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SubjectRe: [PATCH 1/3] Revert "cpu/hotplug: Ignore pm_wakeup_pending() for disable_nonboot_cpus()"
Date
On Thursday, April 9, 2020 1:27:40 PM CEST Qais Yousef wrote:
> This issue was fixed already by:
>
> commit d66b16f5df4b ("arm64: Don't use disable_nonboot_cpus()")
> commit dddf3578e0d4 ("ARM: Don't use disable_nonboot_cpus()")
>
> The only caller of disable_nonboot_cpus() is x86, which is in a proper
> suspend/resume path and due to the reverted patch lost its ability to
> early abort due to a pending wakeup.
>
> The fix that is being reverted is arguably a better one to backport to
> stable trees. But it highlights the confusion about using
> disable_nonboot_cpus() API.
>
> This is a preparation to remove disable_nonboot_cpus() in favor of
> freeze_secondary_cpus().
>
> This reverts commit e98eac6ff1b45e4e73f2e6031b37c256ccb5d36b.
>
> Signed-off-by: Qais Yousef <qais.yousef@arm.com>
> CC: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> CC: Len Brown <len.brown@intel.com>
> CC: Pavel Machek <pavel@ucw.cz>
> CC: Ingo Molnar <mingo@redhat.com>
> CC: Borislav Petkov <bp@alien8.de>
> CC: "H. Peter Anvin" <hpa@zytor.com>
> CC: x86@kernel.org
> CC: Todd E Brandt <todd.e.brandt@linux.intel.com>
> CC: linux-pm@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> ---
> include/linux/cpu.h | 12 +++---------
> kernel/cpu.c | 4 ++--
> 2 files changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/cpu.h b/include/linux/cpu.h
> index beaed2dc269e..9ead281157d3 100644
> --- a/include/linux/cpu.h
> +++ b/include/linux/cpu.h
> @@ -144,18 +144,12 @@ static inline void get_online_cpus(void) { cpus_read_lock(); }
> static inline void put_online_cpus(void) { cpus_read_unlock(); }
>
> #ifdef CONFIG_PM_SLEEP_SMP
> -int __freeze_secondary_cpus(int primary, bool suspend);
> -static inline int freeze_secondary_cpus(int primary)
> -{
> - return __freeze_secondary_cpus(primary, true);
> -}
> -
> +extern int freeze_secondary_cpus(int primary);
> static inline int disable_nonboot_cpus(void)
> {
> - return __freeze_secondary_cpus(0, false);
> + return freeze_secondary_cpus(0);
> }
> -
> -void enable_nonboot_cpus(void);
> +extern void enable_nonboot_cpus(void);
>
> static inline int suspend_disable_secondary_cpus(void)
> {
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index 12ae636e9cb6..30848496cbc7 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -1327,7 +1327,7 @@ void bringup_nonboot_cpus(unsigned int setup_max_cpus)
> #ifdef CONFIG_PM_SLEEP_SMP
> static cpumask_var_t frozen_cpus;
>
> -int __freeze_secondary_cpus(int primary, bool suspend)
> +int freeze_secondary_cpus(int primary)
> {
> int cpu, error = 0;
>
> @@ -1352,7 +1352,7 @@ int __freeze_secondary_cpus(int primary, bool suspend)
> if (cpu == primary)
> continue;
>
> - if (suspend && pm_wakeup_pending()) {
> + if (pm_wakeup_pending()) {
> pr_info("Wakeup pending. Abort CPU freeze\n");
> error = -EBUSY;
> break;
>

I would do this the other way around:

1. Make x86 call freeze_secondary_cpus() directly, rename
enable_nonboot_cpus() and drop disable_nonboot_cpus().
2. Get rid of __freeze_secondary_cpus().



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