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1 | /* test-fair-rwlock.c |
2 | * |
3 | */ |
4 | |
5 | #include <linux/module.h> |
6 | #include <linux/proc_fs.h> |
7 | #include <linux/sched.h> |
8 | #include <linux/timex.h> |
9 | #include <linux/fair-rwlock.h> |
10 | #include <linux/kthread.h> |
11 | #include <linux/delay.h> |
12 | #include <linux/hardirq.h> |
13 | #include <linux/module.h> |
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14 | #include <linux/percpu.h> |
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15 | #include <asm/ptrace.h> |
16 | |
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17 | #if (NR_CPUS > 64 && (BITS_PER_LONG == 32 || NR_CPUS > 32768)) |
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18 | #error "fair rwlock needs more bits per long to deal with that many CPUs" |
19 | #endif |
20 | |
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21 | /* Test duration, in seconds */ |
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22 | #define TEST_DURATION 60 |
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23 | |
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24 | #define THREAD_ROFFSET 1UL |
25 | #define THREAD_RMASK ((NR_CPUS - 1) * THREAD_ROFFSET) |
26 | #define SOFTIRQ_ROFFSET (THREAD_RMASK + 1) |
27 | #define SOFTIRQ_RMASK ((NR_CPUS - 1) * SOFTIRQ_ROFFSET) |
28 | #define HARDIRQ_ROFFSET ((SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
29 | #define HARDIRQ_RMASK ((NR_CPUS - 1) * HARDIRQ_ROFFSET) |
30 | |
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31 | #define SUBSCRIBERS_WOFFSET \ |
32 | ((HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
33 | #define SUBSCRIBERS_WMASK \ |
34 | ((NR_CPUS - 1) * SUBSCRIBERS_WOFFSET) |
35 | #define WRITER_MUTEX \ |
36 | ((SUBSCRIBERS_WMASK | HARDIRQ_RMASK | SOFTIRQ_RMASK | THREAD_RMASK) + 1) |
37 | #define SOFTIRQ_WMASK (WRITER_MUTEX << 1) |
38 | #define SOFTIRQ_WOFFSET SOFTIRQ_WMASK |
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39 | #define HARDIRQ_WMASK (SOFTIRQ_WMASK << 1) |
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40 | #define HARDIRQ_WOFFSET HARDIRQ_WMASK |
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41 | |
42 | #define NR_VARS 100 |
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43 | #define NR_WRITERS 2 |
44 | #define NR_TRYLOCK_WRITERS 2 |
45 | #define NR_READERS 4 |
46 | #define NR_TRYLOCK_READERS 2 |
47 | #define NR_INTERRUPT_READERS 1 |
48 | #define NR_TRYLOCK_INTERRUPT_READERS 1 |
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49 | |
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50 | /* |
51 | * Writer iteration delay, in us. 0 for busy loop. Caution : writers can |
52 | * starve readers. |
53 | */ |
54 | #define WRITER_DELAY 10 |
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55 | |
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56 | static int var[NR_VARS]; |
57 | static struct task_struct *reader_threads[NR_READERS]; |
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58 | static struct task_struct *trylock_reader_threads[NR_TRYLOCK_READERS]; |
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59 | static struct task_struct *writer_threads[NR_WRITERS]; |
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60 | static struct task_struct *trylock_writer_threads[NR_TRYLOCK_WRITERS]; |
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61 | static struct task_struct *interrupt_reader; |
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62 | static struct task_struct *trylock_interrupt_reader; |
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63 | |
64 | static struct fair_rwlock frwlock = { |
65 | .value = ATOMIC_LONG_INIT(0), |
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66 | }; |
67 | |
68 | struct proc_dir_entry *pentry = NULL; |
69 | |
70 | static int reader_thread(void *data) |
71 | { |
72 | int i; |
73 | int prev, cur; |
74 | unsigned long iter = 0; |
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75 | cycles_t time1, time2, delaymax = 0; |
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76 | |
77 | printk("reader_thread/%lu runnning\n", (unsigned long)data); |
78 | do { |
79 | iter++; |
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80 | preempt_disable(); /* for get_cycles accuracy */ |
81 | time1 = get_cycles(); |
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82 | fair_read_lock(&frwlock); |
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83 | time2 = get_cycles(); |
84 | delaymax = max(delaymax, time2 - time1); |
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85 | prev = var[0]; |
86 | for (i = 1; i < NR_VARS; i++) { |
87 | cur = var[i]; |
88 | if (cur != prev) |
89 | printk(KERN_ALERT |
90 | "Unequal cur %d/prev %d at i %d, iter %lu " |
91 | "in thread\n", cur, prev, i, iter); |
92 | } |
93 | fair_read_unlock(&frwlock); |
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94 | preempt_enable(); /* for get_cycles accuracy */ |
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95 | //msleep(100); |
96 | } while (!kthread_should_stop()); |
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97 | printk("reader_thread/%lu iterations : %lu, " |
98 | "max contention %llu cycles\n", |
99 | (unsigned long)data, iter, delaymax); |
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100 | return 0; |
101 | } |
102 | |
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103 | static int trylock_reader_thread(void *data) |
104 | { |
105 | int i; |
106 | int prev, cur; |
107 | unsigned long iter = 0, success_iter = 0; |
108 | |
109 | printk("trylock_reader_thread/%lu runnning\n", (unsigned long)data); |
110 | do { |
111 | while (!fair_read_trylock(&frwlock)) |
112 | iter++; |
113 | success_iter++; |
114 | prev = var[0]; |
115 | for (i = 1; i < NR_VARS; i++) { |
116 | cur = var[i]; |
117 | if (cur != prev) |
118 | printk(KERN_ALERT |
119 | "Unequal cur %d/prev %d at i %d, iter %lu " |
120 | "in thread\n", cur, prev, i, iter); |
121 | } |
122 | fair_read_unlock(&frwlock); |
123 | //msleep(100); |
124 | } while (!kthread_should_stop()); |
125 | printk("trylock_reader_thread/%lu iterations : %lu, " |
126 | "successful iterations : %lu\n", |
127 | (unsigned long)data, iter, success_iter); |
128 | return 0; |
129 | } |
130 | |
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131 | DEFINE_PER_CPU(cycles_t, int_delaymax); |
132 | |
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133 | static void interrupt_reader_ipi(void *data) |
134 | { |
135 | int i; |
136 | int prev, cur; |
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137 | cycles_t time1, time2; |
138 | cycles_t *delaymax; |
139 | |
140 | /* |
141 | * Skip the ipi caller, not in irq context. |
142 | */ |
143 | if (!in_irq()) |
144 | return; |
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145 | |
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146 | delaymax = &per_cpu(int_delaymax, smp_processor_id()); |
147 | time1 = get_cycles(); |
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148 | fair_read_lock(&frwlock); |
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149 | time2 = get_cycles(); |
150 | *delaymax = max(*delaymax, time2 - time1); |
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151 | prev = var[0]; |
152 | for (i = 1; i < NR_VARS; i++) { |
153 | cur = var[i]; |
154 | if (cur != prev) |
155 | printk(KERN_ALERT |
156 | "Unequal cur %d/prev %d at i %d in interrupt\n", |
157 | cur, prev, i); |
158 | } |
159 | fair_read_unlock(&frwlock); |
160 | } |
161 | |
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162 | DEFINE_PER_CPU(unsigned long, trylock_int_iter); |
163 | DEFINE_PER_CPU(unsigned long, trylock_int_success); |
164 | |
165 | static void trylock_interrupt_reader_ipi(void *data) |
166 | { |
167 | int i; |
168 | int prev, cur; |
169 | |
170 | /* |
171 | * Skip the ipi caller, not in irq context. |
172 | */ |
173 | if (!in_irq()) |
174 | return; |
175 | |
176 | per_cpu(trylock_int_iter, smp_processor_id())++; |
177 | while (!fair_read_trylock(&frwlock)) |
178 | per_cpu(trylock_int_iter, smp_processor_id())++; |
179 | per_cpu(trylock_int_success, smp_processor_id())++; |
180 | prev = var[0]; |
181 | for (i = 1; i < NR_VARS; i++) { |
182 | cur = var[i]; |
183 | if (cur != prev) |
184 | printk(KERN_ALERT |
185 | "Unequal cur %d/prev %d at i %d in interrupt\n", |
186 | cur, prev, i); |
187 | } |
188 | fair_read_unlock(&frwlock); |
189 | } |
190 | |
191 | |
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192 | static int interrupt_reader_thread(void *data) |
193 | { |
194 | unsigned long iter = 0; |
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195 | int i; |
196 | |
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197 | do { |
198 | iter++; |
199 | on_each_cpu(interrupt_reader_ipi, NULL, 0); |
200 | msleep(100); |
201 | } while (!kthread_should_stop()); |
202 | printk("interrupt_reader_thread/%lu iterations : %lu\n", |
203 | (unsigned long)data, iter); |
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204 | for_each_online_cpu(i) { |
205 | printk("interrupt readers on CPU %i, " |
206 | "max contention : %llu cycles\n", |
207 | i, per_cpu(int_delaymax, i)); |
208 | } |
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209 | return 0; |
210 | } |
211 | |
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212 | static int trylock_interrupt_reader_thread(void *data) |
213 | { |
214 | unsigned long iter = 0; |
215 | int i; |
216 | |
217 | do { |
218 | iter++; |
219 | on_each_cpu(trylock_interrupt_reader_ipi, NULL, 0); |
220 | msleep(100); |
221 | } while (!kthread_should_stop()); |
222 | printk("trylock_interrupt_reader_thread/%lu iterations : %lu\n", |
223 | (unsigned long)data, iter); |
224 | for_each_online_cpu(i) { |
225 | printk("trylock interrupt readers on CPU %i, " |
226 | "iterations %lu, " |
227 | "successful iterations : %lu\n", |
228 | i, per_cpu(trylock_int_iter, i), |
229 | per_cpu(trylock_int_success, i)); |
230 | } |
231 | return 0; |
232 | } |
233 | |
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234 | static int writer_thread(void *data) |
235 | { |
236 | int i; |
237 | int new; |
238 | unsigned long iter = 0; |
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239 | cycles_t time1, time2, delaymax = 0; |
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240 | |
241 | printk("writer_thread/%lu runnning\n", (unsigned long)data); |
242 | do { |
243 | iter++; |
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244 | preempt_disable(); /* for get_cycles accuracy */ |
245 | time1 = get_cycles(); |
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246 | fair_write_lock_irq(&frwlock); |
247 | //fair_write_lock(&frwlock); |
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248 | time2 = get_cycles(); |
249 | delaymax = max(delaymax, time2 - time1); |
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250 | new = (int)get_cycles(); |
251 | for (i = 0; i < NR_VARS; i++) { |
252 | var[i] = new; |
253 | } |
254 | //fair_write_unlock(&frwlock); |
255 | fair_write_unlock_irq(&frwlock); |
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256 | preempt_enable(); /* for get_cycles accuracy */ |
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257 | if (WRITER_DELAY > 0) |
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258 | udelay(WRITER_DELAY); |
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259 | } while (!kthread_should_stop()); |
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260 | printk("writer_thread/%lu iterations : %lu, " |
261 | "max contention %llu cycles\n", |
262 | (unsigned long)data, iter, delaymax); |
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263 | return 0; |
264 | } |
265 | |
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266 | static int trylock_writer_thread(void *data) |
267 | { |
268 | int i; |
269 | int new; |
270 | unsigned long iter = 0, success = 0; |
271 | |
272 | printk("trylock_writer_thread/%lu runnning\n", (unsigned long)data); |
273 | do { |
274 | fair_write_subscribe(&frwlock); |
275 | while (!fair_write_trylock_subscribed_irq(&frwlock)) { |
276 | iter++; |
277 | continue; |
278 | } |
279 | success++; |
280 | //fair_write_lock(&frwlock); |
281 | new = (int)get_cycles(); |
282 | for (i = 0; i < NR_VARS; i++) { |
283 | var[i] = new; |
284 | } |
285 | //fair_write_unlock(&frwlock); |
286 | fair_write_unlock_irq(&frwlock); |
287 | if (WRITER_DELAY > 0) |
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288 | udelay(WRITER_DELAY); |
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289 | } while (!kthread_should_stop()); |
290 | printk("trylock_writer_thread/%lu iterations : %lu, " |
291 | "successful iterations : %lu\n", |
292 | (unsigned long)data, iter, success); |
293 | return 0; |
294 | } |
295 | |
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296 | static void fair_rwlock_create(void) |
297 | { |
298 | unsigned long i; |
299 | |
300 | for (i = 0; i < NR_READERS; i++) { |
301 | printk("starting reader thread %lu\n", i); |
302 | reader_threads[i] = kthread_run(reader_thread, (void *)i, |
303 | "frwlock_reader"); |
304 | BUG_ON(!reader_threads[i]); |
305 | } |
306 | |
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307 | for (i = 0; i < NR_TRYLOCK_READERS; i++) { |
308 | printk("starting trylock reader thread %lu\n", i); |
309 | trylock_reader_threads[i] = kthread_run(trylock_reader_thread, |
310 | (void *)i, "frwlock_trylock_reader"); |
311 | BUG_ON(!trylock_reader_threads[i]); |
312 | } |
313 | |
314 | |
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315 | printk("starting interrupt reader %lu\n", i); |
316 | interrupt_reader = kthread_run(interrupt_reader_thread, NULL, |
317 | "frwlock_interrupt_reader"); |
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318 | printk("starting trylock interrupt reader %lu\n", i); |
319 | trylock_interrupt_reader = kthread_run(trylock_interrupt_reader_thread, |
320 | NULL, "frwlock_trylock_interrupt_reader"); |
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321 | |
322 | for (i = 0; i < NR_WRITERS; i++) { |
323 | printk("starting writer thread %lu\n", i); |
324 | writer_threads[i] = kthread_run(writer_thread, (void *)i, |
325 | "frwlock_writer"); |
326 | BUG_ON(!writer_threads[i]); |
327 | } |
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328 | for (i = 0; i < NR_TRYLOCK_WRITERS; i++) { |
329 | printk("starting trylock writer thread %lu\n", i); |
330 | trylock_writer_threads[i] = kthread_run(trylock_writer_thread, |
331 | (void *)i, "frwlock_trylock_writer"); |
332 | BUG_ON(!trylock_writer_threads[i]); |
333 | } |
334 | |
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335 | } |
336 | |
337 | static void fair_rwlock_stop(void) |
338 | { |
339 | unsigned long i; |
340 | |
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341 | for (i = 0; i < NR_WRITERS; i++) |
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342 | kthread_stop(writer_threads[i]); |
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343 | for (i = 0; i < NR_TRYLOCK_WRITERS; i++) |
344 | kthread_stop(trylock_writer_threads[i]); |
345 | for (i = 0; i < NR_READERS; i++) |
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346 | kthread_stop(reader_threads[i]); |
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347 | for (i = 0; i < NR_TRYLOCK_READERS; i++) |
348 | kthread_stop(trylock_reader_threads[i]); |
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349 | kthread_stop(interrupt_reader); |
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350 | kthread_stop(trylock_interrupt_reader); |
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351 | } |
352 | |
353 | |
354 | static void perform_test(const char *name, void (*callback)(void)) |
355 | { |
356 | printk("%s\n", name); |
357 | callback(); |
358 | } |
359 | |
360 | static int my_open(struct inode *inode, struct file *file) |
361 | { |
362 | perform_test("fair-rwlock-create", fair_rwlock_create); |
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363 | ssleep(TEST_DURATION); |
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364 | perform_test("fair-rwlock-stop", fair_rwlock_stop); |
365 | |
366 | return -EPERM; |
367 | } |
368 | |
369 | |
370 | static struct file_operations my_operations = { |
371 | .open = my_open, |
372 | }; |
373 | |
374 | int init_module(void) |
375 | { |
376 | pentry = create_proc_entry("testfrwlock", 0444, NULL); |
377 | if (pentry) |
378 | pentry->proc_fops = &my_operations; |
379 | |
380 | printk("NR_CPUS : %d\n", NR_CPUS); |
381 | printk("THREAD_ROFFSET : %lX\n", THREAD_ROFFSET); |
382 | printk("THREAD_RMASK : %lX\n", THREAD_RMASK); |
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383 | printk("SOFTIRQ_ROFFSET : %lX\n", SOFTIRQ_ROFFSET); |
384 | printk("SOFTIRQ_RMASK : %lX\n", SOFTIRQ_RMASK); |
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385 | printk("HARDIRQ_ROFFSET : %lX\n", HARDIRQ_ROFFSET); |
386 | printk("HARDIRQ_RMASK : %lX\n", HARDIRQ_RMASK); |
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387 | printk("SUBSCRIBERS_WOFFSET : %lX\n", SUBSCRIBERS_WOFFSET); |
388 | printk("SUBSCRIBERS_WMASK : %lX\n", SUBSCRIBERS_WMASK); |
389 | printk("WRITER_MUTEX : %lX\n", WRITER_MUTEX); |
390 | printk("SOFTIRQ_WMASK : %lX\n", SOFTIRQ_WMASK); |
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391 | printk("HARDIRQ_WMASK : %lX\n", HARDIRQ_WMASK); |
392 | |
393 | return 0; |
394 | } |
395 | |
396 | void cleanup_module(void) |
397 | { |
398 | remove_proc_entry("testfrwlock", NULL); |
399 | } |
400 | |
401 | MODULE_LICENSE("GPL"); |
402 | MODULE_AUTHOR("Mathieu Desnoyers"); |
403 | MODULE_DESCRIPTION("Fair rwlock test"); |