linux-kernel - Re: [PATCH 5/5] task_work: use TIF_NOTIFY

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Message-ID: <874kmuaw13.fsf@nanos.tec.linutronix.de>
Date:   Fri, 16 Oct 2020 20:03:04 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Jens Axboe <axboe@...nel.dk>, Oleg Nesterov <oleg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        peterz@...radead.org, Roman Gershman <romger@...zon.com>
Subject: Re: [PATCH 5/5] task_work: use TIF_NOTIFY_SIGNAL if available

On Fri, Oct 16 2020 at 08:53, Jens Axboe wrote:
> On 10/16/20 8:51 AM, Oleg Nesterov wrote:
>> On 10/16, Thomas Gleixner wrote:
>>>
>>> With moving the handling into get_signal() you don't need more changes
>>> to arch/* than adding the TIF bit, right?
>> 
>> we still need to do something like
>> 
>> 	-	if (thread_flags & _TIF_SIGPENDING)
>> 	+	if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
>> 			do_signal(...);
>> 
>> and add _TIF_NOTIFY_SIGNAL to the WORK-PENDING mask in arch/* code.
>
> Yes, but it becomes really minimal at that point, and just that. There's
> no touching any of the arch do_signal() code.
>
> Just finished the update of the branch to this model, and it does simplify
> things quite a bit! Most arch patches are now exactly just what you write
> above, no more.

Except for all the nasty ones which have these checks in ASM :)