1 /* 2 * Read-Copy Update definitions shared among RCU implementations. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17 * 18 * Copyright IBM Corporation, 2011 19 * 20 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 21 */ 22 23 #ifndef __LINUX_RCU_H 24 #define __LINUX_RCU_H 25 26 #ifdef CONFIG_RCU_TRACE 27 #define RCU_TRACE(stmt) stmt 28 #else /* #ifdef CONFIG_RCU_TRACE */ 29 #define RCU_TRACE(stmt) 30 #endif /* #else #ifdef CONFIG_RCU_TRACE */ 31 32 /* 33 * Process-level increment to ->dynticks_nesting field. This allows for 34 * architectures that use half-interrupts and half-exceptions from 35 * process context. 36 * 37 * DYNTICK_TASK_NEST_MASK defines a field of width DYNTICK_TASK_NEST_WIDTH 38 * that counts the number of process-based reasons why RCU cannot 39 * consider the corresponding CPU to be idle, and DYNTICK_TASK_NEST_VALUE 40 * is the value used to increment or decrement this field. 41 * 42 * The rest of the bits could in principle be used to count interrupts, 43 * but this would mean that a negative-one value in the interrupt 44 * field could incorrectly zero out the DYNTICK_TASK_NEST_MASK field. 45 * We therefore provide a two-bit guard field defined by DYNTICK_TASK_MASK 46 * that is set to DYNTICK_TASK_FLAG upon initial exit from idle. 47 * The DYNTICK_TASK_EXIT_IDLE value is thus the combined value used upon 48 * initial exit from idle. 49 */ 50 #define DYNTICK_TASK_NEST_WIDTH 7 51 #define DYNTICK_TASK_NEST_VALUE ((LLONG_MAX >> DYNTICK_TASK_NEST_WIDTH) + 1) 52 #define DYNTICK_TASK_NEST_MASK (LLONG_MAX - DYNTICK_TASK_NEST_VALUE + 1) 53 #define DYNTICK_TASK_FLAG ((DYNTICK_TASK_NEST_VALUE / 8) * 2) 54 #define DYNTICK_TASK_MASK ((DYNTICK_TASK_NEST_VALUE / 8) * 3) 55 #define DYNTICK_TASK_EXIT_IDLE (DYNTICK_TASK_NEST_VALUE + \ 56 DYNTICK_TASK_FLAG) 57 58 /* 59 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally 60 * by call_rcu() and rcu callback execution, and are therefore not part of the 61 * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors. 62 */ 63 64 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 65 # define STATE_RCU_HEAD_READY 0 66 # define STATE_RCU_HEAD_QUEUED 1 67 68 extern struct debug_obj_descr rcuhead_debug_descr; 69 70 static inline int debug_rcu_head_queue(struct rcu_head *head) 71 { 72 int r1; 73 74 r1 = debug_object_activate(head, &rcuhead_debug_descr); 75 debug_object_active_state(head, &rcuhead_debug_descr, 76 STATE_RCU_HEAD_READY, 77 STATE_RCU_HEAD_QUEUED); 78 return r1; 79 } 80 81 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 82 { 83 debug_object_active_state(head, &rcuhead_debug_descr, 84 STATE_RCU_HEAD_QUEUED, 85 STATE_RCU_HEAD_READY); 86 debug_object_deactivate(head, &rcuhead_debug_descr); 87 } 88 #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 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 95 { 96 } 97 #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 98 99 extern void kfree(const void *); 100 101 static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) 102 { 103 unsigned long offset = (unsigned long)head->func; 104 105 if (__is_kfree_rcu_offset(offset)) { 106 RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset)); 107 kfree((void *)head - offset); 108 return 1; 109 } else { 110 RCU_TRACE(trace_rcu_invoke_callback(rn, head)); 111 head->func(head); 112 return 0; 113 } 114 } 115 116 extern int rcu_expedited; 117 118 #ifdef CONFIG_RCU_STALL_COMMON 119 120 extern int rcu_cpu_stall_suppress; 121 int rcu_jiffies_till_stall_check(void); 122 123 #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ 124 125 /* 126 * Strings used in tracepoints need to be exported via the 127 * tracing system such that tools like perf and trace-cmd can 128 * translate the string address pointers to actual text. 129 */ 130 #define TPS(x) tracepoint_string(x) 131 132 #endif /* __LINUX_RCU_H */ 133