From: Alan Stern <stern@rowland.harvard.edu>
Date: Sun, 25 Jun 2006 12:47:15 +0000 (-0700)
Subject: [PATCH] Allow raw_notifier callouts to unregister themselves
X-Git-Tag: v4.13~44531
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=bbb1747d4e44ce49acc73daa8d66e5f6bd546f1b;p=mirror_ubuntu-bionic-kernel.git

[PATCH] Allow raw_notifier callouts to unregister themselves

Since raw_notifier chains don't benefit from any centralized locking
protections, they shouldn't suffer from the associated limitations.  Under
some circumstances it might make sense for a raw_notifier callout routine
to unregister itself from the notifier chain.  This patch (as678) changes
the notifier core to allow for such things.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/kernel/sys.c b/kernel/sys.c
index 90930b28d2ca..7e0927bad713 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -137,14 +137,15 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
 		unsigned long val, void *v)
 {
 	int ret = NOTIFY_DONE;
-	struct notifier_block *nb;
+	struct notifier_block *nb, *next_nb;
 
 	nb = rcu_dereference(*nl);
 	while (nb) {
+		next_nb = rcu_dereference(nb->next);
 		ret = nb->notifier_call(nb, val, v);
 		if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
 			break;
-		nb = rcu_dereference(nb->next);
+		nb = next_nb;
 	}
 	return ret;
 }