[dm-devel] [PATCH 25/42] Make log_pthread more robust

[Hannes Reinecke]

We don't need to allocate memory for mutexes, we can just
be using static variables. And valgrind complained about
logqueue flush from shutdown, so don't do this.
The normal shutdown process should be flushing the log
queue anyway.

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 libmultipath/log_pthread.c |  101 +++++++++++++++++++++++++++++--------------
 libmultipath/log_pthread.h |   10 +++--
 2 files changed, 74 insertions(+), 37 deletions(-)

diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c
index d701ba1..9e92a70 100644
--- a/libmultipath/log_pthread.c
+++ b/libmultipath/log_pthread.c
@@ -13,20 +13,41 @@
 #include "log.h"
 #include "lock.h"
 
+pthread_t log_thr;
+
+pthread_mutex_t logq_lock;
+pthread_mutex_t logev_lock;
+pthread_cond_t logev_cond;
+
+int logq_running;
+
+static void
+sigusr1 (int sig)
+{
+	pthread_mutex_lock(&logq_lock);
+	log_reset("multipathd");
+	pthread_mutex_unlock(&logq_lock);
+}
+
 void log_safe (int prio, const char * fmt, va_list ap)
 {
 	sigset_t old;
 
+	if (log_thr == (pthread_t)0) {
+		syslog(prio, fmt, ap);
+		return;
+	}
+
 	block_signal(SIGUSR1, &old);
 	block_signal(SIGHUP, NULL);
 
-	pthread_mutex_lock(logq_lock);
+	pthread_mutex_lock(&logq_lock);
 	log_enqueue(prio, fmt, ap);
-	pthread_mutex_unlock(logq_lock);
+	pthread_mutex_unlock(&logq_lock);
 
-	pthread_mutex_lock(logev_lock);
-	pthread_cond_signal(logev_cond);
-	pthread_mutex_unlock(logev_lock);
+	pthread_mutex_lock(&logev_lock);
+	pthread_cond_signal(&logev_cond);
+	pthread_mutex_unlock(&logev_lock);
 
 	pthread_sigmask(SIG_SETMASK, &old, NULL);
 }
@@ -36,9 +57,9 @@ static void flush_logqueue (void)
 	int empty;
 
 	do {
-		pthread_mutex_lock(logq_lock);
+		pthread_mutex_lock(&logq_lock);
 		empty = log_dequeue(la->buff);
-		pthread_mutex_unlock(logq_lock);
+		pthread_mutex_unlock(&logq_lock);
 		if (!empty)
 			log_syslog(la->buff);
 	} while (empty == 0);
@@ -46,15 +67,30 @@ static void flush_logqueue (void)
 
 static void * log_thread (void * et)
 {
+	struct sigaction sig;
+	int running;
+
+	sig.sa_handler = sigusr1;
+	sigemptyset(&sig.sa_mask);
+	sig.sa_flags = 0;
+	if (sigaction(SIGUSR1, &sig, NULL) < 0)
+		logdbg(stderr, "Cannot set signal handler");
+
+	pthread_mutex_lock(&logev_lock);
+	logq_running = 1;
+	pthread_mutex_unlock(&logev_lock);
+
 	mlockall(MCL_CURRENT | MCL_FUTURE);
 	logdbg(stderr,"enter log_thread\n");
 
 	while (1) {
-		pthread_mutex_lock(logev_lock);
-		pthread_cond_wait(logev_cond, logev_lock);
-		pthread_mutex_unlock(logev_lock);
-
-		flush_logqueue();
+		pthread_mutex_lock(&logev_lock);
+		pthread_cond_wait(&logev_cond, &logev_lock);
+		running = logq_running;
+		pthread_mutex_unlock(&logev_lock);
+		if (!running)
+			break;
+		log_thread_flush();
 	}
 	return NULL;
 }
@@ -63,19 +99,18 @@ void log_thread_start (pthread_attr_t *attr)
 {
 	logdbg(stderr,"enter log_thread_start\n");
 
-	logq_lock = (pthread_mutex_t *) malloc(sizeof(pthread_mutex_t));
-	logev_lock = (pthread_mutex_t *) malloc(sizeof(pthread_mutex_t));
-	logev_cond = (pthread_cond_t *) malloc(sizeof(pthread_cond_t));
-
-	pthread_mutex_init(logq_lock, NULL);
-	pthread_mutex_init(logev_lock, NULL);
-	pthread_cond_init(logev_cond, NULL);
+	pthread_mutex_init(&logq_lock, NULL);
+	pthread_mutex_init(&logev_lock, NULL);
+	pthread_cond_init(&logev_cond, NULL);
 
 	if (log_init("multipathd", 0)) {
 		fprintf(stderr,"can't initialize log buffer\n");
 		exit(1);
 	}
-	pthread_create(&log_thr, attr, log_thread, NULL);
+	if (pthread_create(&log_thr, attr, log_thread, NULL)) {
+		fprintf(stderr,"can't start log thread\n");
+		exit(1);
+	}
 
 	return;
 }
@@ -84,22 +119,22 @@ void log_thread_stop (void)
 {
 	logdbg(stderr,"enter log_thread_stop\n");
 
-	pthread_mutex_lock(logq_lock);
+	pthread_mutex_lock(&logev_lock);
+	logq_running = 0;
+	pthread_cond_signal(&logev_cond);
+	pthread_mutex_unlock(&logev_lock);
+
+	pthread_mutex_lock(&logq_lock);
 	pthread_cancel(log_thr);
-	pthread_mutex_unlock(logq_lock);
+	pthread_mutex_unlock(&logq_lock);
 	pthread_join(log_thr, NULL);
+	log_thr = (pthread_t)0;
 
 	flush_logqueue();
 
-	pthread_mutex_destroy(logq_lock);
-	pthread_mutex_destroy(logev_lock);
-	pthread_cond_destroy(logev_cond);
-
-	free(logq_lock);
-	logq_lock = NULL;
-	free(logev_lock);
-	logev_lock = NULL;
-	free(logev_cond);
-	logev_cond = NULL;
-	free_logarea();
+	pthread_mutex_destroy(&logq_lock);
+	pthread_mutex_destroy(&logev_lock);
+	pthread_cond_destroy(&logev_cond);
+
+	log_close();
 }
diff --git a/libmultipath/log_pthread.h b/libmultipath/log_pthread.h
index 77780d8..f3b70ea 100644
--- a/libmultipath/log_pthread.h
+++ b/libmultipath/log_pthread.h
@@ -3,11 +3,13 @@
 
 #include <pthread.h>
 
-pthread_t log_thr;
+extern pthread_t log_thr;
 
-pthread_mutex_t *logq_lock;
-pthread_mutex_t *logev_lock;
-pthread_cond_t *logev_cond;
+extern pthread_mutex_t logq_lock;
+extern pthread_mutex_t logev_lock;
+extern pthread_cond_t logev_cond;
+
+extern int logq_running;
 
 void log_safe(int prio, const char * fmt, va_list ap);
 void log_thread_start(pthread_attr_t *attr);
-- 
1.7.4.2