Re: linux/bitops.h

From	John Denker <jsd@av8n.com>
Newsgroups	linux.kernel
Subject	Re: linux/bitops.h
Date	2016-05-05 00:10 +0200
Message-ID	<rvd9v-3OM-13@gated-at.bofh.it> (permalink)
References	(4 earlier) <rv9IB-Ky-1@gated-at.bofh.it> <rv9Sj-Pg-59@gated-at.bofh.it> <rvalk-1lA-11@gated-at.bofh.it> <rvcQ9-3lE-3@gated-at.bofh.it> <rvcZQ-3pD-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 05/04/2016 02:56 PM, H. Peter Anvin wrote:
>> Beware that shifting by an amount >= the number of bits in the
>> word remains Undefined Behavior.

> This construct has been supported as a rotate since at least gcc2.

How then should we understand the story told in commit d7e35dfa?
Is the story wrong?

At the very least, something inconsistent is going on.  There
are 8 functions.  Why did d7e35dfa change one of them but
not the other 7?

Thread

[RFC PATCH 0/3] random: replace urandom pool with a CRNG Theodore Ts'o <tytso@mit.edu> - 2016-05-02 08:30 +0200
  [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG Theodore Ts'o <tytso@mit.edu> - 2016-05-02 08:30 +0200
    Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG Stephan Mueller <smueller@chronox.de> - 2016-05-03 11:00 +0200
      Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG Jeffrey Walton <noloader@gmail.com> - 2016-05-04 19:00 +0200
      Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG tytso@mit.edu - 2016-05-04 19:40 +0200
        Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 20:00 +0200
    Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG Stephan Mueller <smueller@chronox.de> - 2016-05-03 11:40 +0200
      Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG Stephan Mueller <smueller@chronox.de> - 2016-05-04 08:30 +0200
    Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG Jeffrey Walton <noloader@gmail.com> - 2016-05-04 16:50 +0200
      Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG tytso@mit.edu - 2016-05-04 19:50 +0200
        Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG Jeffrey Walton <noloader@gmail.com> - 2016-05-04 20:30 +0200
          Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 20:40 +0200
            Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG tytso@thunk.org - 2016-05-04 21:10 +0200
              Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG "H. Peter Anvin" <hpa@zytor.com> - 2016-05-04 23:00 +0200
              Re: [PATCH 1/3] random: replace non-blocking pool with a  Chacha20-based CRNG John Denker <jsd@av8n.com> - 2016-05-04 23:50 +0200
                Re: better patch for linux/bitops.h John Denker <jsd@av8n.com> - 2016-05-05 00:00 +0200
                Re: better patch for linux/bitops.h Jeffrey Walton <noloader@gmail.com> - 2016-05-05 03:40 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 04:50 +0200
                Re: better patch for linux/bitops.h Jeffrey Walton <noloader@gmail.com> - 2016-05-05 05:00 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 05:10 +0200
                Re: better patch for linux/bitops.h Jeffrey Walton <noloader@gmail.com> - 2016-05-05 05:40 +0200
                Re: better patch for linux/bitops.h Theodore Ts'o <tytso@mit.edu> - 2016-05-05 06:00 +0200
                Re: better patch for linux/bitops.h Jeffrey Walton <noloader@gmail.com> - 2016-05-05 06:10 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 08:40 +0200
                Re: UB in general ... and linux/bitops.h in particular John Denker <jsd@av8n.com> - 2016-05-05 18:20 +0200
                Re: UB in general ... and linux/bitops.h in particular Andi Kleen <andi@firstfloor.org> - 2016-05-05 19:40 +0200
                Re: UB in general ... and linux/bitops.h in particular Jeffrey Walton <noloader@gmail.com> - 2016-05-06 04:30 +0200
                Re: better patch for linux/bitops.h Sandy Harris <sandyinchina@gmail.com> - 2016-05-05 23:40 +0200
                Re: better patch for linux/bitops.h tytso@mit.edu - 2016-05-06 00:20 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-06 00:30 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-06 00:40 +0200
                Re: better patch for linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-06 02:20 +0200
                Re: [PATCH 1/3] random: replace non-blocking pool with a Chacha20-based CRNG "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 00:00 +0200
                Re: linux/bitops.h John Denker <jsd@av8n.com> - 2016-05-05 00:10 +0200
                Re: linux/bitops.h Andi Kleen <andi@firstfloor.org> - 2016-05-05 01:10 +0200
                Re: linux/bitops.h John Denker <jsd@av8n.com> - 2016-05-05 02:20 +0200
                Re: linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 03:30 +0200
                Re: linux/bitops.h Jeffrey Walton <noloader@gmail.com> - 2016-05-05 03:30 +0200
                Re: linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-05 02:40 +0200
                Re: linux/bitops.h Linus Torvalds <torvalds@linux-foundation.org> - 2016-05-05 02:50 +0200
                Re: linux/bitops.h Sasha Levin <sasha.levin@oracle.com> - 2016-05-06 22:10 +0200
                Re: linux/bitops.h Sasha Levin <sasha.levin@oracle.com> - 2016-05-06 22:10 +0200
                Re: linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-06 22:30 +0200
                Re: linux/bitops.h "H. Peter Anvin" <hpa@zytor.com> - 2016-05-06 22:40 +0200
  [PATCH 2/3] random: make /dev/urandom scalable for silly userspace programs Theodore Ts'o <tytso@mit.edu> - 2016-05-02 08:30 +0200
    Re: [PATCH 2/3] random: make /dev/urandom scalable for silly userspace programs Stephan Mueller <smueller@chronox.de> - 2016-05-02 09:10 +0200
      Re: [PATCH 2/3] random: make /dev/urandom scalable for silly  userspace programs Theodore Ts'o <tytso@mit.edu> - 2016-05-02 15:00 +0200
        Re: [PATCH 2/3] random: make /dev/urandom scalable for silly  userspace programs Theodore Ts'o <tytso@mit.edu> - 2016-05-02 15:50 +0200
          Re: [PATCH 2/3] random: make /dev/urandom scalable for silly userspace programs Stephan Mueller <smueller@chronox.de> - 2016-05-02 16:00 +0200
  [PATCH 3/3] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o <tytso@mit.edu> - 2016-05-02 08:30 +0200
    Re: [PATCH 3/3] random: add interrupt callback to VMBus IRQ handler Jeffrey Walton <noloader@gmail.com> - 2016-05-02 11:10 +0200
      Re: [PATCH 3/3] random: add interrupt callback to VMBus IRQ handler Stephan Mueller <smueller@chronox.de> - 2016-05-02 11:20 +0200
        Re: [PATCH 3/3] random: add interrupt callback to VMBus IRQ handler Theodore Ts'o <tytso@mit.edu> - 2016-05-02 15:00 +0200

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