From: Alan Stern <stern@rowland.harvard.edu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Frederic Weisbecker <fweisbec@gmail.com>,
Fengguang Wu <fengguang.wu@intel.com>, LKP <lkp@01.org>,
LKML <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Andrea Parri <andrea.parri@amarulasolutions.com>,
Luc Maranget <luc.maranget@inria.fr>,
Jade Alglave <j.alglave@ucl.ac.uk>
Subject: Re: rcu_read_lock lost its compiler barrier
Date: Tue, 4 Jun 2019 13:00:03 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1906041251210.1731-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <CAHk-=wgGnCw==uY8radrB+Tg_CEmzOtwzyjfMkuh7JmqFh+jzQ@mail.gmail.com>
On Tue, 4 Jun 2019, Linus Torvalds wrote:
> So I don't technically disagree with anything you say,
That's good to know!
> I just wanted
> to point out that as far as the kernel is concerned, we do have higher
> quality expectations from the compiler than just "technically valid
> according to the C standard".
Which suggests asking whether these higher expectations should be
reflected in the Linux Kernel Memory Model. So far we have largely
avoided doing that sort of thing, although there are a few exceptions.
(For example, we assume the compiler does not destroy address
dependencies from volatile reads -- but we also warn that this
assumption may fail if the programmer does not follow some rules
described in one of Paul's documentation files.)
Alan
WARNING: multiple messages have this Message-ID (diff)
From: Alan Stern <stern@rowland.harvard.edu>
To: lkp@lists.01.org
Subject: Re: rcu_read_lock lost its compiler barrier
Date: Tue, 04 Jun 2019 13:00:03 -0400 [thread overview]
Message-ID: <Pine.LNX.4.44L0.1906041251210.1731-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <CAHk-=wgGnCw==uY8radrB+Tg_CEmzOtwzyjfMkuh7JmqFh+jzQ@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 790 bytes --]
On Tue, 4 Jun 2019, Linus Torvalds wrote:
> So I don't technically disagree with anything you say,
That's good to know!
> I just wanted
> to point out that as far as the kernel is concerned, we do have higher
> quality expectations from the compiler than just "technically valid
> according to the C standard".
Which suggests asking whether these higher expectations should be
reflected in the Linux Kernel Memory Model. So far we have largely
avoided doing that sort of thing, although there are a few exceptions.
(For example, we assume the compiler does not destroy address
dependencies from volatile reads -- but we also warn that this
assumption may fail if the programmer does not follow some rules
described in one of Paul's documentation files.)
Alan
next prev parent reply other threads:[~2019-06-04 17:00 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-10 0:57 [rcu] kernel BUG at include/linux/pagemap.h:149! Fengguang Wu
2015-09-10 0:57 ` Fengguang Wu
2015-09-10 10:25 ` Boqun Feng
2015-09-10 17:16 ` Paul E. McKenney
2015-09-10 17:16 ` Paul E. McKenney
2015-09-11 2:19 ` Boqun Feng
[not found] ` <CAJzB8QG=1iZW3dQEie6ZSTLv8GZ3YSut0aL1VU7LLmiHQ1B1DQ@mail.gmail.com>
2015-09-11 21:59 ` Paul E. McKenney
2015-09-11 21:59 ` Paul E. McKenney
2015-09-12 5:46 ` Boqun Feng
2015-09-21 19:30 ` Frederic Weisbecker
2015-09-21 19:30 ` Frederic Weisbecker
2015-09-21 20:43 ` Paul E. McKenney
2015-09-21 20:43 ` Paul E. McKenney
2019-06-02 5:56 ` rcu_read_lock lost its compiler barrier Herbert Xu
2019-06-02 5:56 ` Herbert Xu
2019-06-02 20:54 ` Linus Torvalds
2019-06-02 20:54 ` Linus Torvalds
2019-06-03 2:46 ` Herbert Xu
2019-06-03 2:46 ` Herbert Xu
2019-06-03 3:47 ` Paul E. McKenney
2019-06-03 4:01 ` Herbert Xu
2019-06-03 4:01 ` Herbert Xu
2019-06-03 4:17 ` Herbert Xu
2019-06-03 4:17 ` Herbert Xu
2019-06-03 7:23 ` Paul E. McKenney
2019-06-03 8:42 ` Paul E. McKenney
2019-06-03 15:26 ` David Laight
2019-06-03 15:40 ` Linus Torvalds
2019-06-03 15:40 ` Linus Torvalds
2019-06-03 5:26 ` Herbert Xu
2019-06-03 5:26 ` Herbert Xu
2019-06-03 6:42 ` Boqun Feng
2019-06-03 6:42 ` Boqun Feng
2019-06-03 20:03 ` Paul E. McKenney
2019-06-04 14:44 ` Alan Stern
2019-06-04 14:44 ` Alan Stern
2019-06-04 16:04 ` Linus Torvalds
2019-06-04 16:04 ` Linus Torvalds
2019-06-04 17:00 ` Alan Stern [this message]
2019-06-04 17:00 ` Alan Stern
2019-06-04 17:29 ` Linus Torvalds
2019-06-04 17:29 ` Linus Torvalds
2019-06-07 14:09 ` inet: frags: Turn fqdir->dead into an int for old Alphas Herbert Xu
2019-06-07 14:09 ` Herbert Xu
2019-06-07 15:26 ` Eric Dumazet
2019-06-07 15:26 ` Eric Dumazet
2019-06-07 15:32 ` Herbert Xu
2019-06-07 15:32 ` Herbert Xu
2019-06-07 16:13 ` Eric Dumazet
2019-06-07 16:13 ` Eric Dumazet
2019-06-07 16:19 ` Linus Torvalds
2019-06-07 16:19 ` Linus Torvalds
2019-06-08 15:27 ` Paul E. McKenney
2019-06-08 17:42 ` Linus Torvalds
2019-06-08 17:42 ` Linus Torvalds
2019-06-08 17:50 ` Linus Torvalds
2019-06-08 17:50 ` Linus Torvalds
2019-06-08 18:50 ` Paul E. McKenney
2019-06-08 18:14 ` Paul E. McKenney
2019-06-06 4:51 ` rcu_read_lock lost its compiler barrier Herbert Xu
2019-06-06 4:51 ` Herbert Xu
2019-06-06 6:05 ` Paul E. McKenney
2019-06-06 6:14 ` Herbert Xu
2019-06-06 6:14 ` Herbert Xu
2019-06-06 9:06 ` Paul E. McKenney
2019-06-06 9:28 ` Herbert Xu
2019-06-06 9:28 ` Herbert Xu
2019-06-06 10:58 ` Paul E. McKenney
2019-06-06 13:38 ` Herbert Xu
2019-06-06 13:38 ` Herbert Xu
2019-06-06 13:48 ` Paul E. McKenney
2019-06-06 8:16 ` Andrea Parri
2019-06-06 14:19 ` Alan Stern
2019-06-06 14:19 ` Alan Stern
2019-06-08 15:19 ` Paul E. McKenney
2019-06-08 15:56 ` Alan Stern
2019-06-08 15:56 ` Alan Stern
2019-06-08 16:31 ` Paul E. McKenney
2019-06-03 9:35 ` Paul E. McKenney
2019-06-06 8:38 ` Andrea Parri
2019-06-06 9:32 ` Herbert Xu
2019-06-06 9:32 ` Herbert Xu
2019-06-03 0:06 ` Paul E. McKenney
2019-06-03 3:03 ` Herbert Xu
2019-06-03 3:03 ` Herbert Xu
2019-06-03 9:27 ` Paul E. McKenney
2019-06-03 15:55 ` Linus Torvalds
2019-06-03 15:55 ` Linus Torvalds
2019-06-03 16:07 ` Linus Torvalds
2019-06-03 16:07 ` Linus Torvalds
2019-06-03 19:53 ` Paul E. McKenney
2019-06-03 20:24 ` Linus Torvalds
2019-06-03 20:24 ` Linus Torvalds
2019-06-04 21:14 ` Paul E. McKenney
2019-06-05 2:21 ` Herbert Xu
2019-06-05 2:21 ` Herbert Xu
2019-06-05 3:30 ` Paul E. McKenney
2019-06-06 4:37 ` Herbert Xu
2019-06-06 4:37 ` Herbert Xu
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=Pine.LNX.4.44L0.1906041251210.1731-100000@iolanthe.rowland.org \
--to=stern@rowland.harvard.edu \
--cc=andrea.parri@amarulasolutions.com \
--cc=boqun.feng@gmail.com \
--cc=davem@davemloft.net \
--cc=fengguang.wu@intel.com \
--cc=fweisbec@gmail.com \
--cc=herbert@gondor.apana.org.au \
--cc=j.alglave@ucl.ac.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@01.org \
--cc=luc.maranget@inria.fr \
--cc=netdev@vger.kernel.org \
--cc=paulmck@linux.ibm.com \
--cc=torvalds@linux-foundation.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.