From: Jesse Gross <jesse@nicira.com>
Date: Sat, 4 Dec 2010 23:17:56 +0000 (-0800)
Subject: brcompat: Simplify generation of bridge ID.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6d6266e6c9e387052e34f8434ee1d80690bff75d;p=openvswitch

brcompat: Simplify generation of bridge ID.

Currently we use a fairly complicated method of generating the
bridge ID, since the actual struct is only available in a header
file private to the Linux bridge.  The current method appears to
be correct but is difficult to reason about.  This replaces it
with a simple memcpy, which is more analogous to what the Linux
bridge does.

Flagged by sparse.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
---

diff --git a/datapath/brcompat.c b/datapath/brcompat.c
index 2113eae0..f23db93c 100644
--- a/datapath/brcompat.c
+++ b/datapath/brcompat.c
@@ -224,14 +224,13 @@ static int brc_get_bridge_info(struct net_device *dev,
 			       struct __bridge_info __user *ub)
 {
 	struct __bridge_info b;
-	u64 id = 0;
-	int i;
 
 	memset(&b, 0, sizeof(struct __bridge_info));
 
-	for (i=0; i<ETH_ALEN; i++)
-		id |= (u64)dev->dev_addr[i] << (8*(ETH_ALEN-1 - i));
-	b.bridge_id = cpu_to_be64(id);
+	/* First two bytes are the priority, which we should skip.  This comes
+	 * from struct bridge_id in br_private.h, which is unavailable to us.
+	 */
+	memcpy((u8 *)&b.bridge_id + 2, dev->dev_addr, ETH_ALEN);
 	b.stp_enabled = 0;
 
 	if (copy_to_user(ub, &b, sizeof(struct __bridge_info)))