1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _LINUX_SCHED_RCUPDATE_WAIT_H 3 #define _LINUX_SCHED_RCUPDATE_WAIT_H 4 5 /* 6 * RCU synchronization types and methods: 7 */ 8 9 #include <linux/rcupdate.h> 10 #include <linux/completion.h> 11 #include <linux/sched.h> 12 13 /* 14 * Structure allowing asynchronous waiting on RCU. 15 */ 16 struct rcu_synchronize { 17 struct rcu_head head; 18 struct completion completion; 19 20 /* This is for debugging. */ 21 struct rcu_gp_oldstate oldstate; 22 }; 23 void wakeme_after_rcu(struct rcu_head *head); 24 25 void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array, 26 struct rcu_synchronize *rs_array); 27 28 #define _wait_rcu_gp(checktiny, state, ...) \ 29 do { \ 30 call_rcu_func_t __crcu_array[] = { __VA_ARGS__ }; \ 31 struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)]; \ 32 __wait_rcu_gp(checktiny, state, ARRAY_SIZE(__crcu_array), __crcu_array, __rs_array); \ 33 } while (0) 34 35 #define wait_rcu_gp(...) _wait_rcu_gp(false, TASK_UNINTERRUPTIBLE, __VA_ARGS__) 36 #define wait_rcu_gp_state(state, ...) _wait_rcu_gp(false, state, __VA_ARGS__) 37 38 /** 39 * synchronize_rcu_mult - Wait concurrently for multiple grace periods 40 * @...: List of call_rcu() functions for different grace periods to wait on 41 * 42 * This macro waits concurrently for multiple types of RCU grace periods. 43 * For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait 44 * on concurrent RCU and RCU-tasks grace periods. Waiting on a given SRCU 45 * domain requires you to write a wrapper function for that SRCU domain's 46 * call_srcu() function, with this wrapper supplying the pointer to the 47 * corresponding srcu_struct. 48 * 49 * Note that call_rcu_hurry() should be used instead of call_rcu() 50 * because in kernels built with CONFIG_RCU_LAZY=y the delay between the 51 * invocation of call_rcu() and that of the corresponding RCU callback 52 * can be multiple seconds. 53 * 54 * The first argument tells Tiny RCU's _wait_rcu_gp() not to 55 * bother waiting for RCU. The reason for this is because anywhere 56 * synchronize_rcu_mult() can be called is automatically already a full 57 * grace period. 58 */ 59 #define synchronize_rcu_mult(...) \ 60 _wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), TASK_UNINTERRUPTIBLE, __VA_ARGS__) 61 62 static inline void cond_resched_rcu(void) 63 { 64 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU) 65 rcu_read_unlock(); 66 cond_resched(); 67 rcu_read_lock(); 68 #endif 69 } 70 71 // Has the current task blocked within its current RCU read-side 72 // critical section? 73 static inline bool has_rcu_reader_blocked(void) 74 { 75 #ifdef CONFIG_PREEMPT_RCU 76 return !list_empty(¤t->rcu_node_entry); 77 #else 78 return false; 79 #endif 80 } 81 82 #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */ 83