| Message ID | 1256544393-12450-5-git-send-email-gilad@codefidence.com |
|---|---|
| State | Rejected, archived |
| Delegated to: | David Miller |
| Headers | show |
Gilad Ben-Yossef wrote: > Implement querying and acting upon the no sack bit in the features > field. > > Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> > Sigend-off-by: Ori Finkelman <ori@comsleep.com> > Sigend-off-by: Yony Amit <yony@comsleep.com> > Please explain how this code turns SACK on when it is off globally? As both Eric and I asked? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
William Allen Simpson wrote: > Gilad Ben-Yossef wrote: >> Implement querying and acting upon the no sack bit in the features >> field. >> >> Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> >> Sigend-off-by: Ori Finkelman <ori@comsleep.com> >> Sigend-off-by: Yony Amit <yony@comsleep.com> >> > Please explain how this code turns SACK on when it is off globally? > > As both Eric and I asked? It doesn't. Please see my discussion with Eric for the why. In short, doing so introduce a very subtle change to what the existing interface do today, which will break backwards compatibility by changing the meaning of writing zero to the relevant sysctl. I don't want to be hunt down by angry sys admins :-) Thanks, Gilad
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index adf2068..9c802a6 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -377,7 +377,7 @@ enum #define RTAX_MAX (__RTAX_MAX - 1) #define RTAX_FEATURE_ECN 0x00000001 -#define RTAX_FEATURE_SACK 0x00000002 +#define RTAX_FEATURE_NO_SACK 0x00000002 #define RTAX_FEATURE_TIMESTAMP 0x00000004 #define RTAX_FEATURE_ALLFRAG 0x00000008 diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index d502f49..b14f780 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3763,7 +3763,8 @@ void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx, break; case TCPOPT_SACK_PERM: if (opsize == TCPOLEN_SACK_PERM && th->syn && - !estab && sysctl_tcp_sack) { + !estab && sysctl_tcp_sack && + !dst_feature(dst, RTAX_FEATURE_NO_SACK)) { opt_rx->sack_ok = 1; tcp_sack_reset(opt_rx); } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index fcd278a..64db8dd 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -464,6 +464,7 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, struct tcp_md5sig_key **md5) { struct tcp_sock *tp = tcp_sk(sk); unsigned size = 0; + struct dst_entry *dst = __sk_dst_get(sk); #ifdef CONFIG_TCP_MD5SIG *md5 = tp->af_specific->md5_lookup(sk, sk); @@ -498,7 +499,8 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, opts->options |= OPTION_WSCALE; size += TCPOLEN_WSCALE_ALIGNED; } - if (likely(sysctl_tcp_sack)) { + if (likely(sysctl_tcp_sack && + !dst_feature(dst, RTAX_FEATURE_NO_SACK))) { opts->options |= OPTION_SACK_ADVERTISE; if (unlikely(!(OPTION_TS & opts->options))) size += TCPOLEN_SACKPERM_ALIGNED;
Implement querying and acting upon the no sack bit in the features field. Signed-off-by: Gilad Ben-Yossef <gilad@codefidence.com> Sigend-off-by: Ori Finkelman <ori@comsleep.com> Sigend-off-by: Yony Amit <yony@comsleep.com> --- include/linux/rtnetlink.h | 2 +- net/ipv4/tcp_input.c | 3 ++- net/ipv4/tcp_output.c | 4 +++- 3 files changed, 6 insertions(+), 3 deletions(-)