[PATCH 4.4 061/131] stm class: Support devices with multiple instances

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 59be422e4ce10e3d49d4c9407a80fab8a9b7bc84 ]

By convention, the name of the stm policy directory in configfs consists of
the device name to which it applies and the actual policy name, separated
by a dot. Now, some devices already have dots in their names that separate
name of the actual device from its instance identifier. Such devices will
result in two (or more, who can tell) dots in the policy directory name.

Existing policy code, however, will treat the first dot as the one that
separates device name from policy name, therefore failing the above case.

This patch makes the last dot in the directory name be the separator, thus
prohibiting dots from being used in policy names.

Suggested-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/hwtracing/stm/policy.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index 94d3abfb737a..1db189657b2b 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -332,10 +332,11 @@ stp_policies_make(struct config_group *group, const char *name)
 
 	/*
 	 * node must look like <device_name>.<policy_name>, where
-	 * <device_name> is the name of an existing stm device and
-	 * <policy_name> is an arbitrary string
+	 * <device_name> is the name of an existing stm device; may
+	 *               contain dots;
+	 * <policy_name> is an arbitrary string; may not contain dots
 	 */
-	p = strchr(devname, '.');
+	p = strrchr(devname, '.');
 	if (!p) {
 		kfree(devname);
 		return ERR_PTR(-EINVAL);
-- 
2.19.1