linux-kernel - Re: [PATCH 3/5] kernel: add support for TIF_NOTIFY

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Message-ID: <87r1pzv8hy.fsf@nanos.tec.linutronix.de>
Date:   Thu, 15 Oct 2020 17:01:13 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Oleg Nesterov <oleg@...hat.com>, Jens Axboe <axboe@...nel.dk>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        peterz@...radead.org
Subject: Re: [PATCH 3/5] kernel: add support for TIF_NOTIFY_SIGNAL

On Thu, Oct 15 2020 at 16:37, Oleg Nesterov wrote:
> On 10/15, Jens Axboe wrote:
>> On 10/15/20 8:31 AM, Oleg Nesterov wrote:
>> > I don't understand why does this version requires CONFIG_GENERIC_ENTRY.
>> > 
>> > Afaics, it is very easy to change all the non-x86 arches to support
>> > TIF_NOTIFY_SIGNAL, but it is not trivial to change them all to use
>> > kernel/entry/common.c ?
>> 
>> I think that Thomas wants to gate TIF_NOTIFY_SIGNAL on conversion to
>> the generic entry code?
>
> Then I think TIF_NOTIFY_SIGNAL will be never fully supported ;)

Yeah, we proliferate crap on that basis forever. _ALL_ architectures
have the very same entry/exit ordering problems (or subsets and
different ones) which we fixed on x86.

So no, we don't want to have 24 different variants of the same thing
again. That's what common code is for.

Not doing that is making the life of everyone working on core
infrastructure pointlessly harder. Architecture people still have enough
ways to screw everyone up.

Thanks,

        tglx