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From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Max Filippov <jcmvbkbc@gmail.com>
Cc: juri.lelli@redhat.com, dalias@libc.org,
	linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
	peterz@infradead.org, catalin.marinas@arm.com,
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	"Philippe Mathieu-Daudé" <philmd@linaro.org>,
	bristot@redhat.com, linux-kernel@vger.kernel.org,
	linux-alpha@vger.kernel.org, bp@alien8.de,
	linuxppc-dev@lists.ozlabs.org, davem@davemloft.net
Subject: Re: [PATCH v2 19/24] xtensa/cpu: Make sure cpu_die() doesn't return
Date: Tue, 14 Feb 2023 12:19:09 -0800	[thread overview]
Message-ID: <20230214201909.flqc3g3njnbl5hun@treble> (raw)
In-Reply-To: <CAMo8BfLzV0Oe_i-QrMzE-BE028s6GNvOd827N5+tteELidjpvA@mail.gmail.com>

On Tue, Feb 14, 2023 at 11:48:41AM -0800, Max Filippov wrote:
> On Tue, Feb 14, 2023 at 10:23 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
> > On Tue, Feb 14, 2023 at 08:55:32AM +0100, Philippe Mathieu-Daudé wrote:
> > > Can you update the documentation along? Currently we have:
> > >
> > >   /*
> > >    * Called from the idle thread for the CPU which has been shutdown.
> > >    *
> > >    * Note that we disable IRQs here, but do not re-enable them
> > >    * before returning to the caller. This is also the behaviour
> > >    * of the other hotplug-cpu capable cores, so presumably coming
> > >    * out of idle fixes this.
> > >    */
> >
> > void __ref cpu_die(void)
> > {
> >         idle_task_exit();
> >         local_irq_disable();
> >         __asm__ __volatile__(
> >                         "       movi    a2, cpu_restart\n"
> >                         "       jx      a2\n");
> >
> >         BUG();
> > }
> >
> > Hm, not only is the comment wrong, but it seems to be branching to
> > cpu_restart?  That doesn't seem right at all.
> 
> Perhaps the name is a bit misleading. The CPU that enters 'cpu_restart'
> loops there until a call to 'boot_secondary' releases it, after which it goes
> to '_startup'. So it is a restart, but not immediate.

Ah, I see.  That sounds similar to what Xen does.

-- 
Josh

  reply	other threads:[~2023-02-14 20:19 UTC|newest]

Thread overview: 82+ 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 02/24] alpha/cpu: Make sure arch_cpu_idle_dead() doesn't return Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 03/24] arm/cpu: " Josh Poimboeuf
2023-02-14 11:15   ` Russell King (Oracle)
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
2023-03-10 20:54           ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54           ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 05/24] csky/cpu: Make sure arch_cpu_idle_dead() doesn't return Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 07/24] loongarch/cpu: Make sure play_dead() doesn't return Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54           ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 14/24] sh/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 15/24] sh/cpu: Expose arch_cpu_idle_dead()'s prototype definition Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  7:05 ` [PATCH v2 18/24] x86/cpu: Mark play_dead() __noreturn Josh Poimboeuf
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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 [this message]
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for 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
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Josh Poimboeuf
2023-02-14  8:38 ` [PATCH v2 25/24] x86/cpu: Expose arch_cpu_idle_dead()'s prototype definition Philippe Mathieu-Daudé
2023-03-10 20:54   ` [tip: objtool/core] " tip-bot2 for Philippe Mathieu-Daudé
2023-02-14  9:25 ` [PATCH v2 00/24] cpu,sched: Mark arch_cpu_idle_dead() __noreturn Philippe Mathieu-Daudé
2023-02-14 18:29   ` Josh Poimboeuf
2023-02-15 22:22 ` Paul E. McKenney

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