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
next prev parent 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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