commit d3b7f69de2b92e4b6057d81e6c52f629a8663368
author Jeff Dike <jdike@addtoit.com> Sat Feb 10 01:43:56 2007 -0800
committer Linus Torvalds <torvalds@woody.linux-foundation.org> Sun Feb 11 10:51:21 2007 -0800
tree ad2ba9ef0cf024b3341b5eaf67929ee82b71701b
parent 190c3e456325942a17785332fe15b68eeb3775ca

[PATCH] uml: add locking to network transport registration

The registration of host network transports needed some locking.  The
transport list itself is locked, but calls to the registration routines are
not.  This is compensated for by checking that a transport structure is not
yet on any list.

I also took the opportunity to const all fields in the transport structure
except the list, which obviously can be modified.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/drivers/net_kern.c

diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index 07e839e..b10154c 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -498,10 +498,8 @@
 	int index;
 };
 
-/* Filled in at boot time.  Will need locking if the transports become
- * modular.
- */
-struct list_head transports = LIST_HEAD_INIT(transports);
+static DEFINE_SPINLOCK(transports_lock);
+static LIST_HEAD(transports);
 
 /* Filled in during early boot */
 struct list_head eth_cmd_line = LIST_HEAD_INIT(eth_cmd_line);
@@ -540,7 +538,10 @@
 	char *mac = NULL;
 	int match;
 
+	spin_lock(&transports_lock);
+	BUG_ON(!list_empty(&new->list));
 	list_add(&new->list, &transports);
+	spin_unlock(&transports_lock);
 
 	list_for_each_safe(ele, next, &eth_cmd_line){
 		eth = list_entry(ele, struct eth_init, list);