modules_k/cfgutils: add locking around gflags

gflags are stored in shared memory and must thus be protected against
concurrent access.

Reads from an int are atomic on most (all?) real world hardware, so only
modification of the flags is placed under the protection of the lock, not
reads.

modules_k/cfgutils/cfgutils.c

@@ -134,6 +134,7 @@ static char* hash_file = NULL;
 
 static int initial_gflags=0;
 static unsigned int *gflags=0;
+static gen_lock_t *gflags_lock = NULL;
 
 static gen_lock_set_t *_cfg_lock_set = NULL;
 static unsigned int _cfg_lock_size = 0;
@@ -291,14 +292,18 @@ static int fixup_gflags( void** param, int param_no)
 
 static int set_gflag(struct sip_msg *bar, char *flag, char *foo) 
 {
+	lock_get(gflags_lock);
 	(*gflags) |= (unsigned int)(long)flag;
+	lock_release(gflags_lock);
 	return 1;
 }
 
 
 static int reset_gflag(struct sip_msg *bar, char *flag, char *foo)
 {
+	lock_get(gflags_lock);
 	(*gflags) &= ~ ((unsigned int)(long)flag);
+	lock_release(gflags_lock);
 	return 1;
 }
 
@@ -326,7 +331,9 @@ static struct mi_root* mi_set_gflag(struct mi_root* cmd_tree, void* param )
 		goto error;
 	}
 
+	lock_get(gflags_lock);
 	(*gflags) |= flag;
+	lock_release(gflags_lock);
 
 	return init_mi_tree( 200, MI_OK_S, MI_OK_LEN);
 error:
@@ -351,7 +358,9 @@ static struct mi_root*  mi_reset_gflag(struct mi_root* cmd_tree, void* param )
 		goto error;
 	}
 
+	lock_get(gflags_lock);
 	(*gflags) &= ~ flag;
+	lock_release(gflags_lock);
 
 	return init_mi_tree( 200, MI_OK_S, MI_OK_LEN);
 error:
@@ -403,16 +412,19 @@ static struct mi_root*  mi_get_gflags(struct mi_root* cmd_tree, void* param )
 {
 	struct mi_root* rpl_tree= NULL;
 	struct mi_node* node= NULL;
+	static unsigned int flags;
 
 	rpl_tree = init_mi_tree( 200, MI_OK_S, MI_OK_LEN );
 	if(rpl_tree == NULL)
 		return 0;
 
-	node = addf_mi_node_child( &rpl_tree->node, 0, 0, 0, "0x%X",(*gflags));
+	flags = *gflags;
+
+	node = addf_mi_node_child( &rpl_tree->node, 0, 0, 0, "0x%X",(flags));
 	if(node == NULL)
 		goto error;
 
-	node = addf_mi_node_child( &rpl_tree->node, 0, 0, 0, "%u",(*gflags));
+	node = addf_mi_node_child( &rpl_tree->node, 0, 0, 0, "%u",(flags));
 	if(node == NULL)
 		goto error;
 
@@ -764,6 +776,16 @@ static int mod_init(void)
 		return -1;
 	}
 	*gflags=initial_gflags;
+	gflags_lock = lock_alloc();
+	if (gflags_lock==0) {
+		LM_ERR("cannot allocate gflgas lock\n");
+		return -1;
+	}
+	if (lock_init(gflags_lock)==NULL) {
+		LM_ERR("cannot initiate gflags lock\n");
+		lock_dealloc(gflags_lock);
+		return -1;
+	}
 	if(_cfg_lock_size>0 && _cfg_lock_size<=10)
 	{
 		_cfg_lock_size = 1<<_cfg_lock_size;
@@ -784,6 +806,10 @@ static void mod_destroy(void)
 		shm_free(probability);
 	if (gflags)
 		shm_free(gflags);
+	if (gflags_lock) {
+		lock_destroy(gflags_lock);
+		lock_dealloc(gflags_lock);
+	}
 	if(_cfg_lock_set!=NULL)
 	{
 		lock_set_destroy(_cfg_lock_set);