From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"Waiman.Long@hp.com" <Waiman.Long@hp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic operations
Date: Tue, 14 Jul 2015 13:38:01 +0200 [thread overview]
Message-ID: <20150714113801.GK19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20150714113147.GF16213@arm.com>
On Tue, Jul 14, 2015 at 12:31:47PM +0100, Will Deacon wrote:
> #ifndef atomic_add
> #define atomic_add(args...) (void)atomic_add_return_relaxed(args);
>
> It would mean a new architecture only has to define a barrier instruction
> and a handful of relaxed atomics for a bare-minimum atomic.h avoiding
> spinlocks.
Look at include/asm-generic/atomic.h, all you need is a cmpxchg().
We could easily change that to be cmpxchg_relaxed() and a few barriers.
next prev parent reply other threads:[~2015-07-14 11:38 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 12:31 [PATCH 0/5] Add generic support for relaxed atomics Will Deacon
2015-07-13 12:31 ` [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic operations Will Deacon
2015-07-14 10:25 ` Peter Zijlstra
2015-07-14 10:32 ` Will Deacon
2015-07-14 10:58 ` Peter Zijlstra
2015-07-14 11:08 ` Will Deacon
2015-07-14 11:24 ` Peter Zijlstra
2015-07-14 11:31 ` Will Deacon
2015-07-14 11:38 ` Peter Zijlstra [this message]
2015-07-14 15:55 ` Will Deacon
2015-07-13 12:31 ` [PATCH 2/5] asm-generic: rework atomic-long.h to avoid bulk code duplication Will Deacon
2015-07-13 12:31 ` [PATCH 3/5] asm-generic: add relaxed/acquire/release variants for atomic_long_t Will Deacon
2015-07-13 12:31 ` [PATCH 4/5] lockref: remove homebrew cmpxchg64_relaxed macro definition Will Deacon
2015-07-13 12:31 ` [PATCH 5/5] locking/qrwlock: make use of acquire/release/relaxed atomics Will Deacon
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