netdev - Re: [PATCH net-next v2 4/4] tools: ynl: add --dbg-small-recv for easier kernel testing

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Message-ID: <m2a5ndhrb1.fsf@gmail.com>
Date: Tue, 05 Mar 2024 11:05:38 +0000
From: Donald Hunter <donald.hunter@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net,  netdev@...r.kernel.org,  edumazet@...gle.com,
  pabeni@...hat.com,  jiri@...nulli.us
Subject: Re: [PATCH net-next v2 4/4] tools: ynl: add --dbg-small-recv for
 easier kernel testing

Jakub Kicinski <kuba@...nel.org> writes:

> Most "production" netlink clients use large buffers to
> make dump efficient, which means that handling of dump
> continuation in the kernel is not very well tested.
>
> Add an option for debugging / testing handling of dumps.
> It enables printing of extra netlink-level debug and
> lowers the recv() buffer size in one go. When used
> without any argument (--dbg-small-recv) it picks
> a very small default (4000), explicit size can be set,
> too (--dbg-small-recv 5000).
>
> Example:
>
> $ ./cli.py [...] --dbg-small-recv
> Recv: read 3712 bytes, 29 messages
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
>  [...]
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
> Recv: read 3968 bytes, 31 messages
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
>  [...]
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
> Recv: read 532 bytes, 5 messages
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
>  [...]
>    nl_len = 128 (112) nl_flags = 0x0 nl_type = 19
>    nl_len = 20 (4) nl_flags = 0x2 nl_type = 3
>
> (the [...] are edits to shorten the commit message).
>
> Note that the first message of the dump is sized conservatively
> by the kernel.
>
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

Reviewed-by: Donald Hunter <donald.hunter@...il.com>