[dm-devel] [PATCH 1/7] libmultipath: move logq_lock handling to log.c

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

logq_lock protects internal data structures of log.c, and should
be handled there. This patch doesn't change functionality, except
improving cancel-safety somewhat.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 libmultipath/log.c         | 34 ++++++++++++++++++++++++++++++++--
 libmultipath/log_pthread.c |  9 ---------
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/libmultipath/log.c b/libmultipath/log.c
index debd36d..7f33787 100644
--- a/libmultipath/log.c
+++ b/libmultipath/log.c
@@ -9,13 +9,16 @@
 #include <string.h>
 #include <syslog.h>
 #include <time.h>
+#include <pthread.h>
 
 #include "memory.h"
 #include "log.h"
+#include "util.h"
 
 #define ALIGN(len, s) (((len)+(s)-1)/(s)*(s))
 
 struct logarea* la;
+static pthread_mutex_t logq_lock = PTHREAD_MUTEX_INITIALIZER;
 
 #if LOGDBG
 static void dump_logarea (void)
@@ -101,12 +104,17 @@ void log_close (void)
 
 void log_reset (char *program_name)
 {
+	pthread_mutex_lock(&logq_lock);
+	pthread_cleanup_push(cleanup_mutex, &logq_lock);
+
 	closelog();
 	tzset();
 	openlog(program_name, 0, LOG_DAEMON);
+
+	pthread_cleanup_pop(1);
 }
 
-int log_enqueue (int prio, const char * fmt, va_list ap)
+static int _log_enqueue(int prio, const char * fmt, va_list ap)
 {
 	int len, fwd;
 	char buff[MAX_MSG_SIZE];
@@ -165,7 +173,18 @@ int log_enqueue (int prio, const char * fmt, va_list ap)
 	return 0;
 }
 
-int log_dequeue (void * buff)
+int log_enqueue(int prio, const char *fmt, va_list ap)
+{
+	int ret;
+
+	pthread_mutex_lock(&logq_lock);
+	pthread_cleanup_push(cleanup_mutex, &logq_lock);
+	ret = _log_enqueue(prio, fmt, ap);
+	pthread_cleanup_pop(1);
+	return ret;
+}
+
+static int _log_dequeue(void *buff)
 {
 	struct logmsg * src = (struct logmsg *)la->head;
 	struct logmsg * dst = (struct logmsg *)buff;
@@ -194,6 +213,17 @@ int log_dequeue (void * buff)
 	return 0;
 }
 
+int log_dequeue(void *buff)
+{
+	int ret;
+
+	pthread_mutex_lock(&logq_lock);
+	pthread_cleanup_push(cleanup_mutex, &logq_lock);
+	ret = _log_dequeue(buff);
+	pthread_cleanup_pop(1);
+	return ret;
+}
+
 /*
  * this one can block under memory pressure
  */
diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c
index 0d48c52..6599210 100644
--- a/libmultipath/log_pthread.c
+++ b/libmultipath/log_pthread.c
@@ -18,7 +18,6 @@
 static pthread_t log_thr;
 
 /* logev_lock must not be taken with logq_lock held */
-static pthread_mutex_t logq_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t logev_lock = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t logev_cond = PTHREAD_COND_INITIALIZER;
 
@@ -41,10 +40,7 @@ void log_safe (int prio, const char * fmt, va_list ap)
 	running = logq_running;
 
 	if (running) {
-		pthread_mutex_lock(&logq_lock);
-		pthread_cleanup_push(cleanup_mutex, &logq_lock);
 		log_enqueue(prio, fmt, ap);
-		pthread_cleanup_pop(1);
 
 		log_messages_pending = 1;
 		pthread_cond_signal(&logev_cond);
@@ -60,9 +56,7 @@ static void flush_logqueue (void)
 	int empty;
 
 	do {
-		pthread_mutex_lock(&logq_lock);
 		empty = log_dequeue(la->buff);
-		pthread_mutex_unlock(&logq_lock);
 		if (!empty)
 			log_syslog(la->buff);
 	} while (empty == 0);
@@ -138,10 +132,7 @@ void log_thread_start (pthread_attr_t *attr)
 void log_thread_reset (void)
 {
 	logdbg(stderr,"resetting log\n");
-
-	pthread_mutex_lock(&logq_lock);
 	log_reset("multipathd");
-	pthread_mutex_unlock(&logq_lock);
 }
 
 void log_thread_stop (void)
-- 
2.29.0