linux-kernel - Re: [PATCH v2 1/2] livepatch: Send a fake signal periodically

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Message-ID: <nycvar.YFH.7.76.1901162210090.6626@cbobk.fhfr.pm>
Date:   Wed, 16 Jan 2019 22:11:12 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Miroslav Benes <mbenes@...e.cz>
cc:     jpoimboe@...hat.com, jeyu@...nel.org, pmladek@...e.com,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] livepatch: Send a fake signal periodically

On Tue, 15 Jan 2019, Miroslav Benes wrote:

> An administrator may send a fake signal to all remaining blocking tasks
> of a running transition by writing to
> /sys/kernel/livepatch/<patch>/signal attribute. Let's do it
> automatically after 15 seconds. The timeout is chosen deliberately. It
> gives the tasks enough time to transition themselves.
> 
> Theoretically, sending it once should be more than enough. However,
> every task must get outside of a patched function to be successfully
> transitioned. It could prove not to be simple and resending could be
> helpful in that case.
> 
> A new workqueue job could be a cleaner solution to achieve it, but it
> could also introduce deadlocks and cause more headaches with
> synchronization and cancelling.
> 
> Signed-off-by: Miroslav Benes <mbenes@...e.cz>
[ ... snip ... ]
> @@ -400,6 +408,7 @@ void klp_try_complete_transition(void)
>  		 */
>  		schedule_delayed_work(&klp_transition_work,
>  				      round_jiffies_relative(HZ));
> +
>  		return;
>  	}

I somehow didn't like the newly added newline here :) so I've removed it, 
and applied both patches to for-5.1/fake-signal.

Thanks,

-- 
Jiri Kosina
SUSE Labs