netdev - [PATCH net-next v2] net/ipv6: silence 'passing zero to ERR

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Date:   Thu, 13 Apr 2023 10:10:05 +0000
From:   Haoyi Liu <iccccc@...t.edu.cn>
To:     "David S. Miller" <davem@...emloft.net>,
        David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     hust-os-kernel-patches@...glegroups.com, yalongz@...t.edu.cn,
        error27@...il.com, Haoyi Liu <iccccc@...t.edu.cn>,
        Dongliang Mu <dzm91@...t.edu.cn>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2] net/ipv6: silence 'passing zero to ERR_PTR()' warning

Smatch complains that if xfrm_lookup() returns NULL then this does a
weird thing with "err":

    net/ ipv6/ icmp.c:411 icmpv6_route_lookup()
    warn: passing zero to ERR_PTR()

Merge conditional paths and remove unnecessary 'else'. No functional
change.

Signed-off-by: Haoyi Liu <iccccc@...t.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@...t.edu.cn>
---
v1->v2: Remove unnecessary 'else'.
The issue is found by static analysis, and the patch is remains untested.
---
 net/ipv6/icmp.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 1f53f2a74480..a12eef11c7ee 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -393,17 +393,12 @@ static struct dst_entry *icmpv6_route_lookup(struct net *net,
 		goto relookup_failed;
 
 	dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP);
-	if (!IS_ERR(dst2)) {
-		dst_release(dst);
-		dst = dst2;
-	} else {
-		err = PTR_ERR(dst2);
-		if (err == -EPERM) {
-			dst_release(dst);
-			return dst2;
-		} else
-			goto relookup_failed;
-	}
+	err = PTR_ERR_OR_ZERO(dst2);
+	if (err && err != -EPERM)
+		goto relookup_failed;
+
+	dst_release(dst);
+	return dst2;	/* returns success or ERR_PTR(-EPERM) */
 
 relookup_failed:
 	if (dst)
-- 
2.40.0