linux-kernel - [PATCH 2/6] stm class: adds a loop to extract the first valid STM device name

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Date:	Mon,  1 Feb 2016 16:19:47 +0800
From:	Chunyan Zhang <zhang.chunyan@...aro.org>
To:	mathieu.poirier@...aro.org, alexander.shishkin@...ux.intel.com
Cc:	robh@...nel.org, broonie@...nel.org, pratikp@...eaurora.org,
	nicolas.guion@...com, corbet@....net, mark.rutland@....com,
	zhang.lyra@...il.com, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-api@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: [PATCH 2/6] stm class: adds a loop to extract the first valid STM device name

The node name of STM master management policy is a concatenation of an
STM device name to which this policy applies and following an arbitrary
string, these two strings are concatenated with a dot.

This patch adds a loop for extracting the STM device name when an
arbitrary number of dot(s) are found in this STM device name.

Signed-off-by: Chunyan Zhang <zhang.chunyan@...aro.org>
---
 drivers/hwtracing/stm/policy.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index 11ab6d0..691686e 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -321,21 +321,26 @@ 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
+	 * <policy_name> is an arbitrary string, when an arbitrary
+	 * number of dot(s) are found in the <device_name>, the
+	 * first matched STM device name would be extracted.
 	 */
-	p = strchr(devname, '.');
-	if (!p) {
-		kfree(devname);
-		return ERR_PTR(-EINVAL);
-	}
+	for (p = devname; ; p++) {
+		p = strchr(p, '.');
+		if (!p) {
+			kfree(devname);
+			return ERR_PTR(-EINVAL);
+		}
 
-	*p++ = '\0';
+		*p = '\0';
 
-	stm = stm_find_device(devname);
-	kfree(devname);
+		stm = stm_find_device(devname);
+		if (stm)
+			break;
+		*p = '.';
+	};
 
-	if (!stm)
-		return ERR_PTR(-ENODEV);
+	kfree(devname);
 
 	mutex_lock(&stm->policy_mutex);
 	if (stm->policy) {
-- 
1.9.1