linux-kernel - Re: [PATCH v4 1/2] livepatch: send a fake signal to all blocking tasks

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Message-ID: <87tvxabvsf.fsf@concordia.ellerman.id.au>
Date:   Fri, 01 Dec 2017 21:13:36 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Jiri Kosina <jikos@...nel.org>, Miroslav Benes <mbenes@...e.cz>
Cc:     jpoimboe@...hat.com, jeyu@...nel.org, pmladek@...e.com,
        lpechacek@...e.cz, pavel@....cz, live-patching@...r.kernel.org,
        linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v4 1/2] livepatch: send a fake signal to all blocking tasks

Jiri Kosina <jikos@...nel.org> writes:
> On Wed, 15 Nov 2017, Miroslav Benes wrote:
>> Live patching consistency model is of LEAVE_PATCHED_SET and
>> SWITCH_THREAD. This means that all tasks in the system have to be marked
>> one by one as safe to call a new patched function. Safe means when a
>> task is not (sleeping) in a set of patched functions. That is, no
>> patched function is on the task's stack. Another clearly safe place is
>> the boundary between kernel and userspace. The patching waits for all
>> tasks to get outside of the patched set or to cross the boundary. The
>> transition is completed afterwards.
...
>> 
>> Signed-off-by: Miroslav Benes <mbenes@...e.cz>
>> Cc: Oleg Nesterov <oleg@...hat.com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Ingo Molnar <mingo@...hat.com>
>> Cc: "H. Peter Anvin" <hpa@...or.com>
>> Cc: Andy Lutomirski <luto@...nel.org>
>> Cc: linuxppc-dev@...ts.ozlabs.org
>> Cc: x86@...nel.org
>> ---
>>  Documentation/ABI/testing/sysfs-kernel-livepatch | 12 +++++++
>>  Documentation/livepatch/livepatch.txt            | 11 +++++--
>>  arch/powerpc/kernel/signal.c                     |  6 ++--
>>  arch/x86/entry/common.c                          |  6 ++--
>>  kernel/livepatch/core.c                          | 30 +++++++++++++++++
>>  kernel/livepatch/transition.c                    | 41 ++++++++++++++++++++++++
>>  kernel/livepatch/transition.h                    |  1 +
>>  kernel/signal.c                                  |  4 ++-
>
> I'd like to be queuing this patchset for the next merge window, so if 
> there are any objections for the out-of-kernel/livepatch/* changes, please 
> speak up now.

The powerpc changes look innocuous and in-line with the change log, no
objection from me. Have an ack if you like:

Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)

cheers