[PATCH v3 22/22] libmultipath: make checker_message thread safe

[Martin Wilck <mwilck@suse.com>]

Get rid of the static char buffer in checker_message()
introduced in the previous "replace message by msgid" patch.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 libmultipath/checkers.c  | 23 ++++++++++++++++++-----
 libmultipath/checkers.h  |  4 +++-
 libmultipath/discovery.c |  9 ++++++---
 multipathd/main.c        | 11 +++++------
 4 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/libmultipath/checkers.c b/libmultipath/checkers.c
index 9a19c9a6..f65a9476 100644
--- a/libmultipath/checkers.c
+++ b/libmultipath/checkers.c
@@ -309,16 +309,29 @@ static const char *_checker_message(const struct checker *c)
 	return NULL;
 }
 
+int checker_has_message(const struct checker *c)
+{
+	const char *msg = _checker_message(c);
+
+	if (msg == NULL || *msg == '\0')
+		return 0;
+	return 1;
+}
+
 char *checker_message(const struct checker *c)
 {
-	static char buf[CHECKER_MSG_LEN];
+	char *buf;
 	const char *msg = _checker_message(c);
+	int len;
 
 	if (msg == NULL || *msg == '\0')
-		*buf = '\0';
-	else
-		snprintf(buf, sizeof(buf), "%s checker%s",
-			 c->cls->name, msg);
+		return NULL;
+
+	len = CHECKER_NAME_LEN + 8 + CHECKER_MSG_LEN;
+	buf = MALLOC(len);
+	if (buf == NULL)
+		return NULL;
+	snprintf(buf, len, "%s checker%s", c->cls->name, msg);
 	return buf;
 }
 
diff --git a/libmultipath/checkers.h b/libmultipath/checkers.h
index 834efcfe..2c71e40c 100644
--- a/libmultipath/checkers.h
+++ b/libmultipath/checkers.h
@@ -145,7 +145,9 @@ int checker_check (struct checker *, int);
 int checker_selected(const struct checker *);
 int checker_is_sync(const struct checker *);
 const char *checker_name (const struct checker *);
-char *checker_message (const struct checker *);
+/* checker_message(): returned pointer is malloc()d */
+char *checker_message(const struct checker *);
+int checker_has_message(const struct checker *);
 void checker_clear_message (struct checker *c);
 void checker_get(const char *, struct checker *, const char *);
 
diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index 467ece7a..0bcd3c39 100644
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -1588,9 +1588,12 @@ get_state (struct path * pp, struct config *conf, int daemon, int oldstate)
 	condlog(3, "%s: %s state = %s", pp->dev,
 		checker_name(c), checker_state_name(state));
 	if (state != PATH_UP && state != PATH_GHOST &&
-	    strlen(checker_message(c)))
-		condlog(3, "%s: checker msg is \"%s\"",
-			pp->dev, checker_message(c));
+	    checker_has_message(c)) {
+		char *msg = checker_message(c);
+
+		condlog(3, "%s: checker msg is \"%s\"", pp->dev, msg);
+		FREE(msg);
+	}
 	return state;
 }
 
diff --git a/multipathd/main.c b/multipathd/main.c
index e80ac906..fcf0d2db 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -95,14 +95,13 @@ do {								\
 		if (pp->offline)				\
 			condlog(lvl, "%s: %s - path offline",	\
 				pp->mpp->alias, pp->dev);	\
-		else {						\
-			const char *__m =			\
+		else if (checker_has_message(&pp->checker)) {	\
+			char *__m =				\
 				checker_message(&pp->checker);	\
 								\
-			if (strlen(__m))			\
-				condlog(lvl, "%s: %s - %s",	\
-					pp->mpp->alias,		\
-					pp->dev, __m);		\
+			condlog(lvl, "%s: %s - %s",		\
+				pp->mpp->alias, pp->dev, __m);	\
+			FREE(__m);				\
 		}						\
 	}							\
 } while(0)
-- 
2.19.1