All of lore.kernel.org
 help / color / mirror / Atom feed
From: Alan Stern <stern@rowland.harvard.edu>
To: Will Deacon <will@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	parri.andrea@gmail.com, peterz@infradead.org,
	boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com,
	j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com,
	dlustig@nvidia.com, joel@joelfernandes.org,
	viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org
Subject: Re: Litmus test for question from Al Viro
Date: Mon, 5 Oct 2020 11:16:39 -0400	[thread overview]
Message-ID: <20201005151639.GE376584@rowland.harvard.edu> (raw)
In-Reply-To: <20201005151313.GA23892@willie-the-truck>

On Mon, Oct 05, 2020 at 04:13:13PM +0100, Will Deacon wrote:
> > The failure to recognize the dependency in P0 should be considered a 
> > combined limitation of the memory model and herd7.  It's not a simple 
> > mistake that can be fixed by a small rewrite of herd7; rather it's a 
> > deliberate choice we made based on herd7's inherent design.  We 
> > explicitly said that control dependencies extend only to the code in the 
> > branches of an "if" statement; anything beyond the end of the statement 
> > is not considered to be dependent.
> 
> Interesting. How does this interact with loops that are conditionally broken
> out of, e.g.  a relaxed cmpxchg() loop or an smp_cond_load_relaxed() call
> prior to a WRITE_ONCE()?

Heh --  We finesse this issue by not supporting loops at all!  :-)

Alan

  reply	other threads:[~2020-10-05 15:16 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01  4:51 Litmus test for question from Al Viro Paul E. McKenney
2020-10-01 16:15 ` Alan Stern
2020-10-01 16:36   ` Al Viro
2020-10-01 18:39     ` Alan Stern
2020-10-01 19:29       ` Al Viro
2020-10-01 21:30   ` Paul E. McKenney
2020-10-03  2:01     ` Alan Stern
2020-10-03 13:22     ` Alan Stern
2020-10-03 15:16       ` Akira Yokosawa
2020-10-03 17:13         ` Bug in herd7 [Was: Re: Litmus test for question from Al Viro] Alan Stern
2020-10-03 22:50           ` Akira Yokosawa
2020-10-04  1:40           ` [PATCH] tools: memory-model: Document that the LKMM can easily miss control dependencies Alan Stern
2020-10-04 21:07             ` joel
2020-10-04 23:12               ` Paul E. McKenney
2020-10-05 15:15           ` Bug in herd7 [Was: Re: Litmus test for question from Al Viro] Luc Maranget
2020-10-05 15:53             ` Alan Stern
2020-10-05 16:52               ` Paul E. McKenney
2020-10-05 18:19                 ` Alan Stern
2020-10-05 19:18                   ` Paul E. McKenney
2020-10-05 19:48                     ` Alan Stern
2020-10-06 16:39                       ` Paul E. McKenney
2020-10-06 17:05                         ` Alan Stern
2020-10-07 17:50                           ` Paul E. McKenney
2020-10-07 19:40                             ` Alan Stern
2020-10-07 22:38                               ` Paul E. McKenney
2020-10-08  2:25                                 ` Alan Stern
2020-10-08  2:50                                   ` Paul E. McKenney
2020-10-08 14:01                                     ` Alan Stern
2020-10-08 18:32                                       ` Paul E. McKenney
2020-10-05 15:54             ` Paul E. McKenney
2020-10-04 23:31       ` Litmus test for question from Al Viro Paul E. McKenney
2020-10-05  2:38         ` Alan Stern
2020-10-05  8:20           ` Will Deacon
2020-10-05  9:12             ` Will Deacon
2020-10-05 14:01               ` Paul E. McKenney
2020-10-05 14:23               ` Alan Stern
2020-10-05 15:13                 ` Will Deacon
2020-10-05 15:16                   ` Alan Stern [this message]
2020-10-05 15:35                     ` Peter Zijlstra
2020-10-05 15:49                       ` Paul E. McKenney
2020-10-05 14:16             ` Alan Stern
2020-10-05 14:03           ` Paul E. McKenney
2020-10-05 14:24             ` Alan Stern
2020-10-05 14:44             ` joel
2020-10-05 15:55               ` Paul E. McKenney
2020-10-05  8:36         ` David Laight
2020-10-05 13:59           ` Paul E. McKenney
2020-10-03 16:08     ` joel
2020-10-03 16:11       ` joel
2020-10-04 23:13         ` Paul E. McKenney
2020-10-03  2:35   ` Jon Masters
2020-10-04 23:32     ` Paul E. McKenney

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201005151639.GE376584@rowland.harvard.edu \
    --to=stern@rowland.harvard.edu \
    --cc=akiyks@gmail.com \
    --cc=boqun.feng@gmail.com \
    --cc=dhowells@redhat.com \
    --cc=dlustig@nvidia.com \
    --cc=j.alglave@ucl.ac.uk \
    --cc=joel@joelfernandes.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luc.maranget@inria.fr \
    --cc=npiggin@gmail.com \
    --cc=parri.andrea@gmail.com \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.