include/linux/rcutiny.h

0001 /* SPDX-License-Identifier: GPL-2.0+ */
0002 /*
0003  * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
0004  *
0005  * Copyright IBM Corporation, 2008
0006  *
0007  * Author: Paul E. McKenney <paulmck@linux.ibm.com>
0008  *
0009  * For detailed explanation of Read-Copy Update mechanism see -
0010  *      Documentation/RCU
0011  */
0012 #ifndef __LINUX_TINY_H
0013 #define __LINUX_TINY_H
0014
0015 #include <asm/param.h> /* for HZ */
0016
0017 unsigned long get_state_synchronize_rcu(void);
0018 unsigned long start_poll_synchronize_rcu(void);
0019 bool poll_state_synchronize_rcu(unsigned long oldstate);
0020
0021 static inline void cond_synchronize_rcu(unsigned long oldstate)
0022 {
0023     might_sleep();
0024 }
0025
0026 static inline unsigned long start_poll_synchronize_rcu_expedited(void)
0027 {
0028     return start_poll_synchronize_rcu();
0029 }
0030
0031 static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
0032 {
0033     cond_synchronize_rcu(oldstate);
0034 }
0035
0036 extern void rcu_barrier(void);
0037
0038 static inline void synchronize_rcu_expedited(void)
0039 {
0040     synchronize_rcu();
0041 }
0042
0043 /*
0044  * Add one more declaration of kvfree() here. It is
0045  * not so straight forward to just include <linux/mm.h>
0046  * where it is defined due to getting many compile
0047  * errors caused by that include.
0048  */
0049 extern void kvfree(const void *addr);
0050
0051 static inline void __kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
0052 {
0053     if (head) {
0054         call_rcu(head, func);
0055         return;
0056     }
0057
0058     // kvfree_rcu(one_arg) call.
0059     might_sleep();
0060     synchronize_rcu();
0061     kvfree((void *) func);
0062 }
0063
0064 #ifdef CONFIG_KASAN_GENERIC
0065 void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
0066 #else
0067 static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
0068 {
0069     __kvfree_call_rcu(head, func);
0070 }
0071 #endif
0072
0073 void rcu_qs(void);
0074
0075 static inline void rcu_softirq_qs(void)
0076 {
0077     rcu_qs();
0078 }
0079
0080 #define rcu_note_context_switch(preempt) \
0081     do { \
0082         rcu_qs(); \
0083         rcu_tasks_qs(current, (preempt)); \
0084     } while (0)
0085
0086 static inline int rcu_needs_cpu(void)
0087 {
0088     return 0;
0089 }
0090
0091 /*
0092  * Take advantage of the fact that there is only one CPU, which
0093  * allows us to ignore virtualization-based context switches.
0094  */
0095 static inline void rcu_virt_note_context_switch(int cpu) { }
0096 static inline void rcu_cpu_stall_reset(void) { }
0097 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
0098 static inline void rcu_irq_exit_check_preempt(void) { }
0099 #define rcu_is_idle_cpu(cpu) \
0100     (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq())
0101 static inline void exit_rcu(void) { }
0102 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
0103 {
0104     return false;
0105 }
0106 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
0107 #ifdef CONFIG_SRCU
0108 void rcu_scheduler_starting(void);
0109 #else /* #ifndef CONFIG_SRCU */
0110 static inline void rcu_scheduler_starting(void) { }
0111 #endif /* #else #ifndef CONFIG_SRCU */
0112 static inline void rcu_end_inkernel_boot(void) { }
0113 static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
0114 static inline bool rcu_is_watching(void) { return true; }
0115 static inline void rcu_momentary_dyntick_idle(void) { }
0116 static inline void kfree_rcu_scheduler_running(void) { }
0117 static inline bool rcu_gp_might_be_stalled(void) { return false; }
0118
0119 /* Avoid RCU read-side critical sections leaking across. */
0120 static inline void rcu_all_qs(void) { barrier(); }
0121
0122 /* RCUtree hotplug events */
0123 #define rcutree_prepare_cpu      NULL
0124 #define rcutree_online_cpu       NULL
0125 #define rcutree_offline_cpu      NULL
0126 #define rcutree_dead_cpu         NULL
0127 #define rcutree_dying_cpu        NULL
0128 static inline void rcu_cpu_starting(unsigned int cpu) { }
0129
0130 #endif /* __LINUX_RCUTINY_H */