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From:   Woody Lin <woodylin@google.com>
Date:   Thu, 26 Aug 2021 18:23:53 +0800
Message-ID: <CAHn4Deczc6gSSsxys6UeAMB99p1jHMZmLFj+KwZ2QhH7dx8E8w@mail.gmail.com>
Subject: Re: [PATCH] ANDROID: staging: add userpanic-dev driver
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Todd Kjos <tkjos@android.com>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <christian@brauner.io>,
        Hridya Valsaraju <hridya@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev
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On Thu, Aug 26, 2021 at 5:48 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Thu, Aug 26, 2021 at 05:28:54PM +0800, Woody Lin wrote:
> > Add char device driver 'userpanic-dev' that exposes an interface to
> > userspace processes to request a system panic with customized panic
> > message.
> >
> > Signed-off-by: Woody Lin <woodylin@google.com>
> > ---
> >  drivers/staging/android/Kconfig         |  12 +++
> >  drivers/staging/android/Makefile        |   1 +
> >  drivers/staging/android/userpanic-dev.c | 110 ++++++++++++++++++++++++
>
> Why is this in staging?  What is wrong with it that it can not just go
> into the real part of the kernel?  A TODO file is needed explaining what
> needs to be done here in order for it to be accepted.

Got it. No more TODO for this driver and I will move it to drivers/android/.

>
> But why is this really needed at all?  Why would userspace want to panic
> the kernel in yet-another-way?

The idea is to panic the kernel with a panic message specified by the userspace
process requesting the panic. Without this the panic handler can only collect
panic message "sysrq triggered crash" for a panic triggered by user processes.
Using this driver, user processes can put an informative description -
process name,
reason ...etc. - to the panic message.

>
> thanks,
>
> greg k-h

Regards,
Woody