From: Linus Torvalds <torvalds@g5.osdl.org>
Date: Sun, 15 Jan 2006 06:08:28 +0000 (-0800)
Subject: x86: Work around compiler code generation bug with -Os
X-Git-Tag: v2.6.16-rc1~104
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=caf5b04c82f05c65843b2d7189845d6c3df5a41e;p=linux-2.6

x86: Work around compiler code generation bug with -Os

Some versions of gcc generate incorrect code for the inet_check_attr()
function, apparently due to a totally bogus index -> pointer comparison
transformation.

At least "gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)" from FC4 is
affected, possibly others too.

This changes the function subtly so that the buggy gcc transformation
doesn't trigger.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 5b25fc0d98..4e3d3811de 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -289,13 +289,13 @@ static int inet_check_attr(struct rtmsg *r, struct rtattr **rta)
 {
 	int i;
 
-	for (i=1; i<=RTA_MAX; i++) {
-		struct rtattr *attr = rta[i-1];
+	for (i=1; i<=RTA_MAX; i++, rta++) {
+		struct rtattr *attr = *rta;
 		if (attr) {
 			if (RTA_PAYLOAD(attr) < 4)
 				return -EINVAL;
 			if (i != RTA_MULTIPATH && i != RTA_METRICS)
-				rta[i-1] = (struct rtattr*)RTA_DATA(attr);
+				*rta = (struct rtattr*)RTA_DATA(attr);
 		}
 	}
 	return 0;