rcu.h 4.4 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
/*
 * Read-Copy Update definitions shared among RCU implementations.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright IBM Corporation, 2011
 *
 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 */

#ifndef __LINUX_RCU_H
#define __LINUX_RCU_H

26 27 28 29 30 31
#ifdef CONFIG_RCU_TRACE
#define RCU_TRACE(stmt) stmt
#else /* #ifdef CONFIG_RCU_TRACE */
#define RCU_TRACE(stmt)
#endif /* #else #ifdef CONFIG_RCU_TRACE */

32 33 34 35
/*
 * Process-level increment to ->dynticks_nesting field.  This allows for
 * architectures that use half-interrupts and half-exceptions from
 * process context.
36 37 38 39 40 41 42 43 44 45 46 47 48
 *
 * DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH
 * that counts the number of process-based reasons why RCU cannot
 * consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE
 * is the value used to increment or decrement this field.
 *
 * The rest of the bits could in principle be used to count interrupts,
 * but this would mean that a negative-one value in the interrupt
 * field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field.
 * We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK
 * that is set to DYNTICK_TASK_FLAG upon initial exit from idle.
 * The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon
 * initial exit from idle.
49
 */
50 51 52 53 54 55 56
#define DYNTICK_TASK_NEST_WIDTH 7
#define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1)
#define DYNTICK_TASK_NEST_MASK  (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1)
#define DYNTICK_TASK_FLAG	   ((DYNTICK_TASK_NEST_VALUE / 8) * 2)
#define DYNTICK_TASK_MASK	   ((DYNTICK_TASK_NEST_VALUE / 8) * 3)
#define DYNTICK_TASK_EXIT_IDLE	   (DYNTICK_TASK_NEST_VALUE + \
				    DYNTICK_TASK_FLAG)
57

58 59 60 61 62 63 64 65 66 67 68 69
/*
 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
 * by call_rcu() and rcu callback execution, and are therefore not part of the
 * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors.
 */

#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
# define STATE_RCU_HEAD_READY	0
# define STATE_RCU_HEAD_QUEUED	1

extern struct debug_obj_descr rcuhead_debug_descr;

70
static inline int debug_rcu_head_queue(struct rcu_head *head)
71
{
72 73 74
	int r1;

	r1 = debug_object_activate(head, &rcuhead_debug_descr);
75 76 77
	debug_object_active_state(head, &rcuhead_debug_descr,
				  STATE_RCU_HEAD_READY,
				  STATE_RCU_HEAD_QUEUED);
78
	return r1;
79 80 81 82 83 84 85 86 87 88
}

static inline void debug_rcu_head_unqueue(struct rcu_head *head)
{
	debug_object_active_state(head, &rcuhead_debug_descr,
				  STATE_RCU_HEAD_QUEUED,
				  STATE_RCU_HEAD_READY);
	debug_object_deactivate(head, &rcuhead_debug_descr);
}
#else	/* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
89
static inline int debug_rcu_head_queue(struct rcu_head *head)
90
{
91
	return 0;
92 93 94 95 96 97 98
}

static inline void debug_rcu_head_unqueue(struct rcu_head *head)
{
}
#endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */

99
void kfree(const void *);
100

101
static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head)
102 103 104
{
	unsigned long offset = (unsigned long)head->func;

105
	rcu_lock_acquire(&rcu_callback_map);
106
	if (__is_kfree_rcu_offset(offset)) {
107
		RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset));
108
		kfree((void *)head - offset);
109
		rcu_lock_release(&rcu_callback_map);
110
		return 1;
111
	} else {
112
		RCU_TRACE(trace_rcu_invoke_callback(rn, head));
113
		head->func(head);
114
		rcu_lock_release(&rcu_callback_map);
115
		return 0;
116 117 118
	}
}

119 120
extern int rcu_expedited;

121 122 123 124 125 126 127
#ifdef CONFIG_RCU_STALL_COMMON

extern int rcu_cpu_stall_suppress;
int rcu_jiffies_till_stall_check(void);

#endif /* #ifdef CONFIG_RCU_STALL_COMMON */

128 129 130 131 132 133 134
/*
 * Strings used in tracepoints need to be exported via the
 * tracing system such that tools like perf and trace-cmd can
 * translate the string address pointers to actual text.
 */
#define TPS(x)  tracepoint_string(x)

135
#endif /* __LINUX_RCU_H */