lib: add API to allow northbound clients to lock/unlock the running configuration

The ability to lock the running configuration to prevent other users
from changing it is a very important one. We already supported
the "configure exclusive" command but the lock was applied to
the CLI users only (other clients like ConfD could still commit
configuration transactions, ignoring the CLI lock). This commit
introduces a global lock for the running configuration that is
shared by all northbound clients, and provides a public API to
manipulate it. This way other northbound clients will also be able
to lock/unlock the running configuration if required (the upcoming
gRPC northbound plugin will have RPCs for that).

NOTE: this is a management-level lock for the running configuration,
not to be confused with low-level locks used to avoid data races.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

1 files changed, 4 insertions, 22 deletions

diff --git a/lib/vty.c b/lib/vty.c
index dae8e8259..da9bee6e1 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -86,9 +86,6 @@ static vector Vvty_serv_thread;
 /* Current directory. */
 char *vty_cwd = NULL;
 
-/* Exclusive configuration lock. */
-struct vty *vty_exclusive_lock;
-
 /* Login password check. */
 static int no_password_check = 0;
 
@@ -2369,7 +2366,7 @@ static void vty_read_file(struct nb_config *config, FILE *confp)
 	if (config == NULL && vty->candidate_config
 	    && frr_get_cli_mode() == FRR_CLI_TRANSACTIONAL) {
 		ret = nb_candidate_commit(vty->candidate_config, NB_CLIENT_CLI,
-					  true, "Read configuration file",
+					  vty, true, "Read configuration file",
 					  NULL);
 		if (ret != NB_OK && ret != NB_ERR_NO_CHANGES)
 			zlog_err("%s: failed to read configuration file.",
@@ -2601,8 +2598,8 @@ void vty_log_fixed(char *buf, size_t len)
 
 int vty_config_enter(struct vty *vty, bool private_config, bool exclusive)
 {
-	if (exclusive && !vty_config_exclusive_lock(vty)) {
-		vty_out(vty, "VTY configuration is locked by other VTY\n");
+	if (exclusive && nb_running_lock(NB_CLIENT_CLI, vty)) {
+		vty_out(vty, "%% Configuration is locked by other client\n");
 		return CMD_WARNING;
 	}
 
@@ -2636,7 +2633,7 @@ void vty_config_exit(struct vty *vty)
 		nb_cli_confirmed_commit_clean(vty);
 	}
 
-	vty_config_exclusive_unlock(vty);
+	(void)nb_running_unlock(NB_CLIENT_CLI, vty);
 
 	if (vty->candidate_config) {
 		if (vty->private_config)
@@ -2651,21 +2648,6 @@ void vty_config_exit(struct vty *vty)
 	vty->config = false;
 }
 
-int vty_config_exclusive_lock(struct vty *vty)
-{
-	if (vty_exclusive_lock == NULL) {
-		vty_exclusive_lock = vty;
-		return 1;
-	}
-	return 0;
-}
-
-void vty_config_exclusive_unlock(struct vty *vty)
-{
-	if (vty_exclusive_lock == vty)
-		vty_exclusive_lock = NULL;
-}
-
 /* Master of the threads. */
 static struct thread_master *vty_master;