Subject: Re: [PATCH net-next v2 12/14] tun/selftests: add RX truesize injection for TCP window tests

From: Jakub Kicinski <[email-masked]>
Date: Sat, 14 Mar 2026 18:18:39 -0700

On Sat, 14 Mar 2026 14:13:46 -0600 [email-masked] wrote:
> Add a test-only TUN ioctl that inflates RX skb->truesize, plus the
> packetdrill-side helper needed to drive that ioctl through packetdrill's
> own TUN queue file descriptor.
> 
> Use that plumbing to cover the receive-window regressions where
> scaling_ratio drifts after advertisement, alongside the baseline too-big
> packetdrill cases that exercise the same sender-visible rwnd accounting
> from the non-injected path.

You missed adding the tun program to the Makefile.

  tcp-rcv-neg-window-truesize-pkt                                               
  tcp-rcv-toobig-default-truesize-pkt                                           
  tcp-rcv-wnd-shrink-allowed-truesize-pkt                                       
                                                                               
Fail with:                                                            

  sh: line 1: ../tun: No such file or directory                                 
  tcp_rcv_*_truesize.pkt:*: error executing `../tun --set-rx-truesize tun0 6553\
6` command: non-zero status 127        

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