Re: [PATCH iproute2] ss: show extra info when '--processes' is not used

[Stephen Hemminger <stephen@networkplumber.org>]

On Sat, 13 Jan 2024 18:10:21 +0100
"Matthieu Baerts (NGI0)" <matttbe@kernel.org> wrote:

> A recent modification broke "extra" options for all protocols showing
> info about the processes when '-p' / '--processes' option was not used
> as well. In other words, all the additional bits displayed at the end or
> at the next line were no longer printed if the user didn't ask to show
> info about processes as well.
> 
> The reason is that, the "current_field" pointer never switched to the
> "Ext" column. If the user didn't ask to display the processes, nothing
> happened when trying to print extra bits using the "out()" function,
> because the current field was still pointing to the "Process" one, now
> marked as disabled.
> 
> Before the commit mentioned below, it was not an issue not to switch to
> the "Ext" or "Process" columns because they were never marked as
> "disabled".
> 
> Here is a quick list of options that were no longer displayed if '-p' /
> '--processes' was not set:
> 
> - AF_INET(6):
>   -o, --options
>   -e, --extended
>   --tos
>   --cgroup
>   --inet-sockopt
>   -m, --memory
>   -i, --info
> 
> - AF_PACKET:
>   -e, --extended
> 
> - AF_XDP:
>   -e, --extended
> 
> - AF_UNIX:
>   -m, --memory
>   -e, --extended
> 
> - TIPC:
>   --tipcinfo
> 
> That was just by quickly reading the code, I probably missed some. But
> this shows that the impact can be quite important for all scripts using
> 'ss' to monitor connections or to report info.
> 
> Fixes: 1607bf53 ("ss: prevent "Process" column from being printed unless requested")
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
> ---

This needs more review and testing before being merged.
"once burned, twice shy"