From: Thibaut VARENE <T-Bone@parisc-linux.org>
Date: Thu, 15 Mar 2007 11:59:19 +0000 (+0100)
Subject: make elv_register() output atomic
X-Git-Tag: v2.6.21-rc6~89^2~3
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=1ffb96c587fa2af0d690dc3548a4a781c477bfb7;p=linux-2.6-omap-h63xx.git

make elv_register() output atomic

Booting 2.6.21-rc3-g45592145 I noticed the following on one of my
machines in the bootlog:

io scheduler noop registered<6>Time: jiffies clocksource has been installed.

io scheduler deadline registered (default)

Looking at block/elevator.c, it appears that elv_register() uses two
consecutive printks in a non-atomic way, leading to the above glitch. The
attached trivial patch fixes this issue, by using a single printk.

Signed-off-by: Thibaut VARENE <varenet@parisc-linux.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/block/elevator.c b/block/elevator.c
index 25f6ef28e3b..96a00c82274 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -964,17 +964,18 @@ void elv_unregister_queue(struct request_queue *q)
 
 int elv_register(struct elevator_type *e)
 {
+	char *def = "";
 	spin_lock_irq(&elv_list_lock);
 	BUG_ON(elevator_find(e->elevator_name));
 	list_add_tail(&e->list, &elv_list);
 	spin_unlock_irq(&elv_list_lock);
 
-	printk(KERN_INFO "io scheduler %s registered", e->elevator_name);
 	if (!strcmp(e->elevator_name, chosen_elevator) ||
 			(!*chosen_elevator &&
 			 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
-				printk(" (default)");
-	printk("\n");
+				def = " (default)";
+
+	printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name, def);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(elv_register);