[dm-devel] [PATCH 74/78] Allow specific CLI commands to run unlocked

[Hannes Reinecke]

When multipath is busy with checking paths or processing udev
events it'll take the vector lock, causing the CLI
to become unresponsive.
This patch allows certain CLI commands to not wait for the vector
lock, so that those commands will always succeed.

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 multipathd/cli.c  | 26 +++++++++++++++++++++++++-
 multipathd/cli.h  |  2 ++
 multipathd/main.c | 17 ++++++-----------
 3 files changed, 33 insertions(+), 12 deletions(-)

diff --git a/multipathd/cli.c b/multipathd/cli.c
index acc4249..2d3d02d 100644
--- a/multipathd/cli.c
+++ b/multipathd/cli.c
@@ -1,8 +1,11 @@
 /*
  * Copyright (c) 2005 Christophe Varoqui
  */
+#include <pthread.h>
 #include <memory.h>
 #include <vector.h>
+#include <structs.h>
+#include <structs_vec.h>
 #include <parser.h>
 #include <util.h>
 #include <version.h>
@@ -99,6 +102,19 @@ set_handler_callback (unsigned long fp, int (*fn)(void *, char **, int *, void *
 	if (!h)
 		return 1;
 	h->fn = fn;
+	h->locked = 1;
+	return 0;
+}
+
+int
+set_unlocked_handler_callback (unsigned long fp,int (*fn)(void *, char **, int *, void *))
+{
+	struct handler * h = find_handler(fp);
+
+	if (!h)
+		return 1;
+	h->fn = fn;
+	h->locked = 0;
 	return 0;
 }
 
@@ -396,7 +412,15 @@ parse_cmd (char * cmd, char ** reply, int * len, void * data)
 	/*
 	 * execute handler
 	 */
-	r = h->fn(cmdvec, reply, len, data);
+	if (h->locked) {
+		struct vectors * vecs = (struct vectors *)data;
+		pthread_cleanup_push(cleanup_lock, &vecs->lock);
+		lock(vecs->lock);
+		pthread_testcancel();
+		r = h->fn(cmdvec, reply, len, data);
+		lock_cleanup_pop(vecs->lock);
+	} else
+		r = h->fn(cmdvec, reply, len, data);
 	free_keys(cmdvec);
 
 	return r;
diff --git a/multipathd/cli.h b/multipathd/cli.h
index 09fdc68..b35a315 100644
--- a/multipathd/cli.h
+++ b/multipathd/cli.h
@@ -82,12 +82,14 @@ struct key {
 
 struct handler {
 	unsigned long fingerprint;
+	int locked;
 	int (*fn)(void *, char **, int *, void *);
 };
 
 int alloc_handlers (void);
 int add_handler (unsigned long fp, int (*fn)(void *, char **, int *, void *));
 int set_handler_callback (unsigned long fp, int (*fn)(void *, char **, int *, void *));
+int set_unlocked_handler_callback (unsigned long fp, int (*fn)(void *, char **, int *, void *));
 int parse_cmd (char * cmd, char ** reply, int * len, void *);
 int load_keys (void);
 char * get_keyparam (vector v, unsigned long code);
diff --git a/multipathd/main.c b/multipathd/main.c
index 9e7bf4f..ab2a3a7 100644
--- a/multipathd/main.c
+++ b/multipathd/main.c
@@ -773,10 +773,6 @@ uxsock_trigger (char * str, char ** reply, int * len, void * trigger_data)
 	*len = 0;
 	vecs = (struct vectors *)trigger_data;
 
-	pthread_cleanup_push(cleanup_lock, &vecs->lock);
-	lock(vecs->lock);
-	pthread_testcancel();
-
 	r = parse_cmd(str, reply, len, vecs);
 
 	if (r > 0) {
@@ -791,7 +787,6 @@ uxsock_trigger (char * str, char ** reply, int * len, void * trigger_data)
 	}
 	/* else if (r < 0) leave *reply alone */
 
-	lock_cleanup_pop(vecs->lock);
 	return r;
 }
 
@@ -903,16 +898,16 @@ uxlsnrloop (void * ap)
 	set_handler_callback(LIST+PATHS+FMT, cli_list_paths_fmt);
 	set_handler_callback(LIST+PATH, cli_list_path);
 	set_handler_callback(LIST+MAPS, cli_list_maps);
-	set_handler_callback(LIST+STATUS, cli_list_status);
-	set_handler_callback(LIST+DAEMON, cli_list_daemon);
+	set_unlocked_handler_callback(LIST+STATUS, cli_list_status);
+	set_unlocked_handler_callback(LIST+DAEMON, cli_list_daemon);
 	set_handler_callback(LIST+MAPS+STATUS, cli_list_maps_status);
 	set_handler_callback(LIST+MAPS+STATS, cli_list_maps_stats);
 	set_handler_callback(LIST+MAPS+FMT, cli_list_maps_fmt);
 	set_handler_callback(LIST+MAPS+TOPOLOGY, cli_list_maps_topology);
 	set_handler_callback(LIST+TOPOLOGY, cli_list_maps_topology);
 	set_handler_callback(LIST+MAP+TOPOLOGY, cli_list_map_topology);
-	set_handler_callback(LIST+CONFIG, cli_list_config);
-	set_handler_callback(LIST+BLACKLIST, cli_list_blacklist);
+	set_unlocked_handler_callback(LIST+CONFIG, cli_list_config);
+	set_unlocked_handler_callback(LIST+BLACKLIST, cli_list_blacklist);
 	set_handler_callback(LIST+DEVICES, cli_list_devices);
 	set_handler_callback(LIST+WILDCARDS, cli_list_wildcards);
 	set_handler_callback(ADD+PATH, cli_add_path);
@@ -932,8 +927,8 @@ uxlsnrloop (void * ap)
 	set_handler_callback(RESTOREQ+MAP, cli_restore_queueing);
 	set_handler_callback(DISABLEQ+MAPS, cli_disable_all_queueing);
 	set_handler_callback(RESTOREQ+MAPS, cli_restore_all_queueing);
-	set_handler_callback(QUIT, cli_quit);
-	set_handler_callback(SHUTDOWN, cli_shutdown);
+	set_unlocked_handler_callback(QUIT, cli_quit);
+	set_unlocked_handler_callback(SHUTDOWN, cli_shutdown);
 	set_handler_callback(GETPRSTATUS+MAP, cli_getprstatus);
 	set_handler_callback(SETPRSTATUS+MAP, cli_setprstatus);
 	set_handler_callback(UNSETPRSTATUS+MAP, cli_unsetprstatus);
-- 
1.8.4.5