netdev - [PATCH net-next 3/3] udp: only use paged allocation with scatter-gather

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Date:   Mon, 14 May 2018 19:07:47 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net-next 3/3] udp: only use paged allocation with scatter-gather

From: Willem de Bruijn <willemb@...gle.com>

Paged allocation stores most payload in skb frags. This helps udp gso
by avoiding copying from the gso skb to segment skb in skb_segment.

But without scatter-gather, data must be linear, so do not use paged
mode unless NETIF_F_SG.

Fixes: 15e36f5b8e98 ("udp: paged allocation with gso")
Reported-by: Sean Tranchetti <stranche@...eaurora.org>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 net/ipv4/ip_output.c  | 2 +-
 net/ipv6/ip6_output.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b5e21eb198d8..b38731d8a44f 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -884,7 +884,7 @@ static int __ip_append_data(struct sock *sk,
 
 	exthdrlen = !skb ? rt->dst.header_len : 0;
 	mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
-	paged = !!cork->gso_size;
+	paged = cork->gso_size && (rt->dst.dev->features & NETIF_F_SG);
 
 	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
 	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7f4493080df6..35a940b9f208 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1262,7 +1262,7 @@ static int __ip6_append_data(struct sock *sk,
 		dst_exthdrlen = rt->dst.header_len - rt->rt6i_nfheader_len;
 	}
 
-	paged = !!cork->gso_size;
+	paged = cork->gso_size && (rt->dst.dev->features & NETIF_F_SG);
 	mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize;
 	orig_mtu = mtu;
 
-- 
2.17.0.441.gb46fe60e1d-goog