret;
+		return ret;
+	}
+
+	csdev->path = path;
+	return 0;
 }
 
 static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_path *path)
@@ -922,6 +931,7 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
 	 * ensures that register writes occur when cpu is powered.
 	 */
 	arg.drvdata = drvdata;
+	arg.path = path;
 	ret = smp_call_function_single(drvdata->cpu,
 				       etm4_enable_sysfs_smp_call, &arg, 1);
 	if (!ret)
@@ -1063,6 +1073,7 @@ static void etm4_disable_sysfs_smp_call(void *info)
 
 	etm4_disable_hw(drvdata);
 
+	drvdata->csdev->path = NULL;
 	coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED);
 }
 
@@ -1092,6 +1103,7 @@ static int etm4_disable_perf(struct coresight_device *csdev,
 	/* TRCVICTLR::SSSTATUS, bit[9] */
 	filters->ssstatus = (control & BIT(9));
 
+	drvdata->csdev->path = NULL;
 	coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED);
 
 	/*

-- 
2.34.1