| /* SPDX-License-Identifier: GPL-2.0+ */ |
| /* |
| * Read-Copy Update mechanism for mutual exclusion, adapted for tracing. |
| * |
| * Copyright (C) 2020 Paul E. McKenney. |
| */ |
| |
| #ifndef __LINUX_RCUPDATE_TRACE_H |
| #define __LINUX_RCUPDATE_TRACE_H |
| |
| #include <linux/sched.h> |
| #include <linux/rcupdate.h> |
| |
| extern struct lockdep_map rcu_trace_lock_map; |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| |
| static inline int rcu_read_lock_trace_held(void) |
| { |
| return lock_is_held(&rcu_trace_lock_map); |
| } |
| |
| #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
| |
| static inline int rcu_read_lock_trace_held(void) |
| { |
| return 1; |
| } |
| |
| #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
| |
| #ifdef CONFIG_TASKS_TRACE_RCU |
| |
| void rcu_read_unlock_trace_special(struct task_struct *t); |
| |
| /** |
| * rcu_read_lock_trace - mark beginning of RCU-trace read-side critical section |
| * |
| * When synchronize_rcu_tasks_trace() is invoked by one task, then that |
| * task is guaranteed to block until all other tasks exit their read-side |
| * critical sections. Similarly, if call_rcu_trace() is invoked on one |
| * task while other tasks are within RCU read-side critical sections, |
| * invocation of the corresponding RCU callback is deferred until after |
| * the all the other tasks exit their critical sections. |
| * |
| * For more details, please see the documentation for rcu_read_lock(). |
| */ |
| static inline void rcu_read_lock_trace(void) |
| { |
| struct task_struct *t = current; |
| |
| WRITE_ONCE(t->trc_reader_nesting, READ_ONCE(t->trc_reader_nesting) + 1); |
| barrier(); |
| if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB) && |
| t->trc_reader_special.b.need_mb) |
| smp_mb(); // Pairs with update-side barriers |
| rcu_lock_acquire(&rcu_trace_lock_map); |
| } |
| |
| /** |
| * rcu_read_unlock_trace - mark end of RCU-trace read-side critical section |
| * |
| * Pairs with a preceding call to rcu_read_lock_trace(), and nesting is |
| * allowed. Invoking a rcu_read_unlock_trace() when there is no matching |
| * rcu_read_lock_trace() is verboten, and will result in lockdep complaints. |
| * |
| * For more details, please see the documentation for rcu_read_unlock(). |
| */ |
| static inline void rcu_read_unlock_trace(void) |
| { |
| int nesting; |
| struct task_struct *t = current; |
| |
| rcu_lock_release(&rcu_trace_lock_map); |
| nesting = READ_ONCE(t->trc_reader_nesting) - 1; |
| barrier(); // Critical section before disabling. |
| // Disable IPI-based setting of .need_qs. |
| WRITE_ONCE(t->trc_reader_nesting, INT_MIN); |
| if (likely(!READ_ONCE(t->trc_reader_special.s)) || nesting) { |
| WRITE_ONCE(t->trc_reader_nesting, nesting); |
| return; // We assume shallow reader nesting. |
| } |
| WARN_ON_ONCE(nesting != 0); |
| rcu_read_unlock_trace_special(t); |
| } |
| |
| void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func); |
| void synchronize_rcu_tasks_trace(void); |
| void rcu_barrier_tasks_trace(void); |
| #else |
| /* |
| * The BPF JIT forms these addresses even when it doesn't call these |
| * functions, so provide definitions that result in runtime errors. |
| */ |
| static inline void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func) { BUG(); } |
| static inline void rcu_read_lock_trace(void) { BUG(); } |
| static inline void rcu_read_unlock_trace(void) { BUG(); } |
| #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */ |
| |
| #endif /* __LINUX_RCUPDATE_TRACE_H */ |