From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
"the arch/x86 maintainers" <x86@kernel.org>,
Len Brown <lenb@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, Stable <stable@vger.kernel.org>,
kernel test robot <lkp@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ACPI: processor: Fix build when CONFIG_ACPI_PROCESSOR=m
Date: Tue, 6 Apr 2021 15:22:00 +0200 [thread overview]
Message-ID: <CAJZ5v0hpkF-acQAomZZKN=r00gNy831R7J-ZWZgWnoCJe5xSkg@mail.gmail.com> (raw)
In-Reply-To: <20210406125047.547501-1-vkuznets@redhat.com>
On Tue, Apr 6, 2021 at 2:50 PM Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>
> Commit 8cdddd182bd7 ("ACPI: processor: Fix CPU0 wakeup in
> acpi_idle_play_dead()") tried to fix CPU0 hotplug breakage by copying
> wakeup_cpu0() + start_cpu0() logic from hlt_play_dead()//mwait_play_dead()
> into acpi_idle_play_dead(). The problem is that these functions are not
> exported to modules so when CONFIG_ACPI_PROCESSOR=m build fails.
>
> The issue could've been fixed by exporting both wakeup_cpu0()/start_cpu0()
> (the later from assembly) but it seems putting the whole pattern into a
> new function and exporting it instead is better.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: 8cdddd182bd7 ("CPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead()")
> Cc: <stable@vger.kernel.org> # 5.10+
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> arch/x86/include/asm/smp.h | 2 +-
> arch/x86/kernel/smpboot.c | 15 ++++++++++-----
> drivers/acpi/processor_idle.c | 3 +--
> 3 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
> index 57ef2094af93..6f79deb1f970 100644
> --- a/arch/x86/include/asm/smp.h
> +++ b/arch/x86/include/asm/smp.h
> @@ -132,7 +132,7 @@ void native_play_dead(void);
> void play_dead_common(void);
> void wbinvd_on_cpu(int cpu);
> int wbinvd_on_all_cpus(void);
> -bool wakeup_cpu0(void);
> +void wakeup_cpu0_if_needed(void);
>
> void native_smp_send_reschedule(int cpu);
> void native_send_call_func_ipi(const struct cpumask *mask);
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index f877150a91da..9547d870ee27 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1659,7 +1659,7 @@ void play_dead_common(void)
> local_irq_disable();
> }
>
> -bool wakeup_cpu0(void)
> +static bool wakeup_cpu0(void)
> {
> if (smp_processor_id() == 0 && enable_start_cpu0)
> return true;
> @@ -1667,6 +1667,13 @@ bool wakeup_cpu0(void)
> return false;
> }
>
> +void wakeup_cpu0_if_needed(void)
> +{
> + if (wakeup_cpu0())
> + start_cpu0();
Note that all of the callers of wakeup_cpu0 do the above, so maybe
make them all use the new function?
In which case it can be rewritten in the following way
void cond_wakeup_cpu0(void)
{
if (smp_processor_id() == 0 && enable_start_cpu0)
start_cpu0();
}
EXPORT_SYMBOL_GPL(cond_wakeup_cpu0);
Also please add a proper kerneldoc comment to it and maybe drop the
comments at the call sites?
> +}
> +EXPORT_SYMBOL_GPL(wakeup_cpu0_if_needed);
> +
> /*
> * We need to flush the caches before going to sleep, lest we have
> * dirty data in our caches when we come back up.
> @@ -1737,8 +1744,7 @@ static inline void mwait_play_dead(void)
> /*
> * If NMI wants to wake up CPU0, start CPU0.
> */
> - if (wakeup_cpu0())
> - start_cpu0();
> + wakeup_cpu0_if_needed();
> }
> }
>
> @@ -1752,8 +1758,7 @@ void hlt_play_dead(void)
> /*
> * If NMI wants to wake up CPU0, start CPU0.
> */
> - if (wakeup_cpu0())
> - start_cpu0();
> + wakeup_cpu0_if_needed();
> }
> }
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index 768a6b4d2368..de15116b754a 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -545,8 +545,7 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
>
> #if defined(CONFIG_X86) && defined(CONFIG_HOTPLUG_CPU)
> /* If NMI wants to wake up CPU0, start CPU0. */
> - if (wakeup_cpu0())
> - start_cpu0();
> + wakeup_cpu0_if_needed();
> #endif
> }
>
> --
> 2.30.2
>
next prev parent reply other threads:[~2021-04-06 13:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 12:50 [PATCH] ACPI: processor: Fix build when CONFIG_ACPI_PROCESSOR=m Vitaly Kuznetsov
2021-04-06 13:22 ` Rafael J. Wysocki [this message]
2021-04-06 13:37 ` Vitaly Kuznetsov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAJZ5v0hpkF-acQAomZZKN=r00gNy831R7J-ZWZgWnoCJe5xSkg@mail.gmail.com' \
--to=rafael@kernel.org \
--cc=bp@alien8.de \
--cc=hpa@zytor.com \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkp@intel.com \
--cc=mingo@redhat.com \
--cc=rjw@rjwysocki.net \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).