Re: [PATCH v6 0/8] Add vhost-user support to passt (part 2)

12 Jun 2024


      On Wed, 12 Jun 2024 19:37:44 +0200
Stefano Brivio  wrote:
...
On Wed, 12 Jun 2024 19:16:17 +0200
Stefano Brivio  wrote:
...
On Wed, 12 Jun 2024 17:47:26 +0200
Laurent Vivier  wrote:
...
Extract buffers management code from tcp.c and move
it to tcp_buf.c
tcp.c keeps all the generic code and will be also used by
the vhost-user functions.
Also compare mode to MODE_PASTA, as we will manage vhost-user
mode (MODE_VU) like MODE_PASST.
Something in this series breaks the pasta_podman/bats test, number 19
in that script (Single TCP port forwarding, IPv4, tap). I'm bisecting
now...
$ git bisect good
3c6a20486425ed00ba5b631bea11135045794dc2 is the first bad commit
commit 3c6a20486425ed00ba5b631bea11135045794dc2
Author: Laurent Vivier 
Date:   Wed Jun 12 17:47:34 2024 +0200
tap: use in->buf_size rather than sizeof(pkt_buf)
buf_size is set to sizeof(pkt_buf) by default. And it seems more correct
    to provide the actual size of the buffer.
Later a buf_size of 0 will allow vhost-user mode to detect
    guest memory buffers.
Signed-off-by: Laurent Vivier 
    Reviewed-by: David Gibson 
    Signed-off-by: Stefano Brivio 
tap.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
...checking that patch now.
Ouch, sorry, bad bisect, I forgot to rebuild at every step. The actual
issue seems to be in 1/8 (details as a reply to that one):

$ git bisect bad
fa462103eb219dfb8e6fe7bb25d1707d8a82b2a2 is the first bad commit
commit fa462103eb219dfb8e6fe7bb25d1707d8a82b2a2
Author: Laurent Vivier 
Date:   Wed Jun 12 17:47:27 2024 +0200

    tcp: extract buffer management from tcp_send_flag()
    
    This commit isolates the internal data structure management used for storing
    data (e.g., tcp4_l2_flags_iov[], tcp6_l2_flags_iov[], tcp4_flags_ip[],
    tcp4_flags[], ...) from the tcp_send_flag() function. The extracted
    functionality is relocated to a new function named tcp_fill_flag_header().
    
    tcp_fill_flag_header() is now a generic function that accepts parameters such
    as struct tcphdr and a data pointer. tcp_send_flag() utilizes this parameter to
    pass memory pointers from tcp4_l2_flags_iov[] and tcp6_l2_flags_iov[].
    
    This separation sets the stage for utilizing tcp_fill_flag_header() to
    set the memory provided by the guest via vhost-user in future developments.
    
    Signed-off-by: Laurent Vivier 
    Signed-off-by: Stefano Brivio 

 tcp.c | 72 ++++++++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 48 insertions(+), 24 deletions(-)

-- 
Stefano