From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-kernel@vger.kernel.org, jgross@suse.com,
richard.henderson@linaro.org, ink@jurassic.park.msu.ru,
mattst88@gmail.com, linux-alpha@vger.kernel.org,
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christophe.leroy@csgroup.eu, linuxppc-dev@lists.ozlabs.org,
ysato@users.sourceforge.jp, dalias@libc.org,
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hpa@zytor.com, chris@zankel.net, jcmvbkbc@gmail.com,
linux-xtensa@linux-xtensa.org, peterz@infradead.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
vschneid@redhat.com, paulmck@kernel.org
Subject: Re: [PATCH v2 03/24] arm/cpu: Make sure arch_cpu_idle_dead() doesn't return
Date: Tue, 14 Feb 2023 11:15:23 +0000 [thread overview]
Message-ID: <Y+ttS0japRCzHoFM@shell.armlinux.org.uk> (raw)
In-Reply-To: <ed361403b8ee965f758fe491c47336dddcfb8fd5.1676358308.git.jpoimboe@kernel.org>
On Mon, Feb 13, 2023 at 11:05:37PM -0800, Josh Poimboeuf wrote:
> arch_cpu_idle_dead() doesn't return. Make that more explicit with a
> BUG().
>
> BUG() is preferable to unreachable() because BUG() is a more explicit
> failure mode and avoids undefined behavior like falling off the edge of
> the function into whatever code happens to be next.
This is silly. Just mark the function __noreturn and be done with it.
If the CPU ever executes code past the "b" instruction, it's already
really broken that the extra instructions that BUG() gives will be
meaningless.
This patch does nothing except add yet more bloat the kernel.
Sorry, but NAK.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2023-02-14 11:16 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-14 7:05 [PATCH v2 00/24] cpu,sched: Mark arch_cpu_idle_dead() __noreturn Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 01/24] alpha/cpu: Expose arch_cpu_idle_dead()'s prototype declaration Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 02/24] alpha/cpu: Make sure arch_cpu_idle_dead() doesn't return Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 03/24] arm/cpu: " Josh Poimboeuf
2023-02-14 11:15 ` Russell King (Oracle) [this message]
2023-02-14 18:39 ` Josh Poimboeuf
2023-02-14 22:01 ` Russell King (Oracle)
2023-02-16 18:38 ` [PATCH v2.1 03/24] arm/cpu: Add unreachable() to arch_cpu_idle_dead() Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 04/24] arm64/cpu: Mark cpu_die() __noreturn Josh Poimboeuf
2023-02-14 8:13 ` Philippe Mathieu-Daudé
2023-02-15 13:09 ` Mark Rutland
2023-02-15 19:45 ` Josh Poimboeuf
2023-02-16 18:41 ` [PATCH v2.1 " Josh Poimboeuf
2023-03-02 10:55 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 05/24] csky/cpu: Make sure arch_cpu_idle_dead() doesn't return Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 06/24] ia64/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-02-14 8:07 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 07/24] loongarch/cpu: Make sure play_dead() doesn't return Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 08/24] loongarch/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-02-14 8:06 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 09/24] mips/cpu: Expose play_dead()'s prototype definition Josh Poimboeuf
2023-02-14 7:46 ` Philippe Mathieu-Daudé
2023-02-14 18:11 ` Josh Poimboeuf
2023-02-15 8:29 ` Philippe Mathieu-Daudé
2023-02-16 18:42 ` [PATCH v2.1 " Josh Poimboeuf
2023-03-01 18:16 ` Josh Poimboeuf
2023-03-02 10:54 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 10/24] mips/cpu: Make sure play_dead() doesn't return Josh Poimboeuf
2023-02-14 7:50 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 11/24] mips/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-02-14 7:50 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 12/24] powerpc/cpu: Mark start_secondary_resume() __noreturn Josh Poimboeuf
2023-02-14 7:19 ` Christophe Leroy
2023-02-14 7:05 ` [PATCH v2 13/24] sh/cpu: Make sure play_dead() doesn't return Josh Poimboeuf
2023-02-14 7:57 ` Philippe Mathieu-Daudé
2023-02-14 18:28 ` Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 14/24] sh/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 15/24] sh/cpu: Expose arch_cpu_idle_dead()'s prototype definition Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 16/24] sparc/cpu: Mark cpu_play_dead() __noreturn Josh Poimboeuf
2023-02-14 7:52 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 17/24] x86/cpu: Make sure play_dead() doesn't return Josh Poimboeuf
2023-02-14 8:05 ` Philippe Mathieu-Daudé
2023-02-14 7:05 ` [PATCH v2 18/24] x86/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return Josh Poimboeuf
2023-02-14 7:55 ` Philippe Mathieu-Daudé
2023-02-14 18:23 ` Josh Poimboeuf
2023-02-14 19:29 ` Steven Rostedt
2023-02-14 19:48 ` Max Filippov
2023-02-14 20:19 ` Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 20/24] xtensa/cpu: Mark cpu_die() __noreturn Josh Poimboeuf
2023-02-14 12:47 ` Max Filippov
2023-02-14 7:05 ` [PATCH v2 21/24] sched/idle: Make sure weak version of arch_cpu_idle_dead() doesn't return Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 22/24] objtool: Include weak functions in 'global_noreturns' check Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 23/24] init: Make arch_call_rest_init() and rest_init() __noreturn Josh Poimboeuf
2023-02-14 7:05 ` [PATCH v2 24/24] sched/idle: Mark arch_cpu_idle_dead() __noreturn Josh Poimboeuf
2023-02-14 9:25 ` [PATCH v2 00/24] cpu,sched: " Philippe Mathieu-Daudé
2023-02-14 18:29 ` Josh Poimboeuf
2023-02-15 22:22 ` Paul E. McKenney
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