Root/kernel/rtmutex-tester.c

1/*
2 * RT-Mutex-tester: scriptable tester for rt mutexes
3 *
4 * started by Thomas Gleixner:
5 *
6 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
7 *
8 */
9#include <linux/device.h>
10#include <linux/kthread.h>
11#include <linux/export.h>
12#include <linux/sched.h>
13#include <linux/spinlock.h>
14#include <linux/timer.h>
15#include <linux/freezer.h>
16
17#include "rtmutex.h"
18
19#define MAX_RT_TEST_THREADS 8
20#define MAX_RT_TEST_MUTEXES 8
21
22static spinlock_t rttest_lock;
23static atomic_t rttest_event;
24
25struct test_thread_data {
26    int opcode;
27    int opdata;
28    int mutexes[MAX_RT_TEST_MUTEXES];
29    int event;
30    struct device dev;
31};
32
33static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
34static struct task_struct *threads[MAX_RT_TEST_THREADS];
35static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
36
37enum test_opcodes {
38    RTTEST_NOP = 0,
39    RTTEST_SCHEDOT, /* 1 Sched other, data = nice */
40    RTTEST_SCHEDRT, /* 2 Sched fifo, data = prio */
41    RTTEST_LOCK, /* 3 Lock uninterruptible, data = lockindex */
42    RTTEST_LOCKNOWAIT, /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
43    RTTEST_LOCKINT, /* 5 Lock interruptible, data = lockindex */
44    RTTEST_LOCKINTNOWAIT, /* 6 Lock interruptible no wait in wakeup, data = lockindex */
45    RTTEST_LOCKCONT, /* 7 Continue locking after the wakeup delay */
46    RTTEST_UNLOCK, /* 8 Unlock, data = lockindex */
47    /* 9, 10 - reserved for BKL commemoration */
48    RTTEST_SIGNAL = 11, /* 11 Signal other test thread, data = thread id */
49    RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
50    RTTEST_RESET = 99, /* 99 Reset all pending operations */
51};
52
53static int handle_op(struct test_thread_data *td, int lockwakeup)
54{
55    int i, id, ret = -EINVAL;
56
57    switch(td->opcode) {
58
59    case RTTEST_NOP:
60        return 0;
61
62    case RTTEST_LOCKCONT:
63        td->mutexes[td->opdata] = 1;
64        td->event = atomic_add_return(1, &rttest_event);
65        return 0;
66
67    case RTTEST_RESET:
68        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
69            if (td->mutexes[i] == 4) {
70                rt_mutex_unlock(&mutexes[i]);
71                td->mutexes[i] = 0;
72            }
73        }
74        return 0;
75
76    case RTTEST_RESETEVENT:
77        atomic_set(&rttest_event, 0);
78        return 0;
79
80    default:
81        if (lockwakeup)
82            return ret;
83    }
84
85    switch(td->opcode) {
86
87    case RTTEST_LOCK:
88    case RTTEST_LOCKNOWAIT:
89        id = td->opdata;
90        if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
91            return ret;
92
93        td->mutexes[id] = 1;
94        td->event = atomic_add_return(1, &rttest_event);
95        rt_mutex_lock(&mutexes[id]);
96        td->event = atomic_add_return(1, &rttest_event);
97        td->mutexes[id] = 4;
98        return 0;
99
100    case RTTEST_LOCKINT:
101    case RTTEST_LOCKINTNOWAIT:
102        id = td->opdata;
103        if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
104            return ret;
105
106        td->mutexes[id] = 1;
107        td->event = atomic_add_return(1, &rttest_event);
108        ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
109        td->event = atomic_add_return(1, &rttest_event);
110        td->mutexes[id] = ret ? 0 : 4;
111        return ret ? -EINTR : 0;
112
113    case RTTEST_UNLOCK:
114        id = td->opdata;
115        if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
116            return ret;
117
118        td->event = atomic_add_return(1, &rttest_event);
119        rt_mutex_unlock(&mutexes[id]);
120        td->event = atomic_add_return(1, &rttest_event);
121        td->mutexes[id] = 0;
122        return 0;
123
124    default:
125        break;
126    }
127    return ret;
128}
129
130/*
131 * Schedule replacement for rtsem_down(). Only called for threads with
132 * PF_MUTEX_TESTER set.
133 *
134 * This allows us to have finegrained control over the event flow.
135 *
136 */
137void schedule_rt_mutex_test(struct rt_mutex *mutex)
138{
139    int tid, op, dat;
140    struct test_thread_data *td;
141
142    /* We have to lookup the task */
143    for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
144        if (threads[tid] == current)
145            break;
146    }
147
148    BUG_ON(tid == MAX_RT_TEST_THREADS);
149
150    td = &thread_data[tid];
151
152    op = td->opcode;
153    dat = td->opdata;
154
155    switch (op) {
156    case RTTEST_LOCK:
157    case RTTEST_LOCKINT:
158    case RTTEST_LOCKNOWAIT:
159    case RTTEST_LOCKINTNOWAIT:
160        if (mutex != &mutexes[dat])
161            break;
162
163        if (td->mutexes[dat] != 1)
164            break;
165
166        td->mutexes[dat] = 2;
167        td->event = atomic_add_return(1, &rttest_event);
168        break;
169
170    default:
171        break;
172    }
173
174    schedule();
175
176
177    switch (op) {
178    case RTTEST_LOCK:
179    case RTTEST_LOCKINT:
180        if (mutex != &mutexes[dat])
181            return;
182
183        if (td->mutexes[dat] != 2)
184            return;
185
186        td->mutexes[dat] = 3;
187        td->event = atomic_add_return(1, &rttest_event);
188        break;
189
190    case RTTEST_LOCKNOWAIT:
191    case RTTEST_LOCKINTNOWAIT:
192        if (mutex != &mutexes[dat])
193            return;
194
195        if (td->mutexes[dat] != 2)
196            return;
197
198        td->mutexes[dat] = 1;
199        td->event = atomic_add_return(1, &rttest_event);
200        return;
201
202    default:
203        return;
204    }
205
206    td->opcode = 0;
207
208    for (;;) {
209        set_current_state(TASK_INTERRUPTIBLE);
210
211        if (td->opcode > 0) {
212            int ret;
213
214            set_current_state(TASK_RUNNING);
215            ret = handle_op(td, 1);
216            set_current_state(TASK_INTERRUPTIBLE);
217            if (td->opcode == RTTEST_LOCKCONT)
218                break;
219            td->opcode = ret;
220        }
221
222        /* Wait for the next command to be executed */
223        schedule();
224    }
225
226    /* Restore previous command and data */
227    td->opcode = op;
228    td->opdata = dat;
229}
230
231static int test_func(void *data)
232{
233    struct test_thread_data *td = data;
234    int ret;
235
236    current->flags |= PF_MUTEX_TESTER;
237    set_freezable();
238    allow_signal(SIGHUP);
239
240    for(;;) {
241
242        set_current_state(TASK_INTERRUPTIBLE);
243
244        if (td->opcode > 0) {
245            set_current_state(TASK_RUNNING);
246            ret = handle_op(td, 0);
247            set_current_state(TASK_INTERRUPTIBLE);
248            td->opcode = ret;
249        }
250
251        /* Wait for the next command to be executed */
252        schedule();
253        try_to_freeze();
254
255        if (signal_pending(current))
256            flush_signals(current);
257
258        if(kthread_should_stop())
259            break;
260    }
261    return 0;
262}
263
264/**
265 * sysfs_test_command - interface for test commands
266 * @dev: thread reference
267 * @buf: command for actual step
268 * @count: length of buffer
269 *
270 * command syntax:
271 *
272 * opcode:data
273 */
274static ssize_t sysfs_test_command(struct device *dev, struct device_attribute *attr,
275                  const char *buf, size_t count)
276{
277    struct sched_param schedpar;
278    struct test_thread_data *td;
279    char cmdbuf[32];
280    int op, dat, tid, ret;
281
282    td = container_of(dev, struct test_thread_data, dev);
283    tid = td->dev.id;
284
285    /* strings from sysfs write are not 0 terminated! */
286    if (count >= sizeof(cmdbuf))
287        return -EINVAL;
288
289    /* strip of \n: */
290    if (buf[count-1] == '\n')
291        count--;
292    if (count < 1)
293        return -EINVAL;
294
295    memcpy(cmdbuf, buf, count);
296    cmdbuf[count] = 0;
297
298    if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
299        return -EINVAL;
300
301    switch (op) {
302    case RTTEST_SCHEDOT:
303        schedpar.sched_priority = 0;
304        ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
305        if (ret)
306            return ret;
307        set_user_nice(current, 0);
308        break;
309
310    case RTTEST_SCHEDRT:
311        schedpar.sched_priority = dat;
312        ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
313        if (ret)
314            return ret;
315        break;
316
317    case RTTEST_SIGNAL:
318        send_sig(SIGHUP, threads[tid], 0);
319        break;
320
321    default:
322        if (td->opcode > 0)
323            return -EBUSY;
324        td->opdata = dat;
325        td->opcode = op;
326        wake_up_process(threads[tid]);
327    }
328
329    return count;
330}
331
332/**
333 * sysfs_test_status - sysfs interface for rt tester
334 * @dev: thread to query
335 * @buf: char buffer to be filled with thread status info
336 */
337static ssize_t sysfs_test_status(struct device *dev, struct device_attribute *attr,
338                 char *buf)
339{
340    struct test_thread_data *td;
341    struct task_struct *tsk;
342    char *curr = buf;
343    int i;
344
345    td = container_of(dev, struct test_thread_data, dev);
346    tsk = threads[td->dev.id];
347
348    spin_lock(&rttest_lock);
349
350    curr += sprintf(curr,
351        "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, M:",
352        td->opcode, td->event, tsk->state,
353            (MAX_RT_PRIO - 1) - tsk->prio,
354            (MAX_RT_PRIO - 1) - tsk->normal_prio,
355        tsk->pi_blocked_on);
356
357    for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
358        curr += sprintf(curr, "%d", td->mutexes[i]);
359
360    spin_unlock(&rttest_lock);
361
362    curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
363            mutexes[td->dev.id].owner);
364
365    return curr - buf;
366}
367
368static DEVICE_ATTR(status, 0600, sysfs_test_status, NULL);
369static DEVICE_ATTR(command, 0600, NULL, sysfs_test_command);
370
371static struct bus_type rttest_subsys = {
372    .name = "rttest",
373    .dev_name = "rttest",
374};
375
376static int init_test_thread(int id)
377{
378    thread_data[id].dev.bus = &rttest_subsys;
379    thread_data[id].dev.id = id;
380
381    threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
382    if (IS_ERR(threads[id]))
383        return PTR_ERR(threads[id]);
384
385    return device_register(&thread_data[id].dev);
386}
387
388static int init_rttest(void)
389{
390    int ret, i;
391
392    spin_lock_init(&rttest_lock);
393
394    for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
395        rt_mutex_init(&mutexes[i]);
396
397    ret = subsys_system_register(&rttest_subsys, NULL);
398    if (ret)
399        return ret;
400
401    for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
402        ret = init_test_thread(i);
403        if (ret)
404            break;
405        ret = device_create_file(&thread_data[i].dev, &dev_attr_status);
406        if (ret)
407            break;
408        ret = device_create_file(&thread_data[i].dev, &dev_attr_command);
409        if (ret)
410            break;
411    }
412
413    printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
414
415    return ret;
416}
417
418device_initcall(init_rttest);
419

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