[ovs-dev] [PATCH 13/19] brcompat: Simplify generation of bridge ID.

Jesse Gross jesse at nicira.com
Thu Dec 9 06:14:11 UTC 2010


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 at nicira.com>
---
 datapath/brcompat.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/datapath/brcompat.c b/datapath/brcompat.c
index 2113eae..f23db93 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)))
-- 
1.7.1





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