From: Peter Zijlstra <peterz@infradead.org>
To: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nick Piggin <npiggin@kernel.dk>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [RFC] page-table walkers vs memory order
Date: Thu, 26 Jul 2012 22:39:29 +0200 [thread overview]
Message-ID: <1343335169.32120.18.camel@twins> (raw)
In-Reply-To: <alpine.LSU.2.00.1207241356350.2094@eggly.anvils>
On Tue, 2012-07-24 at 14:51 -0700, Hugh Dickins wrote:
> I do love the status quo, but an audit would be welcome. When
> it comes to patches, personally I tend to prefer ACCESS_ONCE() and
> smp_read_barrier_depends() and accompanying comments to be hidden away
> in the underlying macros or inlines where reasonable, rather than
> repeated all over; but I may have my priorities wrong on that.
>
>
Yeah, I was being lazy, and I totally forgot to actually look at the
alpha code.
How about we do a generic (cribbed from rcu_dereference):
#define page_table_deref(p) \
({ \
typeof(*p) *______p = (typeof(*p) __force *)ACCESS_ONCE(p);\
smp_read_barrier_depends(); \
((typeof(*p) __force __kernel *)(______p)); \
})
and use that all over to dereference page-tables. That way all this
lives in one place. Granted, I'll have to go edit all arch code, but I
seem to be doing that on a frequent basis anyway :/
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next prev parent reply other threads:[~2012-07-26 20:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-23 17:34 [RFC] page-table walkers vs memory order Peter Zijlstra
2012-07-23 19:27 ` Paul E. McKenney
2012-07-24 21:51 ` Hugh Dickins
2012-07-25 17:56 ` Paul E. McKenney
2012-07-25 20:26 ` Hugh Dickins
2012-07-25 21:12 ` Paul E. McKenney
2012-07-25 22:09 ` Hugh Dickins
2012-07-25 22:37 ` Paul E. McKenney
2012-07-26 8:11 ` Peter Zijlstra
2012-07-30 19:21 ` Jamie Lokier
2012-07-30 20:28 ` Paul E. McKenney
2012-07-26 20:39 ` Peter Zijlstra [this message]
2012-07-27 19:22 ` Hugh Dickins
2012-07-27 19:39 ` Paul E. McKenney
2012-08-04 14:37 ` Andrea Arcangeli
2012-08-04 22:02 ` Paul E. McKenney
2012-08-04 22:47 ` Andrea Arcangeli
2012-08-04 22:59 ` Dr. David Alan Gilbert
2012-08-04 23:11 ` Paul E. McKenney
2012-08-05 0:10 ` Dr. David Alan Gilbert
2012-08-04 23:06 ` Paul E. McKenney
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