On Tue, Nov 1, 2016 at 1:53 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > From: Eric Dumazet <eduma...@google.com> > > As Ilya Lesokhin suggested, we can collapse two skbs at retransmit > time even if the skb at the right has fragments. > > We simply have to use more generic skb_copy_bits() instead of > skb_copy_from_linear_data() in tcp_collapse_retrans() > > Also need to guard this skb_copy_bits() in case there is nothing to > copy, otherwise skb_put() could panic if left skb has frags. > > Tested: > > Used following packetdrill test > > // Establish a connection. > 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 > +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 > +0 bind(3, ..., ...) = 0 > +0 listen(3, 1) = 0 > > +0 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 8> > +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> > +.100 < . 1:1(0) ack 1 win 257 > +0 accept(3, ..., ...) = 4 > > +0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 > +0 write(4, ..., 200) = 200 > +0 > P. 1:201(200) ack 1 > +.001 write(4, ..., 200) = 200 > +0 > P. 201:401(200) ack 1 > +.001 write(4, ..., 200) = 200 > +0 > P. 401:601(200) ack 1 > +.001 write(4, ..., 200) = 200 > +0 > P. 601:801(200) ack 1 > +.001 write(4, ..., 200) = 200 > +0 > P. 801:1001(200) ack 1 > +.001 write(4, ..., 100) = 100 > +0 > P. 1001:1101(100) ack 1 > +.001 write(4, ..., 100) = 100 > +0 > P. 1101:1201(100) ack 1 > +.001 write(4, ..., 100) = 100 > +0 > P. 1201:1301(100) ack 1 > +.001 write(4, ..., 100) = 100 > +0 > P. 1301:1401(100) ack 1 > > +.100 < . 1:1(0) ack 1 win 257 <nop,nop,sack 1001:1401> > // Check that TCP collapse works : > +0 > P. 1:1001(1000) ack 1 > > > Reported-by: Ilya Lesokhin <il...@mellanox.com> > Signed-off-by: Eric Dumazet <eduma...@google.com> > Cc: Neal Cardwell <ncardw...@google.com> > Cc: Yuchung Cheng <ych...@google.com> > Cc: Ilpo Järvinen <ilpo.jarvi...@helsinki.fi> > ---
Acked-by: Neal Cardwell <ncardw...@google.com> Thanks, Eric. :-) neal
