--- zzzz-none-000/linux-3.10.107/include/linux/preempt.h 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/include/linux/preempt.h 2021-02-04 17:41:59.000000000 +0000 @@ -6,105 +6,205 @@ * preempt_count (used for kernel preemption, interrupt count, etc.) */ -#include #include #include -#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) - extern void add_preempt_count(int val); - extern void sub_preempt_count(int val); -#else -# define add_preempt_count(val) do { preempt_count() += (val); } while (0) -# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0) -#endif +/* + * We put the hardirq and softirq counter into the preemption + * counter. The bitmask has the following meaning: + * + * - bits 0-7 are the preemption count (max preemption depth: 256) + * - bits 8-15 are the softirq count (max # of softirqs: 256) + * + * The hardirq count could in theory be the same as the number of + * interrupts in the system, but we run all interrupt handlers with + * interrupts disabled, so we cannot have nesting interrupts. Though + * there are a few palaeontologic drivers which reenable interrupts in + * the handler, so we need more than one bit here. + * + * PREEMPT_MASK: 0x000000ff + * SOFTIRQ_MASK: 0x0000ff00 + * HARDIRQ_MASK: 0x000f0000 + * NMI_MASK: 0x00100000 + * PREEMPT_NEED_RESCHED: 0x80000000 + */ +#define PREEMPT_BITS 8 +#define SOFTIRQ_BITS 8 +#define HARDIRQ_BITS 4 +#define NMI_BITS 1 + +#define PREEMPT_SHIFT 0 +#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS) +#define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS) +#define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS) + +#define __IRQ_MASK(x) ((1UL << (x))-1) + +#define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT) +#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT) +#define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT) +#define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT) + +#define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT) +#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT) +#define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT) +#define NMI_OFFSET (1UL << NMI_SHIFT) + +#define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET) + +/* We use the MSB mostly because its available */ +#define PREEMPT_NEED_RESCHED 0x80000000 + +/* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */ +#include + +#define hardirq_count() (preempt_count() & HARDIRQ_MASK) +#define softirq_count() (preempt_count() & SOFTIRQ_MASK) +#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \ + | NMI_MASK)) -#define inc_preempt_count() add_preempt_count(1) -#define dec_preempt_count() sub_preempt_count(1) +/* + * Are we doing bottom half or hardware interrupt processing? + * Are we in a softirq context? Interrupt context? + * in_softirq - Are we currently processing softirq or have bh disabled? + * in_serving_softirq - Are we currently processing softirq? + */ +#define in_irq() (hardirq_count()) +#define in_softirq() (softirq_count()) +#define in_interrupt() (irq_count()) +#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) -#define preempt_count() (current_thread_info()->preempt_count) +/* + * Are we in NMI context? + */ +#define in_nmi() (preempt_count() & NMI_MASK) -#ifdef CONFIG_PREEMPT +/* + * The preempt_count offset after preempt_disable(); + */ +#if defined(CONFIG_PREEMPT_COUNT) +# define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET +#else +# define PREEMPT_DISABLE_OFFSET 0 +#endif -asmlinkage void preempt_schedule(void); +/* + * The preempt_count offset after spin_lock() + */ +#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET -#define preempt_check_resched() \ -do { \ - if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ - preempt_schedule(); \ -} while (0) +/* + * The preempt_count offset needed for things like: + * + * spin_lock_bh() + * + * Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and + * softirqs, such that unlock sequences of: + * + * spin_unlock(); + * local_bh_enable(); + * + * Work as expected. + */ +#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET) -#ifdef CONFIG_CONTEXT_TRACKING +/* + * Are we running in atomic context? WARNING: this macro cannot + * always detect atomic context; in particular, it cannot know about + * held spinlocks in non-preemptible kernels. Thus it should not be + * used in the general case to determine whether sleeping is possible. + * Do not use in_atomic() in driver code. + */ +#define in_atomic() (preempt_count() != 0) -void preempt_schedule_context(void); +/* + * Check whether we were atomic before we did preempt_disable(): + * (used by the scheduler) + */ +#define in_atomic_preempt_off() (preempt_count() != PREEMPT_DISABLE_OFFSET) -#define preempt_check_resched_context() \ -do { \ - if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ - preempt_schedule_context(); \ -} while (0) +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) +extern void preempt_count_add(int val); +extern void preempt_count_sub(int val); +#define preempt_count_dec_and_test() \ + ({ preempt_count_sub(1); should_resched(0); }) #else +#define preempt_count_add(val) __preempt_count_add(val) +#define preempt_count_sub(val) __preempt_count_sub(val) +#define preempt_count_dec_and_test() __preempt_count_dec_and_test() +#endif -#define preempt_check_resched_context() preempt_check_resched() - -#endif /* CONFIG_CONTEXT_TRACKING */ - -#else /* !CONFIG_PREEMPT */ - -#define preempt_check_resched() do { } while (0) -#define preempt_check_resched_context() do { } while (0) - -#endif /* CONFIG_PREEMPT */ +#define __preempt_count_inc() __preempt_count_add(1) +#define __preempt_count_dec() __preempt_count_sub(1) +#define preempt_count_inc() preempt_count_add(1) +#define preempt_count_dec() preempt_count_sub(1) #ifdef CONFIG_PREEMPT_COUNT #define preempt_disable() \ do { \ - inc_preempt_count(); \ + preempt_count_inc(); \ barrier(); \ } while (0) #define sched_preempt_enable_no_resched() \ do { \ barrier(); \ - dec_preempt_count(); \ + preempt_count_dec(); \ } while (0) -#define preempt_enable_no_resched() sched_preempt_enable_no_resched() +#define preempt_enable_no_resched() sched_preempt_enable_no_resched() + +#define preemptible() (preempt_count() == 0 && !irqs_disabled()) +#ifdef CONFIG_PREEMPT #define preempt_enable() \ do { \ - preempt_enable_no_resched(); \ barrier(); \ - preempt_check_resched(); \ + if (unlikely(preempt_count_dec_and_test())) \ + __preempt_schedule(); \ } while (0) -/* For debugging and tracer internals only! */ -#define add_preempt_count_notrace(val) \ - do { preempt_count() += (val); } while (0) -#define sub_preempt_count_notrace(val) \ - do { preempt_count() -= (val); } while (0) -#define inc_preempt_count_notrace() add_preempt_count_notrace(1) -#define dec_preempt_count_notrace() sub_preempt_count_notrace(1) - -#define preempt_disable_notrace() \ +#define preempt_enable_notrace() \ do { \ - inc_preempt_count_notrace(); \ barrier(); \ + if (unlikely(__preempt_count_dec_and_test())) \ + __preempt_schedule_notrace(); \ } while (0) -#define preempt_enable_no_resched_notrace() \ +#define preempt_check_resched() \ +do { \ + if (should_resched(0)) \ + __preempt_schedule(); \ +} while (0) + +#else /* !CONFIG_PREEMPT */ +#define preempt_enable() \ do { \ barrier(); \ - dec_preempt_count_notrace(); \ + preempt_count_dec(); \ } while (0) -/* preempt_check_resched is OK to trace */ #define preempt_enable_notrace() \ do { \ - preempt_enable_no_resched_notrace(); \ barrier(); \ - preempt_check_resched_context(); \ + __preempt_count_dec(); \ +} while (0) + +#define preempt_check_resched() do { } while (0) +#endif /* CONFIG_PREEMPT */ + +#define preempt_disable_notrace() \ +do { \ + __preempt_count_inc(); \ + barrier(); \ +} while (0) + +#define preempt_enable_no_resched_notrace() \ +do { \ + barrier(); \ + __preempt_count_dec(); \ } while (0) #else /* !CONFIG_PREEMPT_COUNT */ @@ -115,17 +215,39 @@ * that can cause faults and scheduling migrate into our preempt-protected * region. */ -#define preempt_disable() barrier() +#define preempt_disable() barrier() #define sched_preempt_enable_no_resched() barrier() -#define preempt_enable_no_resched() barrier() -#define preempt_enable() barrier() +#define preempt_enable_no_resched() barrier() +#define preempt_enable() barrier() +#define preempt_check_resched() do { } while (0) #define preempt_disable_notrace() barrier() #define preempt_enable_no_resched_notrace() barrier() #define preempt_enable_notrace() barrier() +#define preemptible() 0 #endif /* CONFIG_PREEMPT_COUNT */ +#ifdef MODULE +/* + * Modules have no business playing preemption tricks. + */ +#undef sched_preempt_enable_no_resched +#undef preempt_enable_no_resched +#undef preempt_enable_no_resched_notrace +#undef preempt_check_resched +#endif + +#define preempt_set_need_resched() \ +do { \ + set_preempt_need_resched(); \ +} while (0) +#define preempt_fold_need_resched() \ +do { \ + if (tif_need_resched()) \ + set_preempt_need_resched(); \ +} while (0) + #ifdef CONFIG_PREEMPT_NOTIFIERS struct preempt_notifier; @@ -162,6 +284,8 @@ struct preempt_ops *ops; }; +void preempt_notifier_inc(void); +void preempt_notifier_dec(void); void preempt_notifier_register(struct preempt_notifier *notifier); void preempt_notifier_unregister(struct preempt_notifier *notifier);