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Date: Sat, 29 Apr 2017 13:21:33 -0700
From: Tom Herbert <tom@...bertland.com>
To: Davide Caratti <dcaratti@...hat.com>
Cc: Alexander Duyck <alexander.duyck@...il.com>,
David Laight <David.Laight@...lab.com>,
"David S . Miller" <davem@...emloft.net>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>,
"linux-sctp @ vger . kernel . org" <linux-sctp@...r.kernel.org>
Subject: Re: [PATCH RFC net-next v4 3/7] sk_buff: remove support for csum_bad
in sk_buff
On Thu, Apr 20, 2017 at 6:38 AM, Davide Caratti <dcaratti@...hat.com> wrote:
> This bit was introduced with 5a21232983aa ("net: Support for csum_bad in
> skbuff") to reduce the stack workload when processing RX packets carrying
> a wrong Internet Checksum. Up to now, only one driver (besides GRO core)
> are setting it.
> The test on NAPI_GRO_CB(skb)->flush in dev_gro_receive() is now done
> before the test on same_flow, to preserve behavior in case of wrong
> checksum.
>
> Suggested-by: Tom Herbert <tom@...bertland.com>
> Signed-off-by: Davide Caratti <dcaratti@...hat.com>
> ---
> drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 2 +-
> include/linux/netdevice.h | 4 +---
> include/linux/skbuff.h | 23 ++---------------------
> net/bridge/netfilter/nft_reject_bridge.c | 5 +----
> net/core/dev.c | 8 +++-----
> net/ipv4/netfilter/nf_reject_ipv4.c | 2 +-
> net/ipv6/netfilter/nf_reject_ipv6.c | 3 ---
> 7 files changed, 9 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
> index 3a8a4aa..9a08179 100644
> --- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
> +++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
> @@ -223,7 +223,7 @@ int aq_ring_rx_clean(struct aq_ring_s *self, int *work_done, int budget)
> skb->protocol = eth_type_trans(skb, ndev);
> if (unlikely(buff->is_cso_err)) {
> ++self->stats.rx.errors;
> - __skb_mark_checksum_bad(skb);
> + skb->ip_summed = CHECKSUM_NONE;
> } else {
> if (buff->is_ip_cso) {
> __skb_incr_checksum_unnecessary(skb);
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index bf84a67..ab9e3dc 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -2546,9 +2546,7 @@ static inline void skb_gro_incr_csum_unnecessary(struct sk_buff *skb)
> if (__skb_gro_checksum_validate_needed(skb, zero_okay, check)) \
> __ret = __skb_gro_checksum_validate_complete(skb, \
> compute_pseudo(skb, proto)); \
> - if (__ret) \
> - __skb_mark_checksum_bad(skb); \
> - else \
> + if (!__ret) \
> skb_gro_incr_csum_unnecessary(skb); \
> __ret; \
> })
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index ec4551b..927309e 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -743,7 +743,7 @@ struct sk_buff {
> __u8 csum_valid:1;
> __u8 csum_complete_sw:1;
> __u8 csum_level:2;
> - __u8 csum_bad:1;
> + __u8 __csum_bad_unused:1; /* one bit hole */
>
> __u8 dst_pending_confirm:1;
> #ifdef CONFIG_IPV6_NDISC_NODETYPE
> @@ -3387,21 +3387,6 @@ static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb)
> }
> }
>
> -static inline void __skb_mark_checksum_bad(struct sk_buff *skb)
> -{
> - /* Mark current checksum as bad (typically called from GRO
> - * path). In the case that ip_summed is CHECKSUM_NONE
> - * this must be the first checksum encountered in the packet.
> - * When ip_summed is CHECKSUM_UNNECESSARY, this is the first
> - * checksum after the last one validated. For UDP, a zero
> - * checksum can not be marked as bad.
> - */
> -
> - if (skb->ip_summed == CHECKSUM_NONE ||
> - skb->ip_summed == CHECKSUM_UNNECESSARY)
> - skb->csum_bad = 1;
> -}
> -
> /* Check if we need to perform checksum complete validation.
> *
> * Returns true if checksum complete is needed, false otherwise
> @@ -3455,9 +3440,6 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
> skb->csum_valid = 1;
> return 0;
> }
> - } else if (skb->csum_bad) {
> - /* ip_summed == CHECKSUM_NONE in this case */
> - return (__force __sum16)1;
> }
>
> skb->csum = psum;
> @@ -3517,8 +3499,7 @@ static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
>
> static inline bool __skb_checksum_convert_check(struct sk_buff *skb)
> {
> - return (skb->ip_summed == CHECKSUM_NONE &&
> - skb->csum_valid && !skb->csum_bad);
> + return (skb->ip_summed == CHECKSUM_NONE && skb->csum_valid);
> }
>
> static inline void __skb_checksum_convert(struct sk_buff *skb,
> diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c
> index 346ef6b..c16dd3a 100644
> --- a/net/bridge/netfilter/nft_reject_bridge.c
> +++ b/net/bridge/netfilter/nft_reject_bridge.c
> @@ -111,7 +111,7 @@ static void nft_reject_br_send_v4_unreach(struct net *net,
> __wsum csum;
> u8 proto;
>
> - if (oldskb->csum_bad || !nft_bridge_iphdr_validate(oldskb))
> + if (!nft_bridge_iphdr_validate(oldskb))
> return;
>
> /* IP header checks: fragment. */
> @@ -226,9 +226,6 @@ static bool reject6_br_csum_ok(struct sk_buff *skb, int hook)
> __be16 fo;
> u8 proto = ip6h->nexthdr;
>
> - if (skb->csum_bad)
> - return false;
> -
> if (skb_csum_unnecessary(skb))
> return true;
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index c7aec95..77a2d73 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4533,9 +4533,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
> if (!(skb->dev->features & NETIF_F_GRO))
> goto normal;
>
> - if (skb->csum_bad)
> - goto normal;
> -
> gro_list_prepare(napi, skb);
>
> rcu_read_lock();
> @@ -4595,11 +4592,12 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
> napi->gro_count--;
> }
>
> + if (NAPI_GRO_CB(skb)->flush)
> + goto normal;
> +
> if (same_flow)
> goto ok;
>
> - if (NAPI_GRO_CB(skb)->flush)
> - goto normal;
>
> if (unlikely(napi->gro_count >= MAX_GRO_SKBS)) {
> struct sk_buff *nskb = napi->gro_list;
> diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
> index 7cd8d0d..6f8d9e5 100644
> --- a/net/ipv4/netfilter/nf_reject_ipv4.c
> +++ b/net/ipv4/netfilter/nf_reject_ipv4.c
> @@ -172,7 +172,7 @@ void nf_send_unreach(struct sk_buff *skb_in, int code, int hook)
> struct iphdr *iph = ip_hdr(skb_in);
> u8 proto;
>
> - if (skb_in->csum_bad || iph->frag_off & htons(IP_OFFSET))
> + if (iph->frag_off & htons(IP_OFFSET))
> return;
>
> if (skb_csum_unnecessary(skb_in)) {
> diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
> index eedee5d..f63b18e 100644
> --- a/net/ipv6/netfilter/nf_reject_ipv6.c
> +++ b/net/ipv6/netfilter/nf_reject_ipv6.c
> @@ -220,9 +220,6 @@ static bool reject6_csum_ok(struct sk_buff *skb, int hook)
> __be16 fo;
> u8 proto;
>
> - if (skb->csum_bad)
> - return false;
> -
> if (skb_csum_unnecessary(skb))
> return true;
>
> --
> 2.7.4
>
Acked-by: Tom Herbert <tom@...bertland.com>
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