linux-kernel - Re: [PATCH v5 0/8] Add generic support for relaxed atomics

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Date:	Fri, 7 Aug 2015 17:29:27 +0100
From:	Will Deacon <will.deacon@....com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"Waiman.Long@...com" <Waiman.Long@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"paulmck@...ux.vnet.ibm.com" <paulmck@...ux.vnet.ibm.com>,
	"mingo@...nel.org" <mingo@...nel.org>
Subject: Re: [PATCH v5 0/8] Add generic support for relaxed atomics

On Fri, Aug 07, 2015 at 04:13:03PM +0100, Peter Zijlstra wrote:
> On Thu, Aug 06, 2015 at 05:54:36PM +0100, Will Deacon wrote:
> > The series adds support for a family of relaxed atomics to the kernel.
> > More specifically:
> > 
> >   - acquire/release/relaxed flavours of xchg, cmpxchg and {add,sub}_return
> >   - atomic_read_acquire
> >   - atomic_set_release
> > 
> > This came out of a separate patch series porting the (barrier-heavy)
> > qrwlock code to arm64. Rather than have arch-specific hooks littered
> > around the place, it makes more sense to define a core set of relaxed
> > atomics that can be used regardless of architecture.
> > 
> > Changes since v4 are:
> > 
> >   * Drop the ret_t macro parameter in favour of typeof tricks (Peter Z)
> > 
> >   * Add a missing acquire to the qrwlock code, as it was based on a
> >     previous patch that I posted (Waiman Long)
> > 
> > Build tested on ARM, arm64, PowerPC and x86.
> 
> Queued it. There was a wee conflict with the atomic_{and,or,xor} bits
> for the ARM patch, but that was quickly sorted.

Great, thanks Peter! I'll port arm64 over for 4.4 (there's way too much
fun being had in asm/atomic.h right now).

> Does we want a Documentation/ update to reflect all this shiny new
> stuff?

Possibly. atomic_ops or memory-barriers?

Will
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