Re: [PATCH] cifs: add new debugging macro cifs_server_dbg

[ronnie sahlberg <ronniesahlberg@gmail.com>]

On Wed, Aug 28, 2019 at 8:05 PM Aurélien Aptel <aaptel@suse.com> wrote:
>
> Ronnie Sahlberg <lsahlber@redhat.com> writes:
> > which can be used from contexts where we have a TCP_Server_Info *server.
> > This new macro will prepend the debugging string with "Server:<servername> "
> > which will help when debugging issues on hosts with many cifs connections
> > to several different servers.
> >
> > Convert a bunch of callsites in connect.c from cifs_dbg to instead use
> > cifs_server_dbg.
>
> This looks like a poorman's ftrace. I'm not sure about it I think it
> would make more sense to add those (or convert) as ftrace tracepoints as
> it supports filtering built-in.

In a sense they are but the usecase is different.
Ftrace is way superior if you can handily reproduce an issue in a lab and test.
This is to make the dmesg output more meaningful for production scenarios where
running a long ftrace is not an option.


If there is an issue that takes days/weeks/.. to reproduce on a
production system
you can't run ftrace for that long.

This is for triage when you have rare events that can not (easily) be
reproduced on production
systems and when after the fact you only have dmesg to further aid in
how to proceed to triage an issue.


>
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> Aurélien Aptel / SUSE Labs Samba Team
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