[PATCH v1 2/5] coresight: Protect unregistration with mutex

[Leo Yan <leo.yan@arm.com>]

The device registration is protected by CoreSight mutex to ensure the
atomic operations when adding a device onto bus.  One the other hand,
the locking is absent when unregister a device.

Use mutex to ensure atomicity on device unregistration.  During
unregistration, unbinding the associated CTI device is not included in
the locking region, as CTI has its own locking mechanism.

Fixes: 8c1d3f79d9ca ("coresight: core: Fix coresight device probe failure issue")
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 drivers/hwtracing/coresight/coresight-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 3e3823d9f991..3eacdcf638df 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -1400,14 +1400,17 @@ EXPORT_SYMBOL_GPL(coresight_register);
 
 void coresight_unregister(struct coresight_device *csdev)
 {
-	etm_perf_del_symlink_sink(csdev);
 	/* Remove references of that device in the topology */
 	if (cti_assoc_ops && cti_assoc_ops->remove)
 		cti_assoc_ops->remove(csdev);
+
+	mutex_lock(&coresight_mutex);
+	etm_perf_del_symlink_sink(csdev);
 	coresight_remove_conns(csdev);
 	coresight_clear_default_sink(csdev);
 	coresight_release_platform_data(csdev, csdev->dev.parent, csdev->pdata);
 	device_unregister(&csdev->dev);
+	mutex_unlock(&coresight_mutex);
 }
 EXPORT_SYMBOL_GPL(coresight_unregister);
 
-- 
2.34.1