| 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 void debug_rcu_head_queue(struct rcu_head *head) |
| 71 | { |
| 72 | debug_object_activate(head, &rcuhead_debug_descr); |
| 73 | debug_object_active_state(head, &rcuhead_debug_descr, |
| 74 | STATE_RCU_HEAD_READY, |
| 75 | STATE_RCU_HEAD_QUEUED); |
| 76 | } |
| 77 | |
| 78 | static inline void debug_rcu_head_unqueue(struct rcu_head *head) |
| 79 | { |
| 80 | debug_object_active_state(head, &rcuhead_debug_descr, |
| 81 | STATE_RCU_HEAD_QUEUED, |
| 82 | STATE_RCU_HEAD_READY); |
| 83 | debug_object_deactivate(head, &rcuhead_debug_descr); |
| 84 | } |
| 85 | #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ |
| 86 | static inline void debug_rcu_head_queue(struct rcu_head *head) |
| 87 | { |
| 88 | } |
| 89 | |
| 90 | static inline void debug_rcu_head_unqueue(struct rcu_head *head) |
| 91 | { |
| 92 | } |
| 93 | #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ |
| 94 | |
| 95 | extern void kfree(const void *); |
| 96 | |
| 97 | static inline bool __rcu_reclaim(char *rn, struct rcu_head *head) |
| 98 | { |
| 99 | unsigned long offset = (unsigned long)head->func; |
| 100 | |
| 101 | if (__is_kfree_rcu_offset(offset)) { |
| 102 | RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset)); |
| 103 | kfree((void *)head - offset); |
| 104 | return 1; |
| 105 | } else { |
| 106 | RCU_TRACE(trace_rcu_invoke_callback(rn, head)); |
| 107 | head->func(head); |
| 108 | return 0; |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | #endif /* __LINUX_RCU_H */ |