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From: Tejun Heo <tj@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	Paul McKenney <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH] seqlock: fix raw_read_seqcount_latch()
Date: Wed, 25 May 2016 15:57:45 -0400	[thread overview]
Message-ID: <20160525195745.GH3354@mtj.duckdns.org> (raw)
In-Reply-To: <20160523093618.GG15728@worktop.ger.corp.intel.com>

Hello,

On Mon, May 23, 2016 at 11:36:18AM +0200, Peter Zijlstra wrote:
> > 	include/linux/percpu-refcount.h:146:36: warning: initialization makes pointer from integer without a cast [-Wint-conversion]
> > 	  percpu_ptr = lockless_dereference(ref->percpu_count_ptr);
> 
> TJ; would you prefer casting or not using lockless_dereference() here?

Casting is nasty - *(unsigned long __percpu **)& - because the macro
expects an lvalue.  I think it'd be better to revert to opencoding
READ_ONCE() and barrier there.  It's a pretty special case anyway.

Thanks.

-- 
tejun

  reply	other threads:[~2016-05-25 19:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-21 20:14 [PATCH] seqlock: fix raw_read_seqcount_latch() Alexey Dobriyan
2016-05-22 10:48 ` Peter Zijlstra
2016-05-22 18:50   ` Alexey Dobriyan
2016-05-23  9:36     ` Peter Zijlstra
2016-05-25 19:57       ` Tejun Heo [this message]
2016-05-25 20:11         ` [PATCH] percpu: Revert ("percpu: Replace smp_read_barrier_depends() with lockless_dereference()") Tejun Heo
2016-06-03 10:58   ` [tip:locking/core] locking/barriers: Validate lockless_dereference() is used on a pointer type tip-bot for Peter Zijlstra
2016-06-06 21:31     ` Mateusz Guzik
2016-06-07  7:10       ` Peter Zijlstra
2016-06-08 14:19   ` tip-bot for Peter Zijlstra
2016-05-27 11:11 ` [PATCH] seqlock: fix raw_read_seqcount_latch() Peter Zijlstra
2016-06-03 10:46   ` [tip:locking/core] locking/seqcount: Re-fix raw_read_seqcount_latch() tip-bot for Peter Zijlstra

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