[PATCH 1/1] Elevator init fixes

[PATCH 1/1] Elevator init fixes

[Zachary Amsden]

I got a panic in the elevator code, backtrace :

Unable to handle kernel NULL pointer dereference at virtual address 00000060
..
EIP is at elevator_put+0x0/0x30 (null elevator_type passed)
..
elevator_init+0x38
blk_init_queu_node+0xc9
floppy_init+0xdb
do_initcalls+0x23
init+0x10a
init+0x0

Clearly if the kmalloc here fails, e->elevator_type is not yet set; this
appears to be the correct fix, but I think I probably hit the second case
due to a race condition.  Someone more familiar with the elevator code
should look at this more closely until I can determine if I can reproduce.

Signed-off-by: Zachary Amsden <zach@vmware.com>

Index: linux-2.6.14-zach-work/drivers/block/elevator.c
===================================================================
--- linux-2.6.14-zach-work.orig/drivers/block/elevator.c	2005-11-07 09:41:11.000000000 -0800
+++ linux-2.6.14-zach-work/drivers/block/elevator.c	2005-11-07 15:57:10.000000000 -0800
@@ -190,14 +190,14 @@ int elevator_init(request_queue_t *q, ch
 
 	eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL);
 	if (!eq) {
-		elevator_put(e->elevator_type);
+		elevator_put(e);
 		return -ENOMEM;
 	}
 
 	ret = elevator_attach(q, e, eq);
 	if (ret) {
 		kfree(eq);
-		elevator_put(e->elevator_type);
+		elevator_put(e);
 	}
 
 	return ret;