From ad405857b174ed31a97982bb129c320d03321cf5 Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Thu, 26 Apr 2018 13:42:18 -0400 Subject: [PATCH] udp: better wmem accounting on gso skb_segment by default transfers allocated wmem from the gso skb to the tail of the segment list. This underreports real truesize of the list, especially if the tail might be dropped. Similar to tcp_gso_segment, update wmem_alloc with the aggregate list truesize and make each segment responsible for its own share by setting skb->destructor. Clear gso_skb->destructor prior to calling skb_segment to skip the default assignment to tail. Signed-off-by: Willem de Bruijn Signed-off-by: David S. Miller --- net/ipv4/udp_offload.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 6c2b7640f6f3..dc5158cba66e 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -191,6 +191,8 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, netdev_features_t features, unsigned int mss, __sum16 check) { + struct sock *sk = gso_skb->sk; + unsigned int sum_truesize = 0; struct sk_buff *segs, *seg; unsigned int hdrlen; struct udphdr *uh; @@ -201,9 +203,15 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, hdrlen = gso_skb->data - skb_mac_header(gso_skb); skb_pull(gso_skb, sizeof(*uh)); + /* clear destructor to avoid skb_segment assigning it to tail */ + WARN_ON_ONCE(gso_skb->destructor != sock_wfree); + gso_skb->destructor = NULL; + segs = skb_segment(gso_skb, features); - if (unlikely(IS_ERR_OR_NULL(segs))) + if (unlikely(IS_ERR_OR_NULL(segs))) { + gso_skb->destructor = sock_wfree; return segs; + } for (seg = segs; seg; seg = seg->next) { uh = udp_hdr(seg); @@ -214,8 +222,14 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, if (!seg->next) csum_replace2(&uh->check, htons(mss), htons(seg->len - hdrlen - sizeof(*uh))); + + seg->destructor = sock_wfree; + seg->sk = sk; + sum_truesize += seg->truesize; } + refcount_add(sum_truesize - gso_skb->truesize, &sk->sk_wmem_alloc); + return segs; } EXPORT_SYMBOL_GPL(__udp_gso_segment); -- 2.30.2