linux-kernel - Re: [PATCH V2 11/19] csky: Atomic operations

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Date:   Fri, 6 Jul 2018 22:06:59 +0800
From:   Guo Ren <ren_guo@...ky.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, daniel.lezcano@...aro.org,
        jason@...edaemon.net, arnd@...db.de, c-sky_gcc_upstream@...ky.com,
        gnu-csky@...tor.com, thomas.petazzoni@...tlin.com,
        wbx@...ibc-ng.org, green.hu@...il.com
Subject: Re: [PATCH V2 11/19] csky: Atomic operations

On Fri, Jul 06, 2018 at 02:03:23PM +0200, Peter Zijlstra wrote:
> > > Test-and-set with MB acting as ACQUIRE, ok.
> > Em ... Ok, I'll try to use test-and-set function instead of it.
> 
> "test-and-set" is just the name of this type of spinlock implementation.
> 
> You _could_ use the linux test_and_set bitop, but those are defined on
> unsigned long and spinlock_t is generally assumed to be of unsigned int
> size.
> 
> Go with the ticket locks as per below.
Ok, I'll learn it.

> > Ok, I'll try to implement ticket lock in next version patch.
> 
> If you need inspiration, look at:
> 
arch/arm/include/asm/spinlock.h
> 
> Or look at the current version of that file and ignore the LSE version.
> 
> Note that unlock is a store half-word (u16), not having seen your arch
> manual yet I don't know if you even have that.
Nice tips, thank you very much.

 Guo Ren