| Message ID | 20210825210117.1668371-1-ntspring@fb.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net-next,v3] tcp: enable mid stream window clamp | expand |
On Wed, Aug 25, 2021 at 2:02 PM Neil Spring <ntspring@fb.com> wrote: > > The TCP_WINDOW_CLAMP socket option is defined in tcp(7) to "Bound the size > of the advertised window to this value." Window clamping is distributed > across two variables, window_clamp ("Maximal window to advertise" in > tcp.h) and rcv_ssthresh ("Current window clamp"). > > This patch updates the function where the window clamp is set to also > reduce the current window clamp, rcv_sshthresh, if needed. With this, > setting the TCP_WINDOW_CLAMP option has the documented effect of limiting > the window. This patch looks like a bug-fix so it should be applied to net not net-next? > > Signed-off-by: Neil Spring <ntspring@fb.com> > --- > v2: - fix email formatting > > v3: - address comments by setting rcv_ssthresh based on prior window > > net/ipv4/tcp.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index f931def6302e..e8b48df73c85 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -3338,6 +3338,7 @@ int tcp_set_window_clamp(struct sock *sk, int val) > } else { > tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ? > SOCK_MIN_RCVBUF / 2 : val; > + tp->rcv_ssthresh = min(tp->rcv_wnd, tp->window_clamp); > } > return 0; > } > -- > 2.30.2 >
On Thu, Aug 26, 2021 at 12:11 PM Yuchung Cheng <ycheng@google.com> wrote: > > On Wed, Aug 25, 2021 at 2:02 PM Neil Spring <ntspring@fb.com> wrote: > > > > The TCP_WINDOW_CLAMP socket option is defined in tcp(7) to "Bound the size > > of the advertised window to this value." Window clamping is distributed > > across two variables, window_clamp ("Maximal window to advertise" in > > tcp.h) and rcv_ssthresh ("Current window clamp"). > > > > This patch updates the function where the window clamp is set to also > > reduce the current window clamp, rcv_sshthresh, if needed. With this, > > setting the TCP_WINDOW_CLAMP option has the documented effect of limiting > > the window. > This patch looks like a bug-fix so it should be applied to net not net-next? It seems TCP_WINDOW_CLAMP never worked in this context, not sure if any application was expecting it to work. Note that if we target net tree, we would like a Fixes: tag. I will give my SOB a bit later in the day, I have to run some errands. Thanks.
On 8/25/21 2:01 PM, Neil Spring wrote: > The TCP_WINDOW_CLAMP socket option is defined in tcp(7) to "Bound the size > of the advertised window to this value." Window clamping is distributed > across two variables, window_clamp ("Maximal window to advertise" in > tcp.h) and rcv_ssthresh ("Current window clamp"). > > This patch updates the function where the window clamp is set to also > reduce the current window clamp, rcv_sshthresh, if needed. With this, > setting the TCP_WINDOW_CLAMP option has the documented effect of limiting > the window. > > Signed-off-by: Neil Spring <ntspring@fb.com> > --- > v2: - fix email formatting > > v3: - address comments by setting rcv_ssthresh based on prior window > SGTM, thanks. Signed-off-by: Eric Dumazet <edumazet@google.com>
Hello: This patch was applied to netdev/net-next.git (refs/heads/master): On Wed, 25 Aug 2021 14:01:17 -0700 you wrote: > The TCP_WINDOW_CLAMP socket option is defined in tcp(7) to "Bound the size > of the advertised window to this value." Window clamping is distributed > across two variables, window_clamp ("Maximal window to advertise" in > tcp.h) and rcv_ssthresh ("Current window clamp"). > > This patch updates the function where the window clamp is set to also > reduce the current window clamp, rcv_sshthresh, if needed. With this, > setting the TCP_WINDOW_CLAMP option has the documented effect of limiting > the window. > > [...] Here is the summary with links: - [net-next,v3] tcp: enable mid stream window clamp https://git.kernel.org/netdev/net-next/c/3aa7857fe1d7 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f931def6302e..e8b48df73c85 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3338,6 +3338,7 @@ int tcp_set_window_clamp(struct sock *sk, int val) } else { tp->window_clamp = val < SOCK_MIN_RCVBUF / 2 ? SOCK_MIN_RCVBUF / 2 : val; + tp->rcv_ssthresh = min(tp->rcv_wnd, tp->window_clamp); } return 0; }
The TCP_WINDOW_CLAMP socket option is defined in tcp(7) to "Bound the size of the advertised window to this value." Window clamping is distributed across two variables, window_clamp ("Maximal window to advertise" in tcp.h) and rcv_ssthresh ("Current window clamp"). This patch updates the function where the window clamp is set to also reduce the current window clamp, rcv_sshthresh, if needed. With this, setting the TCP_WINDOW_CLAMP option has the documented effect of limiting the window. Signed-off-by: Neil Spring <ntspring@fb.com> --- v2: - fix email formatting v3: - address comments by setting rcv_ssthresh based on prior window net/ipv4/tcp.c | 1 + 1 file changed, 1 insertion(+)