Messages in this thread | | | Date | Tue, 15 Mar 2022 20:17:06 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH net-next 3/3] net: ipgre: add skb drop reasons to gre_rcv() |
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On Mon, 14 Mar 2022 21:33:12 +0800 menglong8.dong@gmail.com wrote: > From: Menglong Dong <imagedong@tencent.com> > > Replace kfree_skb() used in gre_rcv() with kfree_skb_reason(). With > previous patch, we can tell that no tunnel device is found when > PACKET_NEXT is returned by erspan_rcv() or ipgre_rcv(). > > In this commit, following new drop reasons are added: > > SKB_DROP_REASON_GRE_CSUM > SKB_DROP_REASON_GRE_NOTUNNEL > > Reviewed-by: Hao Peng <flyingpeng@tencent.com> > Reviewed-by: Biao Jiang <benbjiang@tencent.com> > Signed-off-by: Menglong Dong <imagedong@tencent.com> > --- > include/linux/skbuff.h | 2 ++ > include/trace/events/skb.h | 2 ++ > net/ipv4/ip_gre.c | 28 ++++++++++++++++++---------- > 3 files changed, 22 insertions(+), 10 deletions(-) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 5edb704af5bb..4f5e58e717ee 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -448,6 +448,8 @@ enum skb_drop_reason { > SKB_DROP_REASON_GRE_NOHANDLER, /* no handler found (version not > * supported?) > */ > + SKB_DROP_REASON_GRE_CSUM, /* GRE csum error */ > + SKB_DROP_REASON_GRE_NOTUNNEL, /* no tunnel device found */ > SKB_DROP_REASON_MAX, > }; > > diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h > index f2bcffdc4bae..e8f95c96cf9d 100644 > --- a/include/trace/events/skb.h > +++ b/include/trace/events/skb.h > @@ -63,6 +63,8 @@ > EM(SKB_DROP_REASON_TAP_TXFILTER, TAP_TXFILTER) \ > EM(SKB_DROP_REASON_GRE_VERSION, GRE_VERSION) \ > EM(SKB_DROP_REASON_GRE_NOHANDLER, GRE_NOHANDLER) \ > + EM(SKB_DROP_REASON_GRE_CSUM, GRE_CSUM) \ > + EM(SKB_DROP_REASON_GRE_NOTUNNEL, GRE_NOTUNNEL) \ > EMe(SKB_DROP_REASON_MAX, MAX) > > #undef EM > diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c > index b1579d8374fd..b989239e4abc 100644 > --- a/net/ipv4/ip_gre.c > +++ b/net/ipv4/ip_gre.c > @@ -421,9 +421,10 @@ static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi, > > static int gre_rcv(struct sk_buff *skb) > { > + enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; > struct tnl_ptk_info tpi; > bool csum_err = false; > - int hdr_len; > + int hdr_len, ret; > > #ifdef CONFIG_NET_IPGRE_BROADCAST > if (ipv4_is_multicast(ip_hdr(skb)->daddr)) { > @@ -438,19 +439,26 @@ static int gre_rcv(struct sk_buff *skb)
I feel like gre_parse_header() is a good candidate for converting to return a reason instead of errno.
> goto drop; > > if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) || > - tpi.proto == htons(ETH_P_ERSPAN2))) { > - if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD) > - return 0; > - goto out; > - } > + tpi.proto == htons(ETH_P_ERSPAN2))) > + ret = erspan_rcv(skb, &tpi, hdr_len); > + else > + ret = ipgre_rcv(skb, &tpi, hdr_len);
ipgre_rcv() OTOH may be better off taking the reason as an output argument. Assuming PACKET_REJECT means NOMEM is a little fragile.
> > - if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD) > + switch (ret) { > + case PACKET_NEXT: > + reason = SKB_DROP_REASON_GRE_NOTUNNEL; > + break; > + case PACKET_RCVD: > return 0; > - > -out: > + case PACKET_REJECT: > + reason = SKB_DROP_REASON_NOMEM; > + break; > + } > icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); > drop: > - kfree_skb(skb); > + if (csum_err) > + reason = SKB_DROP_REASON_GRE_CSUM; > + kfree_skb_reason(skb, reason); > return 0; > } >
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