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Re: [PATCH ipvs-next] ipvs: avoid indirect calls when calculating checks

To: Julian Anastasov <ja@xxxxxx>
Subject: Re: [PATCH ipvs-next] ipvs: avoid indirect calls when calculating checksums
Cc: Matteo Croce <mcroce@xxxxxxxxxx>, lvs-devel@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, netfilter-devel@xxxxxxxxxxxxxxx, coreteam@xxxxxxxxxxxxx, Wensong Zhang <wensong@xxxxxxxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Wed, 23 Jan 2019 13:50:56 +0100
On Sun, Jan 20, 2019 at 02:11:31PM +0200, Julian Anastasov wrote:
> 
>       Hello,
> 
> On Sat, 19 Jan 2019, Matteo Croce wrote:
> 
> > The function pointer ip_vs_protocol->csum_check is only used in protocol
> > specific code, and never in the generic one.
> > Remove the function pointer from struct ip_vs_protocol and call the
> > checksum functions directly.
> > This reduces the performance impact of the Spectre mitigation, and
> > should give a small improvement even with RETPOLINES disabled.
> > 
> > Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
> 
>       Looks good to me, thanks!
> 
> Acked-by: Julian Anastasov <ja@xxxxxx>

Likewise, Pablo could you consider applying this to nf-next?

Acked-by: Simon Horman <horms@xxxxxxxxxxxx>

> 
> > ---
> >  include/net/ip_vs.h                     |  3 ---
> >  net/netfilter/ipvs/ip_vs_proto_ah_esp.c |  2 --
> >  net/netfilter/ipvs/ip_vs_proto_sctp.c   |  8 +++++---
> >  net/netfilter/ipvs/ip_vs_proto_tcp.c    | 12 +++++++-----
> >  net/netfilter/ipvs/ip_vs_proto_udp.c    | 12 +++++++-----
> >  5 files changed, 19 insertions(+), 18 deletions(-)
> > 
> > diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> > index a0d2e0bb9a94..047f9a5ccaad 100644
> > --- a/include/net/ip_vs.h
> > +++ b/include/net/ip_vs.h
> > @@ -453,9 +453,6 @@ struct ip_vs_protocol {
> >     int (*dnat_handler)(struct sk_buff *skb, struct ip_vs_protocol *pp,
> >                         struct ip_vs_conn *cp, struct ip_vs_iphdr *iph);
> >  
> > -   int (*csum_check)(int af, struct sk_buff *skb,
> > -                     struct ip_vs_protocol *pp);
> > -
> >     const char *(*state_name)(int state);
> >  
> >     void (*state_transition)(struct ip_vs_conn *cp, int direction,
> > diff --git a/net/netfilter/ipvs/ip_vs_proto_ah_esp.c 
> > b/net/netfilter/ipvs/ip_vs_proto_ah_esp.c
> > index 5320d39976e1..480598cb0f05 100644
> > --- a/net/netfilter/ipvs/ip_vs_proto_ah_esp.c
> > +++ b/net/netfilter/ipvs/ip_vs_proto_ah_esp.c
> > @@ -129,7 +129,6 @@ struct ip_vs_protocol ip_vs_protocol_ah = {
> >     .conn_out_get =         ah_esp_conn_out_get,
> >     .snat_handler =         NULL,
> >     .dnat_handler =         NULL,
> > -   .csum_check =           NULL,
> >     .state_transition =     NULL,
> >     .register_app =         NULL,
> >     .unregister_app =       NULL,
> > @@ -152,7 +151,6 @@ struct ip_vs_protocol ip_vs_protocol_esp = {
> >     .conn_out_get =         ah_esp_conn_out_get,
> >     .snat_handler =         NULL,
> >     .dnat_handler =         NULL,
> > -   .csum_check =           NULL,
> >     .state_transition =     NULL,
> >     .register_app =         NULL,
> >     .unregister_app =       NULL,
> > diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c 
> > b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> > index b0cd7d08f2a7..bc3d1625ecc8 100644
> > --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> > +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> > @@ -9,6 +9,9 @@
> >  #include <net/sctp/checksum.h>
> >  #include <net/ip_vs.h>
> >  
> > +static int
> > +sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
> > +
> >  static int
> >  sctp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
> >                struct ip_vs_proto_data *pd,
> > @@ -105,7 +108,7 @@ sctp_snat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!sctp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /* Call application helper if needed */
> > @@ -152,7 +155,7 @@ sctp_dnat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!sctp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /* Call application helper if needed */
> > @@ -587,7 +590,6 @@ struct ip_vs_protocol ip_vs_protocol_sctp = {
> >     .conn_out_get   = ip_vs_conn_out_get_proto,
> >     .snat_handler   = sctp_snat_handler,
> >     .dnat_handler   = sctp_dnat_handler,
> > -   .csum_check     = sctp_csum_check,
> >     .state_name     = sctp_state_name,
> >     .state_transition = sctp_state_transition,
> >     .app_conn_bind  = sctp_app_conn_bind,
> > diff --git a/net/netfilter/ipvs/ip_vs_proto_tcp.c 
> > b/net/netfilter/ipvs/ip_vs_proto_tcp.c
> > index 1770fc6ce960..6a275f989085 100644
> > --- a/net/netfilter/ipvs/ip_vs_proto_tcp.c
> > +++ b/net/netfilter/ipvs/ip_vs_proto_tcp.c
> > @@ -31,6 +31,9 @@
> >  
> >  #include <net/ip_vs.h>
> >  
> > +static int
> > +tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
> > +
> >  static int
> >  tcp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
> >               struct ip_vs_proto_data *pd,
> > @@ -166,7 +169,7 @@ tcp_snat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!tcp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /* Call application helper if needed */
> > @@ -192,7 +195,7 @@ tcp_snat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             tcp_fast_csum_update(cp->af, tcph, &cp->daddr, &cp->vaddr,
> >                                  cp->dport, cp->vport);
> >             if (skb->ip_summed == CHECKSUM_COMPLETE)
> > -                   skb->ip_summed = (cp->app && pp->csum_check) ?
> > +                   skb->ip_summed = cp->app ?
> >                                      CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
> >     } else {
> >             /* full checksum calculation */
> > @@ -244,7 +247,7 @@ tcp_dnat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!tcp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /*
> > @@ -275,7 +278,7 @@ tcp_dnat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             tcp_fast_csum_update(cp->af, tcph, &cp->vaddr, &cp->daddr,
> >                                  cp->vport, cp->dport);
> >             if (skb->ip_summed == CHECKSUM_COMPLETE)
> > -                   skb->ip_summed = (cp->app && pp->csum_check) ?
> > +                   skb->ip_summed = cp->app ?
> >                                      CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
> >     } else {
> >             /* full checksum calculation */
> > @@ -736,7 +739,6 @@ struct ip_vs_protocol ip_vs_protocol_tcp = {
> >     .conn_out_get =         ip_vs_conn_out_get_proto,
> >     .snat_handler =         tcp_snat_handler,
> >     .dnat_handler =         tcp_dnat_handler,
> > -   .csum_check =           tcp_csum_check,
> >     .state_name =           tcp_state_name,
> >     .state_transition =     tcp_state_transition,
> >     .app_conn_bind =        tcp_app_conn_bind,
> > diff --git a/net/netfilter/ipvs/ip_vs_proto_udp.c 
> > b/net/netfilter/ipvs/ip_vs_proto_udp.c
> > index 0f53c49025f8..3285718264d5 100644
> > --- a/net/netfilter/ipvs/ip_vs_proto_udp.c
> > +++ b/net/netfilter/ipvs/ip_vs_proto_udp.c
> > @@ -28,6 +28,9 @@
> >  #include <net/ip.h>
> >  #include <net/ip6_checksum.h>
> >  
> > +static int
> > +udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
> > +
> >  static int
> >  udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
> >               struct ip_vs_proto_data *pd,
> > @@ -156,7 +159,7 @@ udp_snat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!udp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /*
> > @@ -186,7 +189,7 @@ udp_snat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
> >                                  cp->dport, cp->vport);
> >             if (skb->ip_summed == CHECKSUM_COMPLETE)
> > -                   skb->ip_summed = (cp->app && pp->csum_check) ?
> > +                   skb->ip_summed = cp->app ?
> >                                      CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
> >     } else {
> >             /* full checksum calculation */
> > @@ -239,7 +242,7 @@ udp_dnat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             int ret;
> >  
> >             /* Some checks before mangling */
> > -           if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> > +           if (!udp_csum_check(cp->af, skb, pp))
> >                     return 0;
> >  
> >             /*
> > @@ -270,7 +273,7 @@ udp_dnat_handler(struct sk_buff *skb, struct 
> > ip_vs_protocol *pp,
> >             udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
> >                                  cp->vport, cp->dport);
> >             if (skb->ip_summed == CHECKSUM_COMPLETE)
> > -                   skb->ip_summed = (cp->app && pp->csum_check) ?
> > +                   skb->ip_summed = cp->app ?
> >                                      CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
> >     } else {
> >             /* full checksum calculation */
> > @@ -494,7 +497,6 @@ struct ip_vs_protocol ip_vs_protocol_udp = {
> >     .conn_out_get =         ip_vs_conn_out_get_proto,
> >     .snat_handler =         udp_snat_handler,
> >     .dnat_handler =         udp_dnat_handler,
> > -   .csum_check =           udp_csum_check,
> >     .state_transition =     udp_state_transition,
> >     .state_name =           udp_state_name,
> >     .register_app =         udp_register_app,
> > -- 
> > 2.20.1
> 
> Regards
> 
> --
> Julian Anastasov <ja@xxxxxx>
> 

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