From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: arm64: Fix machine_shutdown() definition
Date: Tue, 06 May 2014 10:35:33 -0600 [thread overview]
Message-ID: <53690F55.6030504@wwwdotorg.org> (raw)
In-Reply-To: <1399391708-13442-1-git-send-email-arunks.linux@gmail.com>
On 05/06/2014 09:55 AM, arunks.linux at gmail.com wrote:
> From: Arun KS <arun.linux@gmail•com>
>
> machine_shutdown() is a hook for kexec. Add a comment saying so, since
> it isn't obvious from the function name.
>
> Halt, power-off, and restart have different requirements re: stopping
> secondary CPUs than kexec has. The former simply require the secondary
> CPUs to be quiesced somehow, whereas kexec requires them to be
> completely non-operational, so that no matter where the kexec target
> images are written in RAM, they won't influence operation of the
> secondary CPUS,which could happen if the CPUs were still executing some
> kind of pin loop. To this end, modify machine_halt, power_off, and
> restart to call smp_send_stop() directly, rather than calling
> machine_shutdown().
>
> In machine_shutdown(), replace the call to smp_send_stop() with a call
> to disable_nonboot_cpus(). This completely disables all but one CPU,
> thus satisfying the kexec requirements a couple paragraphs above.
>
> Signed-off-by: Stephen Warren <swarren@nvidia•com>
> Signed-off-by: Arun KS <getarunks@gmail•com>
> Signed-off-by: Arun KS <arunks.linux@gmail•com>
It's a bit odd to include my s-o-b here when I didn't actually write
this particular patch. No doubt it's included because I wrote an
identical patch for arch/arm/.
Rather than including my s-o-b here, perhaps simply including the
following paragraph in the commit decription would be better:
This patch ports most of commit 19ab428f4b79 "ARM: 7759/1: decouple CPU
offlining from reboot/shutdown" by Stephen Warren from arch/arm to
arch/arm64.
Or, I sometimes use the following tag instead of s-o-b:
Based-on-work-by: Stephen Warren <swarren@nvidia•com>
Including two s-o-b for yourself probably isn't necesary.
Do you need to include an equivalent of the following from my original
patch to arch/arm/?
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 239fa96c12bb..2651b1da1c56 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -2016,7 +2016,7 @@ config XIP_PHYS_ADDR
>
> config KEXEC
> bool "Kexec system call (EXPERIMENTAL)"
> - depends on (!SMP || HOTPLUG_CPU)
> + depends on (!SMP || PM_SLEEP_SMP)
> help
> kexec is a system call that implements the ability to shutdown your
> current kernel, and to start another kernel. It is like a reboot
> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
> index 8ef8c9337809..4fb074c446bf 100644
> --- a/arch/arm/kernel/machine_kexec.c
> +++ b/arch/arm/kernel/machine_kexec.c
> @@ -134,6 +134,10 @@ void machine_kexec(struct kimage *image)
> unsigned long reboot_code_buffer_phys;
> void *reboot_code_buffer;
>
> + if (num_online_cpus() > 1) {
> + pr_err("kexec: error: multiple CPUs still online\n");
> + return;
> + }
>
> page_list = image->head & PAGE_MASK;
>
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 550d63cef68e..5919eb451bb9 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -651,17 +651,6 @@ void smp_send_reschedule(int cpu)
> smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
> }
>
> -#ifdef CONFIG_HOTPLUG_CPU
> -static void smp_kill_cpus(cpumask_t *mask)
> -{
> - unsigned int cpu;
> - for_each_cpu(cpu, mask)
> - platform_cpu_kill(cpu);
> -}
> -#else
> -static void smp_kill_cpus(cpumask_t *mask) { }
> -#endif
> -
> void smp_send_stop(void)
> {
> unsigned long timeout;
> @@ -679,8 +668,6 @@ void smp_send_stop(void)
>
> if (num_online_cpus() > 1)
> pr_warning("SMP: failed to stop secondary CPUs\n");
> -
> - smp_kill_cpus(&mask);
> }
>
> /*
next prev parent reply other threads:[~2014-05-06 16:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-06 15:55 arm64: Fix machine_shutdown() definition arunks.linux at gmail.com
2014-05-06 15:55 ` arm64: Fix deadlock scenario with smp_send_stop() arunks.linux at gmail.com
2014-05-06 16:35 ` Stephen Warren [this message]
2014-05-07 1:31 ` arm64: Fix machine_shutdown() definition Arun KS
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