101 lines
3.1 KiB
C
101 lines
3.1 KiB
C
/* 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 + nesting);
|
|
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 */
|