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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jason Gunthorpe <jgg@ziepe.ca>, Jakob <jakobkoschel@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Arnd Bergman <arnd@arndb.de>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Mike Rapoport <rppt@kernel.org>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Brian Johannesmeyer <bjohannesmeyer@gmail.com>,
	Cristiano Giuffrida <c.giuffrida@vu.nl>,
	"Bos, H.J." <h.j.bos@vu.nl>
Subject: Re: [RFC PATCH 04/13] vfio/mdev: remove the usage of the list iterator after the loop
Date: Wed, 23 Feb 2022 12:34:18 -0800	[thread overview]
Message-ID: <CAHk-=whpK93+mF8CPJZo0KxDeHrV2GL05=HT7=y+GnhcNbNyUA@mail.gmail.com> (raw)
In-Reply-To: <5a476b24-0f34-91d4-84a4-699e8c374abe@rasmusvillemoes.dk>

On Wed, Feb 23, 2022 at 12:19 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> I have often wished that the iterator macros would consistently set the
> loop variable to NULL upon reaching the end.

I really think the rule should be that to a 99% approximation, we
should strive only ever use the iterated-upon value *inside* the loop.

No, that's now how we do it now. But I think the "break out and do the
work outside the loop" case is kind of broken anyway. It makes you
test the condition twice - and while a compiler might be smart enough
to optimize the second test away, it's still just plain ugly.

             Linus

  reply	other threads:[~2022-02-23 20:34 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-17 18:48 [RFC PATCH 00/13] Proposal for speculative safe list iterator Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 01/13] list: introduce speculative safe list_for_each_entry() Jakob Koschel
2022-02-17 19:29   ` Greg Kroah-Hartman
2022-02-18 16:29     ` Jann Horn
2022-02-18 16:29   ` Jann Horn
2022-02-23 14:32     ` Jakob
2022-02-19 19:44   ` Jann Horn
2022-02-17 18:48 ` [RFC PATCH 02/13] scripts: coccinelle: adapt to find list_for_each_entry nospec issues Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 03/13] usb: remove the usage of the list iterator after the loop Jakob Koschel
2022-02-17 19:28   ` Linus Torvalds
2022-02-23 14:13     ` Jakob
2022-02-23 14:16       ` Jakob
2022-02-24 10:33         ` Greg Kroah-Hartman
2022-02-24 17:56           ` Linus Torvalds
     [not found]         ` <6d191223d93249a98511177d4af08420@pexch012b.vu.local>
2022-02-24 10:46           ` Cristiano Giuffrida
2022-02-24 11:26             ` Greg Kroah-Hartman
2022-02-23 18:47       ` Linus Torvalds
2022-02-23 19:23         ` Linus Torvalds
2022-02-23 19:43           ` Linus Torvalds
2022-02-23 20:24           ` Arnd Bergmann
2022-02-23 20:43             ` Linus Torvalds
2022-02-23 20:48               ` Arnd Bergmann
2022-02-23 21:53                 ` Linus Torvalds
2022-02-24 16:04                   ` Nathan Chancellor
2022-02-23 20:54               ` Linus Torvalds
2022-02-23 22:21                 ` David Laight
2022-02-25 21:36                 ` Uecker, Martin
2022-02-25 22:02                   ` Linus Torvalds
2022-02-26  1:21                     ` Martin Uecker
2022-02-27 18:12                       ` Miguel Ojeda
2022-02-28  7:08                         ` Martin Uecker
2022-02-28 13:49                           ` Miguel Ojeda
2022-03-01 20:26                             ` Linus Torvalds
2022-03-02  7:27                               ` Martin Uecker
2022-02-26 12:42           ` Segher Boessenkool
2022-02-26 22:14             ` Arnd Bergmann
2022-02-26 23:03               ` Linus Torvalds
2022-02-27  1:19                 ` Segher Boessenkool
2022-02-27  1:09               ` Segher Boessenkool
2022-02-27  7:10                 ` David Laight
2022-02-27 11:32                   ` Segher Boessenkool
2022-02-27 18:09                     ` Miguel Ojeda
2022-02-27 20:17                       ` Segher Boessenkool
2022-02-27 21:04                         ` Linus Torvalds
2022-02-28  6:15                           ` David Laight
2022-02-27 22:43                         ` Miguel Ojeda
2022-02-27 21:28                 ` Arnd Bergmann
2022-02-27 22:43                   ` Segher Boessenkool
2022-02-17 18:48 ` [RFC PATCH 04/13] vfio/mdev: " Jakob Koschel
2022-02-18 15:12   ` Jason Gunthorpe
2022-02-23 14:18     ` Jakob
2022-02-23 19:06       ` Linus Torvalds
2022-02-23 19:12         ` Jason Gunthorpe
2022-02-23 19:31           ` Linus Torvalds
2022-02-23 20:15             ` Jakob
2022-02-23 20:22               ` Linus Torvalds
2022-02-23 22:08                 ` Jakob
2022-02-23 20:19             ` Rasmus Villemoes
2022-02-23 20:34               ` Linus Torvalds [this message]
2022-02-17 18:48 ` [RFC PATCH 05/13] drivers/perf: " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 06/13] ARM: mmp: " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 07/13] udp_tunnel: " Jakob Koschel
2022-02-23 20:00   ` Christophe JAILLET
2022-02-24  6:20     ` Dan Carpenter
2022-02-17 18:48 ` [RFC PATCH 08/13] net: dsa: future proof usage of " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 09/13] drbd: " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 10/13] powerpc/spufs: " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 11/13] ath6kl: remove use " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 12/13] staging: greybus: audio: Remove usage " Jakob Koschel
2022-02-17 18:48 ` [RFC PATCH 13/13] scsi: mpt3sas: comment about invalid usage of the list iterator Jakob Koschel

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