Subject: [PATCH 15/20] lockd: introduce lockd_put()
From:   NeilBrown <neilb@suse.de>
To:     "J. Bruce Fields" <bfields@fieldses.org>,
        Chuck Lever <chuck.lever@oracle.com>
Cc:     linux-nfs@vger.kernel.org
Date:   Mon, 29 Nov 2021 15:51:25 +1100
Message-ID: <163816148561.32298.11953626058640056002.stgit@noble.brown>
In-Reply-To: <163816133466.32298.13831616524908720974.stgit@noble.brown>
References: <163816133466.32298.13831616524908720974.stgit@noble.brown>
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There is some cleanup that is duplicated in lockd_down() and the failure
path of lockd_up().
Factor these out into a new lockd_put() and call it from both places.

lockd_put() does *not* take the mutex - that must be held by the caller.
It decrements nlmsvc_users and if that reaches zero, it cleans up.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 fs/lockd/svc.c |   64 ++++++++++++++++++++++++--------------------------------
 1 file changed, 27 insertions(+), 37 deletions(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 9aa499a76159..7f12c280fd30 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -351,14 +351,6 @@ static struct notifier_block lockd_inet6addr_notifier = {
 };
 #endif
 
-static void lockd_unregister_notifiers(void)
-{
-	unregister_inetaddr_notifier(&lockd_inetaddr_notifier);
-#if IS_ENABLED(CONFIG_IPV6)
-	unregister_inet6addr_notifier(&lockd_inet6addr_notifier);
-#endif
-}
-
 static int lockd_start_svc(struct svc_serv *serv)
 {
 	int error;
@@ -450,6 +442,27 @@ static int lockd_create_svc(void)
 	return 0;
 }
 
+static void lockd_put(void)
+{
+	if (WARN(nlmsvc_users <= 0, "lockd_down: no users!\n"))
+		return;
+	if (--nlmsvc_users)
+		return;
+
+	unregister_inetaddr_notifier(&lockd_inetaddr_notifier);
+#if IS_ENABLED(CONFIG_IPV6)
+	unregister_inet6addr_notifier(&lockd_inet6addr_notifier);
+#endif
+
+	if (nlmsvc_task) {
+		kthread_stop(nlmsvc_task);
+		dprintk("lockd_down: service stopped\n");
+		nlmsvc_task = NULL;
+	}
+	nlmsvc_serv = NULL;
+	dprintk("lockd_down: service destroyed\n");
+}
+
 /*
  * Bring up the lockd process if it's not already up.
  */
@@ -461,21 +474,16 @@ int lockd_up(struct net *net, const struct cred *cred)
 
 	error = lockd_create_svc();
 	if (error)
-		goto err_create;
+		goto err;
+	nlmsvc_users++;
 
 	error = lockd_up_net(nlmsvc_serv, net, cred);
 	if (error < 0) {
-		goto err_put;
+		lockd_put();
+		goto err;
 	}
 
-	nlmsvc_users++;
-err_put:
-	if (nlmsvc_users == 0) {
-		lockd_unregister_notifiers();
-		kthread_stop(nlmsvc_task);
-		nlmsvc_serv = NULL;
-	}
-err_create:
+err:
 	mutex_unlock(&nlmsvc_mutex);
 	return error;
 }
@@ -489,25 +497,7 @@ lockd_down(struct net *net)
 {
 	mutex_lock(&nlmsvc_mutex);
 	lockd_down_net(nlmsvc_serv, net);
-	if (nlmsvc_users) {
-		if (--nlmsvc_users)
-			goto out;
-	} else {
-		printk(KERN_ERR "lockd_down: no users! task=%p\n",
-			nlmsvc_task);
-		BUG();
-	}
-
-	if (!nlmsvc_task) {
-		printk(KERN_ERR "lockd_down: no lockd running.\n");
-		BUG();
-	}
-	lockd_unregister_notifiers();
-	kthread_stop(nlmsvc_task);
-	dprintk("lockd_down: service destroyed\n");
-	nlmsvc_serv = NULL;
-	nlmsvc_task = NULL;
-out:
+	lockd_put();
 	mutex_unlock(&nlmsvc_mutex);
 }
 EXPORT_SYMBOL_GPL(lockd_down);