linux-kernel - Re: [PATCH REBASED 3/6] s390: Add __down_read

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Message-Id: <20170930123612.0fb250fe@mschwideX1>
Date:   Sat, 30 Sep 2017 12:36:12 +0200
From:   Martin Schwidefsky <schwidefsky@...ibm.com>
To:     Heiko Carstens <heiko.carstens@...ibm.com>
Cc:     Kirill Tkhai <ktkhai@...tuozzo.com>, linux-ia64@...r.kernel.org,
        avagin@...tuozzo.com, peterz@...radead.org, hpa@...or.com,
        gorcunov@...tuozzo.com, linux-arch@...r.kernel.org,
        linux-s390@...r.kernel.org, x86@...nel.org, mingo@...hat.com,
        mattst88@...il.com, fenghua.yu@...el.com, arnd@...db.de,
        ink@...assic.park.msu.ru, tglx@...utronix.de, rth@...ddle.net,
        tony.luck@...el.com, linux-kernel@...r.kernel.org,
        linux-alpha@...r.kernel.org, davem@...emloft.net,
        rientjes@...gle.com, viro@...iv.linux.org.uk
Subject: Re: [PATCH REBASED 3/6] s390: Add __down_read_killable()

On Sat, 30 Sep 2017 11:20:02 +0200
Heiko Carstens <heiko.carstens@...ibm.com> wrote:

> On Fri, Sep 29, 2017 at 07:06:18PM +0300, Kirill Tkhai wrote:
> > Similar to __down_write_killable(), and read killable primitive.
> > 
> > Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com>
> > ---
> >  arch/s390/include/asm/rwsem.h |   18 ++++++++++++++++--
> >  1 file changed, 16 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/s390/include/asm/rwsem.h b/arch/s390/include/asm/rwsem.h  
> 
> FWIW, while looking into this patch I realized that we never optimized our
> rwsem primitives to make use of new atomic instructions.
> 
> The generic rwsem header file however does, since it uses atomic ops which
> we did optimize. Even when compiling for old machines the generic version
> generates better code. Therefore I will remove the 15 years old s390
> implementation and switch to the generic version instead.

Take care not to conflict with the queued spinlock/rwlock patches on the
features branch. 

https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git/commit/?h=features&id=eb3b7b848fb3dd00f7a57d633d4ae4d194aa7865

Me thinks that what you have in mind is already done.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.