From: Mark Rutland <mark.rutland@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Christopher Lameter <cl@linux.com>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Peter Zijlstra <peterz@infradead.org>,
Pranith Kumar <bobby.prani@gmail.com>,
linux-arch@vger.kernel.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH] percpu: make this_cpu_generic_read() atomic w.r.t. interrupts
Date: Wed, 27 Sep 2017 11:10:19 +0100 [thread overview]
Message-ID: <20170927101019.GB32150@leverpostej> (raw)
In-Reply-To: <alpine.DEB.2.20.1709271058030.4773@nanos>
On Wed, Sep 27, 2017 at 11:01:13AM +0200, Thomas Gleixner wrote:
> The default for 32bit architectures is that they CANNOT do atomic
> fetch/write of 8 bytes.
Indeed.
In addition, even the native word size accesses weren't guaranteed to be
atomic, as we hadn't used the appropriate accessors to prevent the
compiler from messing with things behind our backs.
> So instead of forcing that to be implemented in every affected
> architecture this wants to be addressed in generic code and those few
> 32bit architectures which can do atomic double word fetch/write
> implement the magic functions to do so.
I've done this in v2 [1], which Tejun has queued [2] as a fix for v4.14.
Thanks,
Mark.
[1] https://lkml.kernel.org/r/1506426112-19826-1-git-send-email-mark.rutland@arm.com
[2] https://lkml.kernel.org/r/20170926144118.GA70381@devbig577.frc2.facebook.com
next prev parent reply other threads:[~2017-09-27 10:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 13:24 [PATCH] percpu: make this_cpu_generic_read() atomic w.r.t. interrupts Mark Rutland
2017-09-25 15:18 ` Tejun Heo
2017-09-25 15:33 ` Mark Rutland
2017-09-25 15:44 ` Tejun Heo
2017-09-26 6:47 ` Christopher Lameter
2017-09-26 7:47 ` Thomas Gleixner
2017-09-26 16:42 ` Christopher Lameter
2017-09-27 9:01 ` Thomas Gleixner
2017-09-27 10:10 ` Mark Rutland [this message]
2017-09-26 17:28 ` Mark Rutland
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