linux-kernel - Re: [PATCH 2/2] tty/sysrq: Add configurable handler to execute a compound action

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Date:   Mon, 17 Aug 2020 15:32:05 +0200
From:   Andrzej Pietrasiewicz <andrzej.p@...labora.com>
To:     Jiri Slaby <jirislaby@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, kernel@...labora.com
Subject: Re: [PATCH 2/2] tty/sysrq: Add configurable handler to execute a
 compound action

Hi Jiri,

W dniu 12.08.2020 o 13:45, Jiri Slaby pisze:
> On 04. 08. 20, 18:24, Andrzej Pietrasiewicz wrote:
>> Userland might want to execute e.g. 'w' (show blocked tasks), followed
>> by 's' (sync), followed by 1000 ms delay and then followed by 'c' (crash)
>> upon a single magic SysRq. Or one might want to execute the famous "Raising
>> Elephants Is So Utterly Boring" action. This patch adds a configurable
>> handler, triggered with 'C', for this exact purpose. The user specifies the
>> composition of the compound action using syntax similar to getopt, where
>> each letter corresponds to an individual action and a colon followed by a
>> number corresponds to a delay of that many milliseconds, e.g.:
>>
>> ws:1000c
>>
>> or
>>
>> r:100eis:1000ub
> 
> I think I miss what's that good for, given I can do it one-by-one
> without setting such strings anywhere (I usually want to do different
> things on different kinds of crashes)?
> 

The "REISUB" action is a common way of handling a bad situation, though,
so having a shortcut for a common way is helpful, yet we are not forcing
this particular action to happen when the 'C' sysrq is invoked and offer
configurability instead.

I addressed the comments you had with regard to the code in a v2 series.

Regards,

Andrzej