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/kthread.h>
10#include <linux/module.h>
11#include <linux/sched.h>
12#include <linux/smp_lock.h>
13#include <linux/spinlock.h>
14#include <linux/sysdev.h>
15#include <linux/timer.h>
16#include <linux/freezer.h>
17
18#include "rtmutex.h"
19
20#define MAX_RT_TEST_THREADS 8
21#define MAX_RT_TEST_MUTEXES 8
22
23static spinlock_t rttest_lock;
24static atomic_t rttest_event;
25
26struct test_thread_data {
27    int opcode;
28    int opdata;
29    int mutexes[MAX_RT_TEST_MUTEXES];
30    int bkl;
31    int event;
32    struct sys_device sysdev;
33};
34
35static struct test_thread_data thread_data[MAX_RT_TEST_THREADS];
36static struct task_struct *threads[MAX_RT_TEST_THREADS];
37static struct rt_mutex mutexes[MAX_RT_TEST_MUTEXES];
38
39enum test_opcodes {
40    RTTEST_NOP = 0,
41    RTTEST_SCHEDOT, /* 1 Sched other, data = nice */
42    RTTEST_SCHEDRT, /* 2 Sched fifo, data = prio */
43    RTTEST_LOCK, /* 3 Lock uninterruptible, data = lockindex */
44    RTTEST_LOCKNOWAIT, /* 4 Lock uninterruptible no wait in wakeup, data = lockindex */
45    RTTEST_LOCKINT, /* 5 Lock interruptible, data = lockindex */
46    RTTEST_LOCKINTNOWAIT, /* 6 Lock interruptible no wait in wakeup, data = lockindex */
47    RTTEST_LOCKCONT, /* 7 Continue locking after the wakeup delay */
48    RTTEST_UNLOCK, /* 8 Unlock, data = lockindex */
49    RTTEST_LOCKBKL, /* 9 Lock BKL */
50    RTTEST_UNLOCKBKL, /* 10 Unlock BKL */
51    RTTEST_SIGNAL, /* 11 Signal other test thread, data = thread id */
52    RTTEST_RESETEVENT = 98, /* 98 Reset event counter */
53    RTTEST_RESET = 99, /* 99 Reset all pending operations */
54};
55
56static int handle_op(struct test_thread_data *td, int lockwakeup)
57{
58    int i, id, ret = -EINVAL;
59
60    switch(td->opcode) {
61
62    case RTTEST_NOP:
63        return 0;
64
65    case RTTEST_LOCKCONT:
66        td->mutexes[td->opdata] = 1;
67        td->event = atomic_add_return(1, &rttest_event);
68        return 0;
69
70    case RTTEST_RESET:
71        for (i = 0; i < MAX_RT_TEST_MUTEXES; i++) {
72            if (td->mutexes[i] == 4) {
73                rt_mutex_unlock(&mutexes[i]);
74                td->mutexes[i] = 0;
75            }
76        }
77
78        if (!lockwakeup && td->bkl == 4) {
79#ifdef CONFIG_LOCK_KERNEL
80            unlock_kernel();
81#endif
82            td->bkl = 0;
83        }
84        return 0;
85
86    case RTTEST_RESETEVENT:
87        atomic_set(&rttest_event, 0);
88        return 0;
89
90    default:
91        if (lockwakeup)
92            return ret;
93    }
94
95    switch(td->opcode) {
96
97    case RTTEST_LOCK:
98    case RTTEST_LOCKNOWAIT:
99        id = td->opdata;
100        if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
101            return ret;
102
103        td->mutexes[id] = 1;
104        td->event = atomic_add_return(1, &rttest_event);
105        rt_mutex_lock(&mutexes[id]);
106        td->event = atomic_add_return(1, &rttest_event);
107        td->mutexes[id] = 4;
108        return 0;
109
110    case RTTEST_LOCKINT:
111    case RTTEST_LOCKINTNOWAIT:
112        id = td->opdata;
113        if (id < 0 || id >= MAX_RT_TEST_MUTEXES)
114            return ret;
115
116        td->mutexes[id] = 1;
117        td->event = atomic_add_return(1, &rttest_event);
118        ret = rt_mutex_lock_interruptible(&mutexes[id], 0);
119        td->event = atomic_add_return(1, &rttest_event);
120        td->mutexes[id] = ret ? 0 : 4;
121        return ret ? -EINTR : 0;
122
123    case RTTEST_UNLOCK:
124        id = td->opdata;
125        if (id < 0 || id >= MAX_RT_TEST_MUTEXES || td->mutexes[id] != 4)
126            return ret;
127
128        td->event = atomic_add_return(1, &rttest_event);
129        rt_mutex_unlock(&mutexes[id]);
130        td->event = atomic_add_return(1, &rttest_event);
131        td->mutexes[id] = 0;
132        return 0;
133
134    case RTTEST_LOCKBKL:
135        if (td->bkl)
136            return 0;
137        td->bkl = 1;
138#ifdef CONFIG_LOCK_KERNEL
139        lock_kernel();
140#endif
141        td->bkl = 4;
142        return 0;
143
144    case RTTEST_UNLOCKBKL:
145        if (td->bkl != 4)
146            break;
147#ifdef CONFIG_LOCK_KERNEL
148        unlock_kernel();
149#endif
150        td->bkl = 0;
151        return 0;
152
153    default:
154        break;
155    }
156    return ret;
157}
158
159/*
160 * Schedule replacement for rtsem_down(). Only called for threads with
161 * PF_MUTEX_TESTER set.
162 *
163 * This allows us to have finegrained control over the event flow.
164 *
165 */
166void schedule_rt_mutex_test(struct rt_mutex *mutex)
167{
168    int tid, op, dat;
169    struct test_thread_data *td;
170
171    /* We have to lookup the task */
172    for (tid = 0; tid < MAX_RT_TEST_THREADS; tid++) {
173        if (threads[tid] == current)
174            break;
175    }
176
177    BUG_ON(tid == MAX_RT_TEST_THREADS);
178
179    td = &thread_data[tid];
180
181    op = td->opcode;
182    dat = td->opdata;
183
184    switch (op) {
185    case RTTEST_LOCK:
186    case RTTEST_LOCKINT:
187    case RTTEST_LOCKNOWAIT:
188    case RTTEST_LOCKINTNOWAIT:
189        if (mutex != &mutexes[dat])
190            break;
191
192        if (td->mutexes[dat] != 1)
193            break;
194
195        td->mutexes[dat] = 2;
196        td->event = atomic_add_return(1, &rttest_event);
197        break;
198
199    case RTTEST_LOCKBKL:
200    default:
201        break;
202    }
203
204    schedule();
205
206
207    switch (op) {
208    case RTTEST_LOCK:
209    case RTTEST_LOCKINT:
210        if (mutex != &mutexes[dat])
211            return;
212
213        if (td->mutexes[dat] != 2)
214            return;
215
216        td->mutexes[dat] = 3;
217        td->event = atomic_add_return(1, &rttest_event);
218        break;
219
220    case RTTEST_LOCKNOWAIT:
221    case RTTEST_LOCKINTNOWAIT:
222        if (mutex != &mutexes[dat])
223            return;
224
225        if (td->mutexes[dat] != 2)
226            return;
227
228        td->mutexes[dat] = 1;
229        td->event = atomic_add_return(1, &rttest_event);
230        return;
231
232    case RTTEST_LOCKBKL:
233        return;
234    default:
235        return;
236    }
237
238    td->opcode = 0;
239
240    for (;;) {
241        set_current_state(TASK_INTERRUPTIBLE);
242
243        if (td->opcode > 0) {
244            int ret;
245
246            set_current_state(TASK_RUNNING);
247            ret = handle_op(td, 1);
248            set_current_state(TASK_INTERRUPTIBLE);
249            if (td->opcode == RTTEST_LOCKCONT)
250                break;
251            td->opcode = ret;
252        }
253
254        /* Wait for the next command to be executed */
255        schedule();
256    }
257
258    /* Restore previous command and data */
259    td->opcode = op;
260    td->opdata = dat;
261}
262
263static int test_func(void *data)
264{
265    struct test_thread_data *td = data;
266    int ret;
267
268    current->flags |= PF_MUTEX_TESTER;
269    set_freezable();
270    allow_signal(SIGHUP);
271
272    for(;;) {
273
274        set_current_state(TASK_INTERRUPTIBLE);
275
276        if (td->opcode > 0) {
277            set_current_state(TASK_RUNNING);
278            ret = handle_op(td, 0);
279            set_current_state(TASK_INTERRUPTIBLE);
280            td->opcode = ret;
281        }
282
283        /* Wait for the next command to be executed */
284        schedule();
285        try_to_freeze();
286
287        if (signal_pending(current))
288            flush_signals(current);
289
290        if(kthread_should_stop())
291            break;
292    }
293    return 0;
294}
295
296/**
297 * sysfs_test_command - interface for test commands
298 * @dev: thread reference
299 * @buf: command for actual step
300 * @count: length of buffer
301 *
302 * command syntax:
303 *
304 * opcode:data
305 */
306static ssize_t sysfs_test_command(struct sys_device *dev, struct sysdev_attribute *attr,
307                  const char *buf, size_t count)
308{
309    struct sched_param schedpar;
310    struct test_thread_data *td;
311    char cmdbuf[32];
312    int op, dat, tid, ret;
313
314    td = container_of(dev, struct test_thread_data, sysdev);
315    tid = td->sysdev.id;
316
317    /* strings from sysfs write are not 0 terminated! */
318    if (count >= sizeof(cmdbuf))
319        return -EINVAL;
320
321    /* strip of \n: */
322    if (buf[count-1] == '\n')
323        count--;
324    if (count < 1)
325        return -EINVAL;
326
327    memcpy(cmdbuf, buf, count);
328    cmdbuf[count] = 0;
329
330    if (sscanf(cmdbuf, "%d:%d", &op, &dat) != 2)
331        return -EINVAL;
332
333    switch (op) {
334    case RTTEST_SCHEDOT:
335        schedpar.sched_priority = 0;
336        ret = sched_setscheduler(threads[tid], SCHED_NORMAL, &schedpar);
337        if (ret)
338            return ret;
339        set_user_nice(current, 0);
340        break;
341
342    case RTTEST_SCHEDRT:
343        schedpar.sched_priority = dat;
344        ret = sched_setscheduler(threads[tid], SCHED_FIFO, &schedpar);
345        if (ret)
346            return ret;
347        break;
348
349    case RTTEST_SIGNAL:
350        send_sig(SIGHUP, threads[tid], 0);
351        break;
352
353    default:
354        if (td->opcode > 0)
355            return -EBUSY;
356        td->opdata = dat;
357        td->opcode = op;
358        wake_up_process(threads[tid]);
359    }
360
361    return count;
362}
363
364/**
365 * sysfs_test_status - sysfs interface for rt tester
366 * @dev: thread to query
367 * @buf: char buffer to be filled with thread status info
368 */
369static ssize_t sysfs_test_status(struct sys_device *dev, struct sysdev_attribute *attr,
370                 char *buf)
371{
372    struct test_thread_data *td;
373    struct task_struct *tsk;
374    char *curr = buf;
375    int i;
376
377    td = container_of(dev, struct test_thread_data, sysdev);
378    tsk = threads[td->sysdev.id];
379
380    spin_lock(&rttest_lock);
381
382    curr += sprintf(curr,
383        "O: %4d, E:%8d, S: 0x%08lx, P: %4d, N: %4d, B: %p, K: %d, M:",
384        td->opcode, td->event, tsk->state,
385            (MAX_RT_PRIO - 1) - tsk->prio,
386            (MAX_RT_PRIO - 1) - tsk->normal_prio,
387        tsk->pi_blocked_on, td->bkl);
388
389    for (i = MAX_RT_TEST_MUTEXES - 1; i >=0 ; i--)
390        curr += sprintf(curr, "%d", td->mutexes[i]);
391
392    spin_unlock(&rttest_lock);
393
394    curr += sprintf(curr, ", T: %p, R: %p\n", tsk,
395            mutexes[td->sysdev.id].owner);
396
397    return curr - buf;
398}
399
400static SYSDEV_ATTR(status, 0600, sysfs_test_status, NULL);
401static SYSDEV_ATTR(command, 0600, NULL, sysfs_test_command);
402
403static struct sysdev_class rttest_sysclass = {
404    .name = "rttest",
405};
406
407static int init_test_thread(int id)
408{
409    thread_data[id].sysdev.cls = &rttest_sysclass;
410    thread_data[id].sysdev.id = id;
411
412    threads[id] = kthread_run(test_func, &thread_data[id], "rt-test-%d", id);
413    if (IS_ERR(threads[id]))
414        return PTR_ERR(threads[id]);
415
416    return sysdev_register(&thread_data[id].sysdev);
417}
418
419static int init_rttest(void)
420{
421    int ret, i;
422
423    spin_lock_init(&rttest_lock);
424
425    for (i = 0; i < MAX_RT_TEST_MUTEXES; i++)
426        rt_mutex_init(&mutexes[i]);
427
428    ret = sysdev_class_register(&rttest_sysclass);
429    if (ret)
430        return ret;
431
432    for (i = 0; i < MAX_RT_TEST_THREADS; i++) {
433        ret = init_test_thread(i);
434        if (ret)
435            break;
436        ret = sysdev_create_file(&thread_data[i].sysdev, &attr_status);
437        if (ret)
438            break;
439        ret = sysdev_create_file(&thread_data[i].sysdev, &attr_command);
440        if (ret)
441            break;
442    }
443
444    printk("Initializing RT-Tester: %s\n", ret ? "Failed" : "OK" );
445
446    return ret;
447}
448
449device_initcall(init_rttest);
450

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