1 #ifndef __LINUX_PREEMPT_H 2 #define __LINUX_PREEMPT_H 3 4 /* 5 * include/linux/preempt.h - macros for accessing and manipulating 6 * preempt_count (used for kernel preemption, interrupt count, etc.) 7 */ 8 9 #include <linux/thread_info.h> 10 #include <linux/linkage.h> 11 #include <linux/list.h> 12 13 #ifdef CONFIG_DEBUG_PREEMPT 14 extern void fastcall add_preempt_count(int val); 15 extern void fastcall sub_preempt_count(int val); 16 #else 17 # define add_preempt_count(val) do { preempt_count() += (val); } while (0) 18 # define sub_preempt_count(val) do { preempt_count() -= (val); } while (0) 19 #endif 20 21 #define inc_preempt_count() add_preempt_count(1) 22 #define dec_preempt_count() sub_preempt_count(1) 23 24 #define preempt_count() (current_thread_info()->preempt_count) 25 26 #ifdef CONFIG_PREEMPT 27 28 asmlinkage void preempt_schedule(void); 29 30 #define preempt_disable() \ 31 do { \ 32 inc_preempt_count(); \ 33 barrier(); \ 34 } while (0) 35 36 #define preempt_enable_no_resched() \ 37 do { \ 38 barrier(); \ 39 dec_preempt_count(); \ 40 } while (0) 41 42 #define preempt_check_resched() \ 43 do { \ 44 if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ 45 preempt_schedule(); \ 46 } while (0) 47 48 #define preempt_enable() \ 49 do { \ 50 preempt_enable_no_resched(); \ 51 barrier(); \ 52 preempt_check_resched(); \ 53 } while (0) 54 55 #else 56 57 #define preempt_disable() do { } while (0) 58 #define preempt_enable_no_resched() do { } while (0) 59 #define preempt_enable() do { } while (0) 60 #define preempt_check_resched() do { } while (0) 61 62 #endif 63 64 #ifdef CONFIG_PREEMPT_NOTIFIERS 65 66 struct preempt_notifier; 67 68 /** 69 * preempt_ops - notifiers called when a task is preempted and rescheduled 70 * @sched_in: we're about to be rescheduled: 71 * notifier: struct preempt_notifier for the task being scheduled 72 * cpu: cpu we're scheduled on 73 * @sched_out: we've just been preempted 74 * notifier: struct preempt_notifier for the task being preempted 75 * next: the task that's kicking us out 76 */ 77 struct preempt_ops { 78 void (*sched_in)(struct preempt_notifier *notifier, int cpu); 79 void (*sched_out)(struct preempt_notifier *notifier, 80 struct task_struct *next); 81 }; 82 83 /** 84 * preempt_notifier - key for installing preemption notifiers 85 * @link: internal use 86 * @ops: defines the notifier functions to be called 87 * 88 * Usually used in conjunction with container_of(). 89 */ 90 struct preempt_notifier { 91 struct hlist_node link; 92 struct preempt_ops *ops; 93 }; 94 95 void preempt_notifier_register(struct preempt_notifier *notifier); 96 void preempt_notifier_unregister(struct preempt_notifier *notifier); 97 98 static inline void preempt_notifier_init(struct preempt_notifier *notifier, 99 struct preempt_ops *ops) 100 { 101 INIT_HLIST_NODE(¬ifier->link); 102 notifier->ops = ops; 103 } 104 105 #endif 106 107 #endif /* __LINUX_PREEMPT_H */ 108