[PATCH] x86-64: Fix interrupt race in idle callback (3rd try)
Idle callbacks has some races when enter_idle() sets isidle and subsequent interrupts that can happen on that CPU, before CPU goes to idle. Due to this, an IDLE_END can get called before IDLE_START. To avoid these races, disable interrupts before enter_idle and make sure that all idle routines do not enable interrupts before entering idle. Note that poll_idle() still has a this race as it has to enable interrupts before going to idle. But, all other idle routines have the race fixed. Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Andi Kleen <ak@suse.de>
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@ -127,6 +127,7 @@ static void default_idle(void)
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*/
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static void poll_idle (void)
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{
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local_irq_enable();
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cpu_relax();
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}
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@ -208,6 +209,12 @@ void cpu_idle (void)
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idle = default_idle;
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if (cpu_is_offline(smp_processor_id()))
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play_dead();
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/*
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* Idle routines should keep interrupts disabled
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* from here on, until they go to idle.
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* Otherwise, idle callbacks can misfire.
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*/
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local_irq_disable();
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enter_idle();
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idle();
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/* In many cases the interrupt that ended idle
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@ -245,8 +252,16 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
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/* Default MONITOR/MWAIT with no hints, used for default C1 state */
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static void mwait_idle(void)
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{
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local_irq_enable();
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mwait_idle_with_hints(0,0);
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if (!need_resched()) {
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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smp_mb();
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if (!need_resched())
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__sti_mwait(0, 0);
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else
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local_irq_enable();
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} else {
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local_irq_enable();
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}
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}
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void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
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@ -475,6 +475,14 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
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: :"a" (eax), "c" (ecx));
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}
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static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
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{
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/* "mwait %eax,%ecx;" */
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asm volatile(
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"sti; .byte 0x0f,0x01,0xc9;"
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: :"a" (eax), "c" (ecx));
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}
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extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
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#define stack_current() \
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