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

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Message-ID: <1a89eacd-830e-7310-0e56-9b4b389cdc5d@kernel.dk>
Date:   Fri, 16 Oct 2020 08:53:53 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Oleg Nesterov <oleg@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
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 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.

-- 
Jens Axboe