On Tue, Apr 6, 2021 at 5:56 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
Applied as 5.12-rc material, thanks!
Changes since v2:
- Use proper kerneldoc format [Rafael J. Wysocki]
arch/x86/include/asm/smp.h | 2 +- arch/x86/kernel/smpboot.c | 26 ++++++++++++-------------- drivers/acpi/processor_idle.c | 4 +--- 3 files changed, 14 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h index 57ef2094af93..630ff08532be 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 cond_wakeup_cpu0(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..16703c35a944 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1659,13 +1659,17 @@ void play_dead_common(void) local_irq_disable(); }
-bool wakeup_cpu0(void) +/**
- cond_wakeup_cpu0 - Wake up CPU0 if needed.
- If NMI wants to wake up CPU0, start CPU0.
- */
+void cond_wakeup_cpu0(void) { if (smp_processor_id() == 0 && enable_start_cpu0)
return true;return false;
start_cpu0();} +EXPORT_SYMBOL_GPL(cond_wakeup_cpu0);
/*
- We need to flush the caches before going to sleep, lest we have
@@ -1734,11 +1738,8 @@ static inline void mwait_play_dead(void) __monitor(mwait_ptr, 0, 0); mb(); __mwait(eax, 0);
/** If NMI wants to wake up CPU0, start CPU0.*/if (wakeup_cpu0())start_cpu0();
cond_wakeup_cpu0(); }}
@@ -1749,11 +1750,8 @@ void hlt_play_dead(void)
while (1) { native_halt();
/** If NMI wants to wake up CPU0, start CPU0.*/if (wakeup_cpu0())start_cpu0();
cond_wakeup_cpu0(); }}
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 768a6b4d2368..4e2d76b8b697 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -544,9 +544,7 @@ static int acpi_idle_play_dead(struct cpuidle_device *dev, int index) return -ENODEV;
#if defined(CONFIG_X86) && defined(CONFIG_HOTPLUG_CPU)
/* If NMI wants to wake up CPU0, start CPU0. */if (wakeup_cpu0())start_cpu0();
cond_wakeup_cpu0();#endif }
-- 2.30.2