linux-kernel - [PATCH 10/14] skbuff: drop zero check from skb_zcopy

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Message-Id: <d9a6ae91295e88f15d73b42823f1d67906bc52ab.1641863490.git.asml.silence@gmail.com>
Date:   Tue, 11 Jan 2022 01:21:43 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     netdev@...r.kernel.org, "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        linux-kernel@...r.kernel.org,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [PATCH 10/14] skbuff: drop zero check from skb_zcopy_set

Only two skb_zcopy_set() callers may pass a NULL skb, so kill the zero
check from inside the function, which can't be compiled out, and place
it where needed. It's also needed by the following patch.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 include/linux/skbuff.h | 2 +-
 net/ipv4/ip_output.c   | 3 ++-
 net/ipv6/ip6_output.c  | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 642acb0d1646..8a7d0d03a100 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1499,7 +1499,7 @@ static inline void skb_zcopy_init(struct sk_buff *skb, struct ubuf_info *uarg)
 static inline void skb_zcopy_set(struct sk_buff *skb, struct ubuf_info *uarg,
 				 bool *have_ref)
 {
-	if (skb && uarg && !skb_zcopy(skb)) {
+	if (uarg && !skb_zcopy(skb)) {
 		if (unlikely(have_ref && *have_ref))
 			*have_ref = false;
 		else
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 57c1d8431386..87d4472545a5 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1010,7 +1010,8 @@ static int __ip_append_data(struct sock *sk,
 			paged = true;
 		} else {
 			uarg->zerocopy = 0;
-			skb_zcopy_set(skb, uarg, &extra_uref);
+			if (skb)
+				skb_zcopy_set(skb, uarg, &extra_uref);
 		}
 	}
 
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 6a7bba4dd04d..9881b61da493 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1522,7 +1522,8 @@ static int __ip6_append_data(struct sock *sk,
 			paged = true;
 		} else {
 			uarg->zerocopy = 0;
-			skb_zcopy_set(skb, uarg, &extra_uref);
+			if (skb)
+				skb_zcopy_set(skb, uarg, &extra_uref);
 		}
 	}
 
-- 
2.34.1