From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, mingo@kernel.org,
torvalds@linux-foundation.org, mark.rutland@arm.com,
linux-arch@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
Alexander Kuleshov <kuleshovmail@gmail.com>,
dvyukov@google.com
Subject: Re: [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends()
Date: Wed, 11 Oct 2017 09:50:04 -0700 [thread overview]
Message-ID: <20171011165004.GA14318@linux.vnet.ibm.com> (raw)
In-Reply-To: <20171011161220.zqkdhynxerrcmvdd@hirez.programming.kicks-ass.net>
On Wed, Oct 11, 2017 at 06:12:20PM +0200, Peter Zijlstra wrote:
> On Wed, Oct 11, 2017 at 08:59:48AM -0700, Paul E. McKenney wrote:
> > On Wed, Oct 11, 2017 at 04:17:25PM +0100, David Howells wrote:
> > > I will, however, quibble with the appropriateness of the name READ_ONCE()...
> > > I still think it's not sufficiently obvious that this is a barrier and the
> > > barrier is after. Maybe READ_AND_BARRIER()?
> >
> > Linus was unhappy with READ_ONCE_CTRL() to tag control dependencies, but
> > indicated that he might consider it if it helped code-analysis tools.
> > Adding Dmitry Vyukov for his thoughts on whether tagging READ_ONCE()
> > for dependencies would help. Me, I would suggest READ_ONCE_DEP(), but
> > let's figure out if the bikeshed needs to be painted before arguing over
> > the color. ;-)
>
> Count me one vote for the READ_ONCE() name. This is about dependent
> reads, which are nothing special on anything except Alpha.
Agreed, unless specially marking them makes it easier for tools to
find bugs. In which case, we should definitely specially mark them.
Thanx, Paul
next prev parent reply other threads:[~2017-10-11 16:50 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-10 0:19 [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 01/15] doc: READ_ONCE() now implies smp_barrier_depends() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 02/15] mn10300: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 03/15] drivers/net/ethernet/qlogic/qed: Fix __qed_spq_block() ordering Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 04/15] fs/dcache: Use release-acquire for name/length update Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 05/15] percpu: READ_ONCE() now implies smp_read_barrier_depends() Paul E. McKenney
2017-10-10 14:08 ` Tejun Heo
2017-10-10 15:30 ` Paul E. McKenney
2017-10-10 15:49 ` Tejun Heo
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 06/15] rcu: Adjust read-side accessor comments for READ_ONCE() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 07/15] rtnetlink: Update now-misleading smp_read_barrier_depends() comment Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 08/15] seqlock: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 09/15] uprobes: " Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 10/15] locking: Remove smp_read_barrier_depends() from queued_spin_lock_slowpath() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 11/15] tracepoint: Remove smp_read_barrier_depends() from comment Paul E. McKenney
2017-10-10 0:31 ` Steven Rostedt
2017-10-10 1:12 ` Mathieu Desnoyers
2017-10-10 15:32 ` Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() Paul E. McKenney
2017-10-10 8:39 ` Peter Zijlstra
2017-10-10 9:36 ` David Howells
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 13/15] mm/ksm: Remove now-redundant smp_read_barrier_depends() Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 14/15] netfilter: " Paul E. McKenney
2017-10-10 8:43 ` Peter Zijlstra
2017-10-10 15:56 ` Paul E. McKenney
2017-10-10 0:22 ` [PATCH RFC tip/core/rcu 15/15] keyring: " Paul E. McKenney
2017-10-10 9:35 ` [PATCH RFC tip/core/rcu 12/15] lib/assoc_array: Remove smp_read_barrier_depends() David Howells
2017-10-10 15:50 ` Paul E. McKenney
2017-10-10 15:54 ` Peter Zijlstra
2017-10-10 16:05 ` Paul E. McKenney
2017-10-11 12:19 ` David Howells
2017-10-11 12:22 ` Will Deacon
2017-10-11 12:54 ` Paul E. McKenney
2017-10-11 14:18 ` Will Deacon
2017-10-11 14:50 ` Paul E. McKenney
2017-10-11 12:58 ` Paul E. McKenney
2017-10-11 15:17 ` David Howells
2017-10-11 15:59 ` Paul E. McKenney
2017-10-11 16:12 ` Peter Zijlstra
2017-10-11 16:24 ` Peter Zijlstra
2017-10-11 16:47 ` Paul E. McKenney
2017-10-11 16:54 ` Peter Zijlstra
2017-10-11 17:06 ` Paul E. McKenney
2017-10-11 17:11 ` Peter Zijlstra
2017-10-11 17:34 ` Paul E. McKenney
2017-10-11 18:43 ` Dmitry Vyukov
2017-10-11 18:56 ` Linus Torvalds
2017-10-11 19:28 ` Paul E. McKenney
2017-10-11 19:59 ` Dmitry Vyukov
2017-10-11 17:14 ` Paul E. McKenney
2017-10-11 17:19 ` Mark Rutland
2017-10-11 16:50 ` Paul E. McKenney [this message]
2017-10-11 16:07 ` David Howells
2017-10-11 16:17 ` Peter Zijlstra
2017-10-11 16:19 ` Paul E. McKenney
2017-10-11 15:28 ` David Howells
2017-10-11 16:02 ` Paul E. McKenney
2017-10-10 9:59 ` David Howells
2017-10-10 15:52 ` Paul E. McKenney
2017-10-11 12:21 ` [PATCH RFC tip/core/rcu 0/15] Remove to-be-unneeded smp_read_barrier_depends() David Howells
2017-10-11 12:56 ` Paul E. McKenney
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