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1 | /* |
1 | /* |
2 | * Copyright (c) 2007 Jan Hudecek |
2 | * Copyright (c) 2007 Jan Hudecek |
3 | * Copyright (c) 2006 Jakub Jermar |
3 | * Copyright (c) 2006 Jakub Jermar |
4 | * All rights reserved. |
4 | * All rights reserved. |
5 | * |
5 | * |
6 | * Redistribution and use in source and binary forms, with or without |
6 | * Redistribution and use in source and binary forms, with or without |
7 | * modification, are permitted provided that the following conditions |
7 | * modification, are permitted provided that the following conditions |
8 | * are met: |
8 | * are met: |
9 | * |
9 | * |
10 | * - Redistributions of source code must retain the above copyright |
10 | * - Redistributions of source code must retain the above copyright |
11 | * notice, this list of conditions and the following disclaimer. |
11 | * notice, this list of conditions and the following disclaimer. |
12 | * - Redistributions in binary form must reproduce the above copyright |
12 | * - Redistributions in binary form must reproduce the above copyright |
13 | * notice, this list of conditions and the following disclaimer in the |
13 | * notice, this list of conditions and the following disclaimer in the |
14 | * documentation and/or other materials provided with the distribution. |
14 | * documentation and/or other materials provided with the distribution. |
15 | * - The name of the author may not be used to endorse or promote products |
15 | * - The name of the author may not be used to endorse or promote products |
16 | * derived from this software without specific prior written permission. |
16 | * derived from this software without specific prior written permission. |
17 | * |
17 | * |
18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
28 | */ |
28 | */ |
29 | /** @addtogroup sync |
29 | /** @addtogroup sync |
30 | * @{ |
30 | * @{ |
31 | */ |
31 | */ |
32 | /** @file |
32 | /** @file rcu.c |
- | 33 | * @brief RCU synchronization primitive |
|
33 | */ |
34 | */ |
34 | 35 | ||
35 | #include <synch/rcu.h> |
36 | #include <synch/rcu.h> |
36 | #include <synch/waitq.h> |
37 | #include <synch/waitq.h> |
37 | #include <arch.h> |
38 | #include <arch.h> |
38 | #include <config.h> |
39 | #include <config.h> |
39 | #include <arch/types.h> |
40 | #include <arch/types.h> |
40 | #include <proc/tasklet.h> |
41 | #include <proc/tasklet.h> |
41 | #include <synch/spinlock.h> |
42 | #include <synch/spinlock.h> |
42 | #include <time/delay.h> |
43 | #include <time/delay.h> |
43 | #include <panic.h> |
44 | #include <panic.h> |
44 | #include <print.h> |
45 | #include <print.h> |
45 | 46 | ||
46 | 47 | ||
47 | 48 | ||
48 | - | ||
- | 49 | /** Main data structure of the RCU implementation */ |
|
49 | typedef struct { |
50 | typedef struct { |
50 | #ifdef CONFIG_SMP |
51 | #ifdef CONFIG_SMP |
- | 52 | /** flags indicating whether the corresponding CPU has passed QS for this RCU batch */ |
|
51 | bool* cpu_mask; |
53 | bool* cpu_mask; |
52 | #endif |
54 | #endif |
- | 55 | /** RCU batch waiting for finishing of current batch, QS monitoring hasn't been started for this one */ |
|
- | 56 | rcu_callback_list_t* next_batch; |
|
- | 57 | /** RCU batch that waits for passing of QSs on all CPUs */ |
|
53 | rcu_callback_list_t* next_batch, *current_batch, *done_batch; |
58 | rcu_callback_list_t *current_batch; |
- | 59 | /** RCU batch that has passed all QSs and waits for invocation */ |
|
- | 60 | rcu_callback_list_t *done_batch; |
|
54 | } rcu_global_t; |
61 | } rcu_cpu_data_t; |
55 | 62 | ||
56 | /** An array of structures holding the callbacks and the progress of QS for each CPU*/ |
63 | /** An array of structures holding the callbacks and the progress of QS for each CPU*/ |
57 | rcu_global_t* rcu_global=NULL; |
64 | rcu_cpu_data_t* rcu_global=NULL; |
58 | /** reference to the RCU tasklet, for scheduling it */ |
65 | /** reference to the RCU tasklet, for scheduling it */ |
59 | tasklet_descriptor_t* rcu_tasklet_desc; |
66 | tasklet_descriptor_t* rcu_tasklet_desc; |
60 | 67 | ||
61 | 68 | ||
62 | /** |
69 | /** |
63 | * Initializes data structures needed for RCU |
70 | * Initializes data structures needed for RCU |
64 | */ |
71 | */ |
65 | void rcu_init(void) |
72 | void rcu_init(void) |
66 | { |
73 | { |
67 | #ifdef CONFIG_SMP |
74 | #ifdef CONFIG_SMP |
68 | int i,j; |
75 | int i,j; |
69 | #endif |
76 | #endif |
70 | 77 | ||
71 | rcu_global = malloc(sizeof(rcu_global_t)*(config.cpu_count),0); |
78 | rcu_global = malloc(sizeof(rcu_cpu_data_t)*(config.cpu_count),0); |
72 | rcu_tasklet_desc = tasklet_register(&rcu_tasklet, NULL); |
79 | rcu_tasklet_desc = tasklet_register(&rcu_tasklet, NULL); |
73 | 80 | ||
74 | #ifdef CONFIG_SMP |
81 | #ifdef CONFIG_SMP |
75 | /* |
82 | /* |
76 | * Note: I allocate the array for a case when every CPU connected will be active |
83 | * Note: I allocate the array for a case when every CPU connected will be active |
77 | * In a case when there will be some inactive CPUs, I will use just the first cells. |
84 | * In a case when there will be some inactive CPUs, I will use just the active ones |
78 | */ |
85 | */ |
79 | for (i=0;i<config.cpu_count;i++) { |
86 | for (i=0;i<config.cpu_count;i++) { |
80 | rcu_global[i].done_batch = NULL; |
87 | rcu_global[i].done_batch = NULL; |
81 | rcu_global[i].current_batch = NULL; |
88 | rcu_global[i].current_batch = NULL; |
82 | rcu_global[i].next_batch = NULL; |
89 | rcu_global[i].next_batch = NULL; |
83 | rcu_global[i].cpu_mask = malloc(sizeof(bool)*config.cpu_count,0); |
90 | rcu_global[i].cpu_mask = malloc(sizeof(bool)*config.cpu_count,0); |
84 | for (j=0;j<config.cpu_count;j++) { |
91 | for (j=0;j<config.cpu_count;j++) { |
85 | rcu_global[i].cpu_mask[j]=false; |
92 | rcu_global[i].cpu_mask[j]=false; |
86 | } |
93 | } |
87 | } |
94 | } |
88 | #else |
95 | #else |
89 | rcu_global[CPU->id].done_batch = NULL; |
96 | rcu_global[CPU->id].done_batch = NULL; |
90 | rcu_global[CPU->id].current_batch = NULL; |
97 | rcu_global[CPU->id].current_batch = NULL; |
91 | rcu_global[CPU->id].next_batch = NULL; |
98 | rcu_global[CPU->id].next_batch = NULL; |
92 | #endif |
99 | #endif |
93 | } |
100 | } |
94 | 101 | ||
95 | 102 | ||
96 | /** |
103 | /** |
97 | * Blocks until the grace period elapses |
104 | * Blocks until the grace period elapses |
98 | */ |
105 | */ |
99 | void rcu_synchronize(void) |
106 | void rcu_synchronize(void) |
100 | { |
107 | { |
101 | #ifdef CONFIG_SMP |
108 | #ifdef CONFIG_SMP |
102 | waitq_t wq; |
109 | waitq_t wq; |
103 | waitq_initialize(&wq); |
110 | waitq_initialize(&wq); |
104 | rcu_sync_callback_normal_alloc(&rcu_synchronize_callback_function, &wq); |
111 | rcu_sync_callback_normal_alloc(&rcu_synchronize_callback_function, &wq); |
105 | //sleep until the end of the grace period |
112 | //sleep until the end of the grace period |
106 | waitq_sleep(&wq); |
113 | waitq_sleep(&wq); |
107 | #endif |
114 | #endif |
108 | } |
115 | } |
109 | 116 | ||
110 | #ifdef CONFIG_SMP |
117 | #ifdef CONFIG_SMP |
111 | /** |
118 | /** |
112 | * Just a wakeup for waking up rcu_synchronize when the grace period has elapsed |
119 | * Just a wakeup for waking up rcu_synchronize when the grace period has elapsed |
113 | */ |
120 | */ |
114 | void rcu_synchronize_callback_function(void* waitq) |
121 | void rcu_synchronize_callback_function(void* waitq) |
115 | { |
122 | { |
116 | waitq_wakeup(((waitq_t*)waitq), WAKEUP_ALL); |
123 | waitq_wakeup(((waitq_t*)waitq), WAKEUP_ALL); |
117 | } |
124 | } |
118 | #endif |
125 | #endif |
119 | 126 | ||
120 | 127 | ||
121 | /** |
128 | /** |
122 | * appends this callback func to the queue of waiting callbacks, the rest |
129 | * Appends this callback func to the queue of waiting callbacks, the rest |
123 | * is handled in rcu_run_callbacks and in the tasklet. This is a lock free variant, |
130 | * is handled in rcu_run_callbacks and in the tasklet. This is a lock free variant, |
124 | * which must be supplied with a preallocated rcu_callback_list_t structure |
131 | * which must be supplied with a preallocated rcu_callback_list_t structure |
- | 132 | * which is deallocated after the callback is called |
|
125 | */ |
133 | */ |
126 | void rcu_sync_callback(void (*func)(void* data), void* data, rcu_callback_list_t* rd) |
134 | void rcu_sync_callback(void (*func)(void* data), void* data, rcu_callback_list_t* rd) |
127 | { |
135 | { |
128 | #ifndef CONFIG_SMP |
136 | #ifndef CONFIG_SMP |
129 | func(data); |
137 | func(data); |
130 | #else |
138 | #else |
131 | 139 | ||
132 | ipl_t ipl; |
140 | ipl_t ipl; |
133 | rd->func = func; |
141 | rd->func = func; |
134 | rd->data = data; |
142 | rd->data = data; |
135 | 143 | ||
- | 144 | //disabling interrupts removes need for any synchronization - the list of callbacks is |
|
- | 145 | //always accessed only on current CPU |
|
136 | ipl = interrupts_disable(); |
146 | ipl = interrupts_disable(); |
137 | //append to the list of callbacks waiting for their batch to begin |
147 | //append to the list of callbacks waiting for their batch to begin |
138 | rd->next = rcu_global[CPU->id].next_batch; |
148 | rd->next = rcu_global[CPU->id].next_batch; |
139 | rcu_global[CPU->id].next_batch = rd; |
149 | rcu_global[CPU->id].next_batch = rd; |
140 | interrupts_restore(ipl); |
- | |
141 | - | ||
142 | rcu_passQS(); |
150 | rcu_passQS(); |
- | 151 | interrupts_restore(ipl); |
|
143 | #endif |
152 | #endif |
144 | } |
153 | } |
145 | 154 | ||
146 | /** |
155 | /** |
147 | * RCU tasklet, tests passing through QSs, moves from current to done |
156 | * RCU tasklet, tests passing through QSs, moves from current list to done list |
148 | */ |
157 | */ |
149 | void rcu_tasklet(void* data) |
158 | void rcu_tasklet(void* data) |
150 | { |
159 | { |
151 | rcu_callback_list_t* rd; |
160 | rcu_callback_list_t* rd; |
152 | bool passed_all_QS; |
161 | bool passed_all_QS; |
153 | #ifdef CONFIG_SMP |
162 | #ifdef CONFIG_SMP |
154 | int i; |
163 | int i; |
155 | #endif |
164 | #endif |
156 | ipl_t ipl; |
165 | ipl_t ipl; |
- | 166 | passed_all_QS = true; |
|
157 | 167 | ||
158 | ipl = interrupts_disable(); |
- | |
159 | 168 | ||
- | 169 | ipl = interrupts_disable(); |
|
160 | rcu_passQS(); |
170 | rcu_passQS(); |
161 | passed_all_QS = true; |
171 | |
162 | #ifdef CONFIG_SMP |
172 | #ifdef CONFIG_SMP |
163 | //check whether all CPUs have passed through QS |
173 | //check whether all CPUs have passed through QS of this CPU's current batch |
164 | for (i = 0; i < config.cpu_active; i++) |
174 | for (i = 0; i < config.cpu_count; i++) |
- | 175 | if (cpus[i].active) |
|
165 | passed_all_QS &= rcu_global[CPU->id].cpu_mask[i]; |
176 | passed_all_QS &= rcu_global[CPU->id].cpu_mask[i]; |
166 | #endif |
177 | #endif |
167 | if (passed_all_QS) { |
178 | if (passed_all_QS) { |
168 | //all CPUs have passed through QS -> grace period is over, we can schedule the call to RCU callback |
179 | //all CPUs have passed through QS -> grace period is over, we can schedule the call to RCU callback |
169 | if (rcu_global[CPU->id].done_batch) { |
180 | if (rcu_global[CPU->id].done_batch) { |
170 | rd = rcu_global[CPU->id].done_batch; |
181 | rd = rcu_global[CPU->id].done_batch; |
- | 182 | ||
171 | while (rd->next) rd = rd->next; |
183 | while (rd->next) rd = rd->next; |
172 | //append the current list to done list |
184 | //append the current list to done list |
173 | rd->next = rcu_global[CPU->id].current_batch; |
185 | rd->next = rcu_global[CPU->id].current_batch; |
174 | } else |
186 | } else |
175 | rcu_global[CPU->id].done_batch = rcu_global[CPU->id].current_batch; |
187 | rcu_global[CPU->id].done_batch = rcu_global[CPU->id].current_batch; |
176 | rcu_global[CPU->id].current_batch = NULL; |
188 | rcu_global[CPU->id].current_batch = NULL; |
177 | } |
189 | } |
178 | interrupts_restore(ipl); |
190 | interrupts_restore(ipl); |
179 | } |
191 | } |
180 | 192 | ||
181 | 193 | ||
182 | /** |
194 | /** |
183 | * This function indicates that the current CPU has gone through the quiescent state |
195 | * This function indicates that the current CPU has gone through the quiescent state |
184 | */ |
196 | */ |
185 | void rcu_passQS(void) |
197 | void rcu_passQS(void) |
186 | { |
198 | { |
187 | #ifdef CONFIG_SMP |
199 | #ifdef CONFIG_SMP |
188 | int i; |
200 | int i; |
189 | for (i=0;i<config.cpu_active;i++) |
201 | for (i = 0; i < config.cpu_count; i++) |
- | 202 | if (cpus[i].active) |
|
190 | //on all CPUs indicate that this CPU has gone through QS |
203 | //on all CPUs indicate that this CPU has gone through QS |
- | 204 | //this can overlap with clearing this flag in rcu_run_callbacks |
|
191 | rcu_global[i].cpu_mask[CPU->id]=true; |
205 | rcu_global[i].cpu_mask[CPU->id]=true; |
192 | #endif |
206 | #endif |
193 | } |
207 | } |
194 | 208 | ||
195 | 209 | ||
196 | /** |
210 | /** |
197 | * Moves RCUs from next to current, schedules RCU tasklet, calls the callbacks, frees the rcu_callback_list_t |
211 | * Moves RCU callbacks from next list to current list, schedules the RCU tasklet when needed, |
- | 212 | * calls the callbacks from done list, frees the rcu_callback_list_t |
|
198 | */ |
213 | */ |
199 | void rcu_run_callbacks(void) |
214 | void rcu_run_callbacks(void) |
200 | { |
215 | { |
201 | rcu_callback_list_t* rd, *rd2; |
216 | rcu_callback_list_t* rd, *rd2; |
202 | int i; |
217 | int i; |
203 | ipl_t ipl; |
218 | ipl_t ipl; |
204 | 219 | ||
205 | ipl = interrupts_disable(); |
220 | ipl = interrupts_disable(); |
206 | if (rcu_global[CPU->id].next_batch) { |
221 | if (rcu_global[CPU->id].next_batch) { |
207 | //we cannot append to the current list because callbacks from next batch |
222 | //we cannot append to the current list because the callbacks from next batch |
208 | //haven't passed the QSs |
223 | //haven't passed the QSs |
209 | if (rcu_global[CPU->id].current_batch == NULL) { |
224 | if (rcu_global[CPU->id].current_batch == NULL) { |
210 | rcu_global[CPU->id].current_batch = rcu_global[CPU->id].next_batch; |
225 | rcu_global[CPU->id].current_batch = rcu_global[CPU->id].next_batch; |
211 | rcu_global[CPU->id].next_batch = NULL; |
226 | rcu_global[CPU->id].next_batch = NULL; |
212 | #ifdef CONFIG_SMP |
227 | #ifdef CONFIG_SMP |
213 | //initialize our CPU mask |
228 | //initialize our CPU mask |
214 | for (i=0;i<config.cpu_active;i++) |
229 | for (i = 0; i < config.cpu_count; i++) |
- | 230 | if (cpus[i].active) |
|
215 | rcu_global[CPU->id].cpu_mask[i]=false; |
231 | rcu_global[CPU->id].cpu_mask[i]=false; |
216 | #endif |
232 | #endif |
217 | //schedule tasklet for all CPUs |
233 | //schedule tasklet for all CPUs |
218 | for (i=0;i<config.cpu_active;i++) { |
234 | for (i = 0; i < config.cpu_count; i++) |
- | 235 | if (cpus[i].active) |
|
219 | tasklet_schedule_SMP(rcu_tasklet_desc, i); |
236 | tasklet_schedule_SMP(rcu_tasklet_desc, i); |
220 | } |
- | |
221 | } |
237 | } |
222 | } |
238 | } |
223 | //this CPU has passed QS |
239 | //this CPU has passed QS |
224 | rcu_passQS(); |
240 | rcu_passQS(); |
225 | if (rcu_global[CPU->id].done_batch) { |
241 | if (rcu_global[CPU->id].done_batch) { |
226 | rd = rcu_global[CPU->id].done_batch; |
242 | rd = rcu_global[CPU->id].done_batch; |
227 | rcu_global[CPU->id].done_batch = NULL; |
243 | rcu_global[CPU->id].done_batch = NULL; |
- | 244 | //the callbacks (and free) can block, we must restore the interrupts |
|
228 | interrupts_restore(ipl); |
245 | interrupts_restore(ipl); |
229 | while (rd) { |
246 | while (rd) { |
230 | //call the callback |
247 | //call the callback |
- | 248 | if (rd->func == NULL) |
|
- | 249 | panic_printf("RCU callback function NULL, desc:%x", rd); |
|
231 | rd->func(rd->data); |
250 | rd->func(rd->data); |
232 | rd2 = rd->next; |
251 | rd2 = rd->next; |
233 | //free the structure |
252 | //free the structure |
234 | free(rd); |
253 | free(rd); |
235 | rd = rd2; |
254 | rd = rd2; |
236 | } |
255 | } |
237 | } |
256 | } |
238 | else |
257 | else |
239 | interrupts_restore(ipl); |
258 | interrupts_restore(ipl); |
240 | } |
259 | } |
241 | 260 | ||
242 | 261 | ||
243 | /** |
262 | /** |
244 | * Generic callback for RCU, frees @paramref pointer |
263 | * Generic callback for RCU, frees @paramref pointer |
245 | * @param pointer |
264 | * @param pointer |
246 | */ |
265 | */ |
247 | void rcu_callback_free(void* pointer) |
266 | void rcu_callback_free(void* pointer) |
248 | { |
267 | { |
249 | free(pointer); |
268 | free(pointer); |
250 | } |
269 | } |
251 | 270 | ||
252 | 271 |