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[PATCH] aoe: initialize locking structures before registering char devices

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From: Ed L. Cashin <ecashin@...>
To: <linux-kernel@...>
Cc: Andrew Morton <akpm@...>, Ed L. Cashin <ecashin@...>
Subject: [PATCH] aoe: initialize locking structures before registering char devices
Date: Wednesday, December 26, 2007 - 4:25 pm

This patch was made against 2.6.24-rc6-mm1.

In March 2007, Alexey Dobriyan suggested this change, which
eliminates a race after register_chardev has been called but
the locking primitives protecting the error messages ring
buffer have not yet been initialized.

The initialization could happen at compile time, but that
would leave aoe as the only user of __DECLARE_SEMAPHORE_GENERIC.

Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
---
 drivers/block/aoe/aoechr.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/aoe/aoechr.c b/drivers/block/aoe/aoechr.c
index e8e60e7..2620073 100644
--- a/drivers/block/aoe/aoechr.c
+++ b/drivers/block/aoe/aoechr.c
@@ -259,13 +259,13 @@ aoechr_init(void)
 {
 	int n, i;
 
+	sema_init(&emsgs_sema, 0);
+	spin_lock_init(&emsgs_lock);
 	n = register_chrdev(AOE_MAJOR, "aoechr", &aoe_fops);
 	if (n < 0) { 
 		printk(KERN_ERR "aoe: can't register char device\n");
 		return n;
 	}
-	sema_init(&emsgs_sema, 0);
-	spin_lock_init(&emsgs_lock);
 	aoe_class = class_create(THIS_MODULE, "aoe");
 	if (IS_ERR(aoe_class)) {
 		unregister_chrdev(AOE_MAJOR, "aoechr");
-- 
1.5.3.4

--
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Messages in current thread:
[PATCH 01/13] bring driver version number to 47, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 13/13] update copyright date, Ed L. Cashin, (Thu Dec 20, 6:16 pm)
Re: [PATCH 13/13] update copyright date, Andrew Morton, (Sat Dec 22, 2:03 am)
[PATCH 12/13] make error messages more specific, Ed L. Cashin, (Thu Dec 20, 6:16 pm)
[PATCH 11/13] the aoeminor doesn't need a long format, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 10/13] add module parameter for users who need more o..., Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 09/13] remove race between use and initialization of ..., Ed L. Cashin, (Thu Dec 20, 6:15 pm)
Re: [PATCH 09/13] remove race between use and initialization..., Andrew Morton, (Sat Dec 22, 2:00 am)
[PATCH] aoe: document the behavior of /dev/etherd/err, Ed L. Cashin, (Wed Dec 26, 4:35 pm)
[PATCH] aoe: initialize locking structures before registerin..., Ed L. Cashin, (Wed Dec 26, 4:25 pm)
Re: [PATCH 09/13] remove race between use and initialization..., Ed L. Cashin, (Wed Dec 26, 3:28 pm)
[PATCH 08/13] only install new AoE device once, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 07/13] dynamically allocate a capped number of skbs w..., Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 06/13] user can ask driver to forget previously detec..., Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 05/13] eliminate goto and improve readability, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 04/13] clean up udev configuration example, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 03/13] mac_addr: avoid 64-bit arch compiler warnings, Ed L. Cashin, (Thu Dec 20, 6:15 pm)
[PATCH 02/13] handle multiple network paths to AoE device, Ed L. Cashin, (Thu Dec 20, 6:15 pm)