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Linux/lib/test_kmod.c

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  1 /*
  2  * kmod stress test driver
  3  *
  4  * Copyright (C) 2017 Luis R. Rodriguez <mcgrof@kernel.org>
  5  *
  6  * This program is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License as published by the Free
  8  * Software Foundation; either version 2 of the License, or at your option any
  9  * later version; or, when distributed separately from the Linux kernel or
 10  * when incorporated into other software packages, subject to the following
 11  * license:
 12  *
 13  * This program is free software; you can redistribute it and/or modify it
 14  * under the terms of copyleft-next (version 0.3.1 or later) as published
 15  * at http://copyleft-next.org/.
 16  */
 17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 18 
 19 /*
 20  * This driver provides an interface to trigger and test the kernel's
 21  * module loader through a series of configurations and a few triggers.
 22  * To test this driver use the following script as root:
 23  *
 24  * tools/testing/selftests/kmod/kmod.sh --help
 25  */
 26 
 27 #include <linux/kernel.h>
 28 #include <linux/module.h>
 29 #include <linux/kmod.h>
 30 #include <linux/printk.h>
 31 #include <linux/kthread.h>
 32 #include <linux/sched.h>
 33 #include <linux/fs.h>
 34 #include <linux/miscdevice.h>
 35 #include <linux/vmalloc.h>
 36 #include <linux/slab.h>
 37 #include <linux/device.h>
 38 
 39 #define TEST_START_NUM_THREADS  50
 40 #define TEST_START_DRIVER       "test_module"
 41 #define TEST_START_TEST_FS      "xfs"
 42 #define TEST_START_TEST_CASE    TEST_KMOD_DRIVER
 43 
 44 
 45 static bool force_init_test = false;
 46 module_param(force_init_test, bool_enable_only, 0644);
 47 MODULE_PARM_DESC(force_init_test,
 48                  "Force kicking a test immediately after driver loads");
 49 
 50 /*
 51  * For device allocation / registration
 52  */
 53 static DEFINE_MUTEX(reg_dev_mutex);
 54 static LIST_HEAD(reg_test_devs);
 55 
 56 /*
 57  * num_test_devs actually represents the *next* ID of the next
 58  * device we will allow to create.
 59  */
 60 static int num_test_devs;
 61 
 62 /**
 63  * enum kmod_test_case - linker table test case
 64  *
 65  * If you add a  test case, please be sure to review if you need to se
 66  * @need_mod_put for your tests case.
 67  *
 68  * @TEST_KMOD_DRIVER: stress tests request_module()
 69  * @TEST_KMOD_FS_TYPE: stress tests get_fs_type()
 70  */
 71 enum kmod_test_case {
 72         __TEST_KMOD_INVALID = 0,
 73 
 74         TEST_KMOD_DRIVER,
 75         TEST_KMOD_FS_TYPE,
 76 
 77         __TEST_KMOD_MAX,
 78 };
 79 
 80 struct test_config {
 81         char *test_driver;
 82         char *test_fs;
 83         unsigned int num_threads;
 84         enum kmod_test_case test_case;
 85         int test_result;
 86 };
 87 
 88 struct kmod_test_device;
 89 
 90 /**
 91  * kmod_test_device_info - thread info
 92  *
 93  * @ret_sync: return value if request_module() is used, sync request for
 94  *      @TEST_KMOD_DRIVER
 95  * @fs_sync: return value of get_fs_type() for @TEST_KMOD_FS_TYPE
 96  * @thread_idx: thread ID
 97  * @test_dev: test device test is being performed under
 98  * @need_mod_put: Some tests (get_fs_type() is one) requires putting the module
 99  *      (module_put(fs_sync->owner)) when done, otherwise you will not be able
100  *      to unload the respective modules and re-test. We use this to keep
101  *      accounting of when we need this and to help out in case we need to
102  *      error out and deal with module_put() on error.
103  */
104 struct kmod_test_device_info {
105         int ret_sync;
106         struct file_system_type *fs_sync;
107         struct task_struct *task_sync;
108         unsigned int thread_idx;
109         struct kmod_test_device *test_dev;
110         bool need_mod_put;
111 };
112 
113 /**
114  * kmod_test_device - test device to help test kmod
115  *
116  * @dev_idx: unique ID for test device
117  * @config: configuration for the test
118  * @misc_dev: we use a misc device under the hood
119  * @dev: pointer to misc_dev's own struct device
120  * @config_mutex: protects configuration of test
121  * @trigger_mutex: the test trigger can only be fired once at a time
122  * @thread_lock: protects @done count, and the @info per each thread
123  * @done: number of threads which have completed or failed
124  * @test_is_oom: when we run out of memory, use this to halt moving forward
125  * @kthreads_done: completion used to signal when all work is done
126  * @list: needed to be part of the reg_test_devs
127  * @info: array of info for each thread
128  */
129 struct kmod_test_device {
130         int dev_idx;
131         struct test_config config;
132         struct miscdevice misc_dev;
133         struct device *dev;
134         struct mutex config_mutex;
135         struct mutex trigger_mutex;
136         struct mutex thread_mutex;
137 
138         unsigned int done;
139 
140         bool test_is_oom;
141         struct completion kthreads_done;
142         struct list_head list;
143 
144         struct kmod_test_device_info *info;
145 };
146 
147 static const char *test_case_str(enum kmod_test_case test_case)
148 {
149         switch (test_case) {
150         case TEST_KMOD_DRIVER:
151                 return "TEST_KMOD_DRIVER";
152         case TEST_KMOD_FS_TYPE:
153                 return "TEST_KMOD_FS_TYPE";
154         default:
155                 return "invalid";
156         }
157 }
158 
159 static struct miscdevice *dev_to_misc_dev(struct device *dev)
160 {
161         return dev_get_drvdata(dev);
162 }
163 
164 static struct kmod_test_device *misc_dev_to_test_dev(struct miscdevice *misc_dev)
165 {
166         return container_of(misc_dev, struct kmod_test_device, misc_dev);
167 }
168 
169 static struct kmod_test_device *dev_to_test_dev(struct device *dev)
170 {
171         struct miscdevice *misc_dev;
172 
173         misc_dev = dev_to_misc_dev(dev);
174 
175         return misc_dev_to_test_dev(misc_dev);
176 }
177 
178 /* Must run with thread_mutex held */
179 static void kmod_test_done_check(struct kmod_test_device *test_dev,
180                                  unsigned int idx)
181 {
182         struct test_config *config = &test_dev->config;
183 
184         test_dev->done++;
185         dev_dbg(test_dev->dev, "Done thread count: %u\n", test_dev->done);
186 
187         if (test_dev->done == config->num_threads) {
188                 dev_info(test_dev->dev, "Done: %u threads have all run now\n",
189                          test_dev->done);
190                 dev_info(test_dev->dev, "Last thread to run: %u\n", idx);
191                 complete(&test_dev->kthreads_done);
192         }
193 }
194 
195 static void test_kmod_put_module(struct kmod_test_device_info *info)
196 {
197         struct kmod_test_device *test_dev = info->test_dev;
198         struct test_config *config = &test_dev->config;
199 
200         if (!info->need_mod_put)
201                 return;
202 
203         switch (config->test_case) {
204         case TEST_KMOD_DRIVER:
205                 break;
206         case TEST_KMOD_FS_TYPE:
207                 if (info->fs_sync && info->fs_sync->owner)
208                         module_put(info->fs_sync->owner);
209                 break;
210         default:
211                 BUG();
212         }
213 
214         info->need_mod_put = true;
215 }
216 
217 static int run_request(void *data)
218 {
219         struct kmod_test_device_info *info = data;
220         struct kmod_test_device *test_dev = info->test_dev;
221         struct test_config *config = &test_dev->config;
222 
223         switch (config->test_case) {
224         case TEST_KMOD_DRIVER:
225                 info->ret_sync = request_module("%s", config->test_driver);
226                 break;
227         case TEST_KMOD_FS_TYPE:
228                 info->fs_sync = get_fs_type(config->test_fs);
229                 info->need_mod_put = true;
230                 break;
231         default:
232                 /* __trigger_config_run() already checked for test sanity */
233                 BUG();
234                 return -EINVAL;
235         }
236 
237         dev_dbg(test_dev->dev, "Ran thread %u\n", info->thread_idx);
238 
239         test_kmod_put_module(info);
240 
241         mutex_lock(&test_dev->thread_mutex);
242         info->task_sync = NULL;
243         kmod_test_done_check(test_dev, info->thread_idx);
244         mutex_unlock(&test_dev->thread_mutex);
245 
246         return 0;
247 }
248 
249 static int tally_work_test(struct kmod_test_device_info *info)
250 {
251         struct kmod_test_device *test_dev = info->test_dev;
252         struct test_config *config = &test_dev->config;
253         int err_ret = 0;
254 
255         switch (config->test_case) {
256         case TEST_KMOD_DRIVER:
257                 /*
258                  * Only capture errors, if one is found that's
259                  * enough, for now.
260                  */
261                 if (info->ret_sync != 0)
262                         err_ret = info->ret_sync;
263                 dev_info(test_dev->dev,
264                          "Sync thread %d return status: %d\n",
265                          info->thread_idx, info->ret_sync);
266                 break;
267         case TEST_KMOD_FS_TYPE:
268                 /* For now we make this simple */
269                 if (!info->fs_sync)
270                         err_ret = -EINVAL;
271                 dev_info(test_dev->dev, "Sync thread %u fs: %s\n",
272                          info->thread_idx, info->fs_sync ? config->test_fs :
273                          "NULL");
274                 break;
275         default:
276                 BUG();
277         }
278 
279         return err_ret;
280 }
281 
282 /*
283  * XXX: add result option to display if all errors did not match.
284  * For now we just keep any error code if one was found.
285  *
286  * If this ran it means *all* tasks were created fine and we
287  * are now just collecting results.
288  *
289  * Only propagate errors, do not override with a subsequent sucess case.
290  */
291 static void tally_up_work(struct kmod_test_device *test_dev)
292 {
293         struct test_config *config = &test_dev->config;
294         struct kmod_test_device_info *info;
295         unsigned int idx;
296         int err_ret = 0;
297         int ret = 0;
298 
299         mutex_lock(&test_dev->thread_mutex);
300 
301         dev_info(test_dev->dev, "Results:\n");
302 
303         for (idx=0; idx < config->num_threads; idx++) {
304                 info = &test_dev->info[idx];
305                 ret = tally_work_test(info);
306                 if (ret)
307                         err_ret = ret;
308         }
309 
310         /*
311          * Note: request_module() returns 256 for a module not found even
312          * though modprobe itself returns 1.
313          */
314         config->test_result = err_ret;
315 
316         mutex_unlock(&test_dev->thread_mutex);
317 }
318 
319 static int try_one_request(struct kmod_test_device *test_dev, unsigned int idx)
320 {
321         struct kmod_test_device_info *info = &test_dev->info[idx];
322         int fail_ret = -ENOMEM;
323 
324         mutex_lock(&test_dev->thread_mutex);
325 
326         info->thread_idx = idx;
327         info->test_dev = test_dev;
328         info->task_sync = kthread_run(run_request, info, "%s-%u",
329                                       KBUILD_MODNAME, idx);
330 
331         if (!info->task_sync || IS_ERR(info->task_sync)) {
332                 test_dev->test_is_oom = true;
333                 dev_err(test_dev->dev, "Setting up thread %u failed\n", idx);
334                 info->task_sync = NULL;
335                 goto err_out;
336         } else
337                 dev_dbg(test_dev->dev, "Kicked off thread %u\n", idx);
338 
339         mutex_unlock(&test_dev->thread_mutex);
340 
341         return 0;
342 
343 err_out:
344         info->ret_sync = fail_ret;
345         mutex_unlock(&test_dev->thread_mutex);
346 
347         return fail_ret;
348 }
349 
350 static void test_dev_kmod_stop_tests(struct kmod_test_device *test_dev)
351 {
352         struct test_config *config = &test_dev->config;
353         struct kmod_test_device_info *info;
354         unsigned int i;
355 
356         dev_info(test_dev->dev, "Ending request_module() tests\n");
357 
358         mutex_lock(&test_dev->thread_mutex);
359 
360         for (i=0; i < config->num_threads; i++) {
361                 info = &test_dev->info[i];
362                 if (info->task_sync && !IS_ERR(info->task_sync)) {
363                         dev_info(test_dev->dev,
364                                  "Stopping still-running thread %i\n", i);
365                         kthread_stop(info->task_sync);
366                 }
367 
368                 /*
369                  * info->task_sync is well protected, it can only be
370                  * NULL or a pointer to a struct. If its NULL we either
371                  * never ran, or we did and we completed the work. Completed
372                  * tasks *always* put the module for us. This is a sanity
373                  * check -- just in case.
374                  */
375                 if (info->task_sync && info->need_mod_put)
376                         test_kmod_put_module(info);
377         }
378 
379         mutex_unlock(&test_dev->thread_mutex);
380 }
381 
382 /*
383  * Only wait *iff* we did not run into any errors during all of our thread
384  * set up. If run into any issues we stop threads and just bail out with
385  * an error to the trigger. This also means we don't need any tally work
386  * for any threads which fail.
387  */
388 static int try_requests(struct kmod_test_device *test_dev)
389 {
390         struct test_config *config = &test_dev->config;
391         unsigned int idx;
392         int ret;
393         bool any_error = false;
394 
395         for (idx=0; idx < config->num_threads; idx++) {
396                 if (test_dev->test_is_oom) {
397                         any_error = true;
398                         break;
399                 }
400 
401                 ret = try_one_request(test_dev, idx);
402                 if (ret) {
403                         any_error = true;
404                         break;
405                 }
406         }
407 
408         if (!any_error) {
409                 test_dev->test_is_oom = false;
410                 dev_info(test_dev->dev,
411                          "No errors were found while initializing threads\n");
412                 wait_for_completion(&test_dev->kthreads_done);
413                 tally_up_work(test_dev);
414         } else {
415                 test_dev->test_is_oom = true;
416                 dev_info(test_dev->dev,
417                          "At least one thread failed to start, stop all work\n");
418                 test_dev_kmod_stop_tests(test_dev);
419                 return -ENOMEM;
420         }
421 
422         return 0;
423 }
424 
425 static int run_test_driver(struct kmod_test_device *test_dev)
426 {
427         struct test_config *config = &test_dev->config;
428 
429         dev_info(test_dev->dev, "Test case: %s (%u)\n",
430                  test_case_str(config->test_case),
431                  config->test_case);
432         dev_info(test_dev->dev, "Test driver to load: %s\n",
433                  config->test_driver);
434         dev_info(test_dev->dev, "Number of threads to run: %u\n",
435                  config->num_threads);
436         dev_info(test_dev->dev, "Thread IDs will range from 0 - %u\n",
437                  config->num_threads - 1);
438 
439         return try_requests(test_dev);
440 }
441 
442 static int run_test_fs_type(struct kmod_test_device *test_dev)
443 {
444         struct test_config *config = &test_dev->config;
445 
446         dev_info(test_dev->dev, "Test case: %s (%u)\n",
447                  test_case_str(config->test_case),
448                  config->test_case);
449         dev_info(test_dev->dev, "Test filesystem to load: %s\n",
450                  config->test_fs);
451         dev_info(test_dev->dev, "Number of threads to run: %u\n",
452                  config->num_threads);
453         dev_info(test_dev->dev, "Thread IDs will range from 0 - %u\n",
454                  config->num_threads - 1);
455 
456         return try_requests(test_dev);
457 }
458 
459 static ssize_t config_show(struct device *dev,
460                            struct device_attribute *attr,
461                            char *buf)
462 {
463         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
464         struct test_config *config = &test_dev->config;
465         int len = 0;
466 
467         mutex_lock(&test_dev->config_mutex);
468 
469         len += snprintf(buf, PAGE_SIZE,
470                         "Custom trigger configuration for: %s\n",
471                         dev_name(dev));
472 
473         len += snprintf(buf+len, PAGE_SIZE - len,
474                         "Number of threads:\t%u\n",
475                         config->num_threads);
476 
477         len += snprintf(buf+len, PAGE_SIZE - len,
478                         "Test_case:\t%s (%u)\n",
479                         test_case_str(config->test_case),
480                         config->test_case);
481 
482         if (config->test_driver)
483                 len += snprintf(buf+len, PAGE_SIZE - len,
484                                 "driver:\t%s\n",
485                                 config->test_driver);
486         else
487                 len += snprintf(buf+len, PAGE_SIZE - len,
488                                 "driver:\tEMPTY\n");
489 
490         if (config->test_fs)
491                 len += snprintf(buf+len, PAGE_SIZE - len,
492                                 "fs:\t%s\n",
493                                 config->test_fs);
494         else
495                 len += snprintf(buf+len, PAGE_SIZE - len,
496                                 "fs:\tEMPTY\n");
497 
498         mutex_unlock(&test_dev->config_mutex);
499 
500         return len;
501 }
502 static DEVICE_ATTR_RO(config);
503 
504 /*
505  * This ensures we don't allow kicking threads through if our configuration
506  * is faulty.
507  */
508 static int __trigger_config_run(struct kmod_test_device *test_dev)
509 {
510         struct test_config *config = &test_dev->config;
511 
512         test_dev->done = 0;
513 
514         switch (config->test_case) {
515         case TEST_KMOD_DRIVER:
516                 return run_test_driver(test_dev);
517         case TEST_KMOD_FS_TYPE:
518                 return run_test_fs_type(test_dev);
519         default:
520                 dev_warn(test_dev->dev,
521                          "Invalid test case requested: %u\n",
522                          config->test_case);
523                 return -EINVAL;
524         }
525 }
526 
527 static int trigger_config_run(struct kmod_test_device *test_dev)
528 {
529         struct test_config *config = &test_dev->config;
530         int ret;
531 
532         mutex_lock(&test_dev->trigger_mutex);
533         mutex_lock(&test_dev->config_mutex);
534 
535         ret = __trigger_config_run(test_dev);
536         if (ret < 0)
537                 goto out;
538         dev_info(test_dev->dev, "General test result: %d\n",
539                  config->test_result);
540 
541         /*
542          * We must return 0 after a trigger even unless something went
543          * wrong with the setup of the test. If the test setup went fine
544          * then userspace must just check the result of config->test_result.
545          * One issue with relying on the return from a call in the kernel
546          * is if the kernel returns a possitive value using this trigger
547          * will not return the value to userspace, it would be lost.
548          *
549          * By not relying on capturing the return value of tests we are using
550          * through the trigger it also us to run tests with set -e and only
551          * fail when something went wrong with the driver upon trigger
552          * requests.
553          */
554         ret = 0;
555 
556 out:
557         mutex_unlock(&test_dev->config_mutex);
558         mutex_unlock(&test_dev->trigger_mutex);
559 
560         return ret;
561 }
562 
563 static ssize_t
564 trigger_config_store(struct device *dev,
565                      struct device_attribute *attr,
566                      const char *buf, size_t count)
567 {
568         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
569         int ret;
570 
571         if (test_dev->test_is_oom)
572                 return -ENOMEM;
573 
574         /* For all intents and purposes we don't care what userspace
575          * sent this trigger, we care only that we were triggered.
576          * We treat the return value only for caputuring issues with
577          * the test setup. At this point all the test variables should
578          * have been allocated so typically this should never fail.
579          */
580         ret = trigger_config_run(test_dev);
581         if (unlikely(ret < 0))
582                 goto out;
583 
584         /*
585          * Note: any return > 0 will be treated as success
586          * and the error value will not be available to userspace.
587          * Do not rely on trying to send to userspace a test value
588          * return value as possitive return errors will be lost.
589          */
590         if (WARN_ON(ret > 0))
591                 return -EINVAL;
592 
593         ret = count;
594 out:
595         return ret;
596 }
597 static DEVICE_ATTR_WO(trigger_config);
598 
599 /*
600  * XXX: move to kstrncpy() once merged.
601  *
602  * Users should use kfree_const() when freeing these.
603  */
604 static int __kstrncpy(char **dst, const char *name, size_t count, gfp_t gfp)
605 {
606         *dst = kstrndup(name, count, gfp);
607         if (!*dst)
608                 return -ENOSPC;
609         return count;
610 }
611 
612 static int config_copy_test_driver_name(struct test_config *config,
613                                     const char *name,
614                                     size_t count)
615 {
616         return __kstrncpy(&config->test_driver, name, count, GFP_KERNEL);
617 }
618 
619 
620 static int config_copy_test_fs(struct test_config *config, const char *name,
621                                size_t count)
622 {
623         return __kstrncpy(&config->test_fs, name, count, GFP_KERNEL);
624 }
625 
626 static void __kmod_config_free(struct test_config *config)
627 {
628         if (!config)
629                 return;
630 
631         kfree_const(config->test_driver);
632         config->test_driver = NULL;
633 
634         kfree_const(config->test_fs);
635         config->test_fs = NULL;
636 }
637 
638 static void kmod_config_free(struct kmod_test_device *test_dev)
639 {
640         struct test_config *config;
641 
642         if (!test_dev)
643                 return;
644 
645         config = &test_dev->config;
646 
647         mutex_lock(&test_dev->config_mutex);
648         __kmod_config_free(config);
649         mutex_unlock(&test_dev->config_mutex);
650 }
651 
652 static ssize_t config_test_driver_store(struct device *dev,
653                                         struct device_attribute *attr,
654                                         const char *buf, size_t count)
655 {
656         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
657         struct test_config *config = &test_dev->config;
658         int copied;
659 
660         mutex_lock(&test_dev->config_mutex);
661 
662         kfree_const(config->test_driver);
663         config->test_driver = NULL;
664 
665         copied = config_copy_test_driver_name(config, buf, count);
666         mutex_unlock(&test_dev->config_mutex);
667 
668         return copied;
669 }
670 
671 /*
672  * As per sysfs_kf_seq_show() the buf is max PAGE_SIZE.
673  */
674 static ssize_t config_test_show_str(struct mutex *config_mutex,
675                                     char *dst,
676                                     char *src)
677 {
678         int len;
679 
680         mutex_lock(config_mutex);
681         len = snprintf(dst, PAGE_SIZE, "%s\n", src);
682         mutex_unlock(config_mutex);
683 
684         return len;
685 }
686 
687 static ssize_t config_test_driver_show(struct device *dev,
688                                         struct device_attribute *attr,
689                                         char *buf)
690 {
691         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
692         struct test_config *config = &test_dev->config;
693 
694         return config_test_show_str(&test_dev->config_mutex, buf,
695                                     config->test_driver);
696 }
697 static DEVICE_ATTR_RW(config_test_driver);
698 
699 static ssize_t config_test_fs_store(struct device *dev,
700                                     struct device_attribute *attr,
701                                     const char *buf, size_t count)
702 {
703         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
704         struct test_config *config = &test_dev->config;
705         int copied;
706 
707         mutex_lock(&test_dev->config_mutex);
708 
709         kfree_const(config->test_fs);
710         config->test_fs = NULL;
711 
712         copied = config_copy_test_fs(config, buf, count);
713         mutex_unlock(&test_dev->config_mutex);
714 
715         return copied;
716 }
717 
718 static ssize_t config_test_fs_show(struct device *dev,
719                                    struct device_attribute *attr,
720                                    char *buf)
721 {
722         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
723         struct test_config *config = &test_dev->config;
724 
725         return config_test_show_str(&test_dev->config_mutex, buf,
726                                     config->test_fs);
727 }
728 static DEVICE_ATTR_RW(config_test_fs);
729 
730 static int trigger_config_run_type(struct kmod_test_device *test_dev,
731                                    enum kmod_test_case test_case,
732                                    const char *test_str)
733 {
734         int copied = 0;
735         struct test_config *config = &test_dev->config;
736 
737         mutex_lock(&test_dev->config_mutex);
738 
739         switch (test_case) {
740         case TEST_KMOD_DRIVER:
741                 kfree_const(config->test_driver);
742                 config->test_driver = NULL;
743                 copied = config_copy_test_driver_name(config, test_str,
744                                                       strlen(test_str));
745                 break;
746         case TEST_KMOD_FS_TYPE:
747                 kfree_const(config->test_fs);
748                 config->test_fs = NULL;
749                 copied = config_copy_test_fs(config, test_str,
750                                              strlen(test_str));
751                 break;
752         default:
753                 mutex_unlock(&test_dev->config_mutex);
754                 return -EINVAL;
755         }
756 
757         config->test_case = test_case;
758 
759         mutex_unlock(&test_dev->config_mutex);
760 
761         if (copied <= 0 || copied != strlen(test_str)) {
762                 test_dev->test_is_oom = true;
763                 return -ENOMEM;
764         }
765 
766         test_dev->test_is_oom = false;
767 
768         return trigger_config_run(test_dev);
769 }
770 
771 static void free_test_dev_info(struct kmod_test_device *test_dev)
772 {
773         vfree(test_dev->info);
774         test_dev->info = NULL;
775 }
776 
777 static int kmod_config_sync_info(struct kmod_test_device *test_dev)
778 {
779         struct test_config *config = &test_dev->config;
780 
781         free_test_dev_info(test_dev);
782         test_dev->info =
783                 vzalloc(array_size(sizeof(struct kmod_test_device_info),
784                                    config->num_threads));
785         if (!test_dev->info)
786                 return -ENOMEM;
787 
788         return 0;
789 }
790 
791 /*
792  * Old kernels may not have this, if you want to port this code to
793  * test it on older kernels.
794  */
795 #ifdef get_kmod_umh_limit
796 static unsigned int kmod_init_test_thread_limit(void)
797 {
798         return get_kmod_umh_limit();
799 }
800 #else
801 static unsigned int kmod_init_test_thread_limit(void)
802 {
803         return TEST_START_NUM_THREADS;
804 }
805 #endif
806 
807 static int __kmod_config_init(struct kmod_test_device *test_dev)
808 {
809         struct test_config *config = &test_dev->config;
810         int ret = -ENOMEM, copied;
811 
812         __kmod_config_free(config);
813 
814         copied = config_copy_test_driver_name(config, TEST_START_DRIVER,
815                                               strlen(TEST_START_DRIVER));
816         if (copied != strlen(TEST_START_DRIVER))
817                 goto err_out;
818 
819         copied = config_copy_test_fs(config, TEST_START_TEST_FS,
820                                      strlen(TEST_START_TEST_FS));
821         if (copied != strlen(TEST_START_TEST_FS))
822                 goto err_out;
823 
824         config->num_threads = kmod_init_test_thread_limit();
825         config->test_result = 0;
826         config->test_case = TEST_START_TEST_CASE;
827 
828         ret = kmod_config_sync_info(test_dev);
829         if (ret)
830                 goto err_out;
831 
832         test_dev->test_is_oom = false;
833 
834         return 0;
835 
836 err_out:
837         test_dev->test_is_oom = true;
838         WARN_ON(test_dev->test_is_oom);
839 
840         __kmod_config_free(config);
841 
842         return ret;
843 }
844 
845 static ssize_t reset_store(struct device *dev,
846                            struct device_attribute *attr,
847                            const char *buf, size_t count)
848 {
849         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
850         int ret;
851 
852         mutex_lock(&test_dev->trigger_mutex);
853         mutex_lock(&test_dev->config_mutex);
854 
855         ret = __kmod_config_init(test_dev);
856         if (ret < 0) {
857                 ret = -ENOMEM;
858                 dev_err(dev, "could not alloc settings for config trigger: %d\n",
859                        ret);
860                 goto out;
861         }
862 
863         dev_info(dev, "reset\n");
864         ret = count;
865 
866 out:
867         mutex_unlock(&test_dev->config_mutex);
868         mutex_unlock(&test_dev->trigger_mutex);
869 
870         return ret;
871 }
872 static DEVICE_ATTR_WO(reset);
873 
874 static int test_dev_config_update_uint_sync(struct kmod_test_device *test_dev,
875                                             const char *buf, size_t size,
876                                             unsigned int *config,
877                                             int (*test_sync)(struct kmod_test_device *test_dev))
878 {
879         int ret;
880         unsigned long new;
881         unsigned int old_val;
882 
883         ret = kstrtoul(buf, 10, &new);
884         if (ret)
885                 return ret;
886 
887         if (new > UINT_MAX)
888                 return -EINVAL;
889 
890         mutex_lock(&test_dev->config_mutex);
891 
892         old_val = *config;
893         *(unsigned int *)config = new;
894 
895         ret = test_sync(test_dev);
896         if (ret) {
897                 *(unsigned int *)config = old_val;
898 
899                 ret = test_sync(test_dev);
900                 WARN_ON(ret);
901 
902                 mutex_unlock(&test_dev->config_mutex);
903                 return -EINVAL;
904         }
905 
906         mutex_unlock(&test_dev->config_mutex);
907         /* Always return full write size even if we didn't consume all */
908         return size;
909 }
910 
911 static int test_dev_config_update_uint_range(struct kmod_test_device *test_dev,
912                                              const char *buf, size_t size,
913                                              unsigned int *config,
914                                              unsigned int min,
915                                              unsigned int max)
916 {
917         int ret;
918         unsigned long new;
919 
920         ret = kstrtoul(buf, 10, &new);
921         if (ret)
922                 return ret;
923 
924         if (new < min || new > max)
925                 return -EINVAL;
926 
927         mutex_lock(&test_dev->config_mutex);
928         *config = new;
929         mutex_unlock(&test_dev->config_mutex);
930 
931         /* Always return full write size even if we didn't consume all */
932         return size;
933 }
934 
935 static int test_dev_config_update_int(struct kmod_test_device *test_dev,
936                                       const char *buf, size_t size,
937                                       int *config)
938 {
939         int ret;
940         long new;
941 
942         ret = kstrtol(buf, 10, &new);
943         if (ret)
944                 return ret;
945 
946         if (new < INT_MIN || new > INT_MAX)
947                 return -EINVAL;
948 
949         mutex_lock(&test_dev->config_mutex);
950         *config = new;
951         mutex_unlock(&test_dev->config_mutex);
952         /* Always return full write size even if we didn't consume all */
953         return size;
954 }
955 
956 static ssize_t test_dev_config_show_int(struct kmod_test_device *test_dev,
957                                         char *buf,
958                                         int config)
959 {
960         int val;
961 
962         mutex_lock(&test_dev->config_mutex);
963         val = config;
964         mutex_unlock(&test_dev->config_mutex);
965 
966         return snprintf(buf, PAGE_SIZE, "%d\n", val);
967 }
968 
969 static ssize_t test_dev_config_show_uint(struct kmod_test_device *test_dev,
970                                          char *buf,
971                                          unsigned int config)
972 {
973         unsigned int val;
974 
975         mutex_lock(&test_dev->config_mutex);
976         val = config;
977         mutex_unlock(&test_dev->config_mutex);
978 
979         return snprintf(buf, PAGE_SIZE, "%u\n", val);
980 }
981 
982 static ssize_t test_result_store(struct device *dev,
983                                  struct device_attribute *attr,
984                                  const char *buf, size_t count)
985 {
986         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
987         struct test_config *config = &test_dev->config;
988 
989         return test_dev_config_update_int(test_dev, buf, count,
990                                           &config->test_result);
991 }
992 
993 static ssize_t config_num_threads_store(struct device *dev,
994                                         struct device_attribute *attr,
995                                         const char *buf, size_t count)
996 {
997         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
998         struct test_config *config = &test_dev->config;
999 
1000         return test_dev_config_update_uint_sync(test_dev, buf, count,
1001                                                 &config->num_threads,
1002                                                 kmod_config_sync_info);
1003 }
1004 
1005 static ssize_t config_num_threads_show(struct device *dev,
1006                                        struct device_attribute *attr,
1007                                        char *buf)
1008 {
1009         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
1010         struct test_config *config = &test_dev->config;
1011 
1012         return test_dev_config_show_int(test_dev, buf, config->num_threads);
1013 }
1014 static DEVICE_ATTR_RW(config_num_threads);
1015 
1016 static ssize_t config_test_case_store(struct device *dev,
1017                                       struct device_attribute *attr,
1018                                       const char *buf, size_t count)
1019 {
1020         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
1021         struct test_config *config = &test_dev->config;
1022 
1023         return test_dev_config_update_uint_range(test_dev, buf, count,
1024                                                  &config->test_case,
1025                                                  __TEST_KMOD_INVALID + 1,
1026                                                  __TEST_KMOD_MAX - 1);
1027 }
1028 
1029 static ssize_t config_test_case_show(struct device *dev,
1030                                      struct device_attribute *attr,
1031                                      char *buf)
1032 {
1033         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
1034         struct test_config *config = &test_dev->config;
1035 
1036         return test_dev_config_show_uint(test_dev, buf, config->test_case);
1037 }
1038 static DEVICE_ATTR_RW(config_test_case);
1039 
1040 static ssize_t test_result_show(struct device *dev,
1041                                 struct device_attribute *attr,
1042                                 char *buf)
1043 {
1044         struct kmod_test_device *test_dev = dev_to_test_dev(dev);
1045         struct test_config *config = &test_dev->config;
1046 
1047         return test_dev_config_show_int(test_dev, buf, config->test_result);
1048 }
1049 static DEVICE_ATTR_RW(test_result);
1050 
1051 #define TEST_KMOD_DEV_ATTR(name)                &dev_attr_##name.attr
1052 
1053 static struct attribute *test_dev_attrs[] = {
1054         TEST_KMOD_DEV_ATTR(trigger_config),
1055         TEST_KMOD_DEV_ATTR(config),
1056         TEST_KMOD_DEV_ATTR(reset),
1057 
1058         TEST_KMOD_DEV_ATTR(config_test_driver),
1059         TEST_KMOD_DEV_ATTR(config_test_fs),
1060         TEST_KMOD_DEV_ATTR(config_num_threads),
1061         TEST_KMOD_DEV_ATTR(config_test_case),
1062         TEST_KMOD_DEV_ATTR(test_result),
1063 
1064         NULL,
1065 };
1066 
1067 ATTRIBUTE_GROUPS(test_dev);
1068 
1069 static int kmod_config_init(struct kmod_test_device *test_dev)
1070 {
1071         int ret;
1072 
1073         mutex_lock(&test_dev->config_mutex);
1074         ret = __kmod_config_init(test_dev);
1075         mutex_unlock(&test_dev->config_mutex);
1076 
1077         return ret;
1078 }
1079 
1080 static struct kmod_test_device *alloc_test_dev_kmod(int idx)
1081 {
1082         int ret;
1083         struct kmod_test_device *test_dev;
1084         struct miscdevice *misc_dev;
1085 
1086         test_dev = vzalloc(sizeof(struct kmod_test_device));
1087         if (!test_dev)
1088                 goto err_out;
1089 
1090         mutex_init(&test_dev->config_mutex);
1091         mutex_init(&test_dev->trigger_mutex);
1092         mutex_init(&test_dev->thread_mutex);
1093 
1094         init_completion(&test_dev->kthreads_done);
1095 
1096         ret = kmod_config_init(test_dev);
1097         if (ret < 0) {
1098                 pr_err("Cannot alloc kmod_config_init()\n");
1099                 goto err_out_free;
1100         }
1101 
1102         test_dev->dev_idx = idx;
1103         misc_dev = &test_dev->misc_dev;
1104 
1105         misc_dev->minor = MISC_DYNAMIC_MINOR;
1106         misc_dev->name = kasprintf(GFP_KERNEL, "test_kmod%d", idx);
1107         if (!misc_dev->name) {
1108                 pr_err("Cannot alloc misc_dev->name\n");
1109                 goto err_out_free_config;
1110         }
1111         misc_dev->groups = test_dev_groups;
1112 
1113         return test_dev;
1114 
1115 err_out_free_config:
1116         free_test_dev_info(test_dev);
1117         kmod_config_free(test_dev);
1118 err_out_free:
1119         vfree(test_dev);
1120         test_dev = NULL;
1121 err_out:
1122         return NULL;
1123 }
1124 
1125 static void free_test_dev_kmod(struct kmod_test_device *test_dev)
1126 {
1127         if (test_dev) {
1128                 kfree_const(test_dev->misc_dev.name);
1129                 test_dev->misc_dev.name = NULL;
1130                 free_test_dev_info(test_dev);
1131                 kmod_config_free(test_dev);
1132                 vfree(test_dev);
1133                 test_dev = NULL;
1134         }
1135 }
1136 
1137 static struct kmod_test_device *register_test_dev_kmod(void)
1138 {
1139         struct kmod_test_device *test_dev = NULL;
1140         int ret;
1141 
1142         mutex_lock(&reg_dev_mutex);
1143 
1144         /* int should suffice for number of devices, test for wrap */
1145         if (num_test_devs + 1 == INT_MAX) {
1146                 pr_err("reached limit of number of test devices\n");
1147                 goto out;
1148         }
1149 
1150         test_dev = alloc_test_dev_kmod(num_test_devs);
1151         if (!test_dev)
1152                 goto out;
1153 
1154         ret = misc_register(&test_dev->misc_dev);
1155         if (ret) {
1156                 pr_err("could not register misc device: %d\n", ret);
1157                 free_test_dev_kmod(test_dev);
1158                 goto out;
1159         }
1160 
1161         test_dev->dev = test_dev->misc_dev.this_device;
1162         list_add_tail(&test_dev->list, &reg_test_devs);
1163         dev_info(test_dev->dev, "interface ready\n");
1164 
1165         num_test_devs++;
1166 
1167 out:
1168         mutex_unlock(&reg_dev_mutex);
1169 
1170         return test_dev;
1171 
1172 }
1173 
1174 static int __init test_kmod_init(void)
1175 {
1176         struct kmod_test_device *test_dev;
1177         int ret;
1178 
1179         test_dev = register_test_dev_kmod();
1180         if (!test_dev) {
1181                 pr_err("Cannot add first test kmod device\n");
1182                 return -ENODEV;
1183         }
1184 
1185         /*
1186          * With some work we might be able to gracefully enable
1187          * testing with this driver built-in, for now this seems
1188          * rather risky. For those willing to try have at it,
1189          * and enable the below. Good luck! If that works, try
1190          * lowering the init level for more fun.
1191          */
1192         if (force_init_test) {
1193                 ret = trigger_config_run_type(test_dev,
1194                                               TEST_KMOD_DRIVER, "tun");
1195                 if (WARN_ON(ret))
1196                         return ret;
1197                 ret = trigger_config_run_type(test_dev,
1198                                               TEST_KMOD_FS_TYPE, "btrfs");
1199                 if (WARN_ON(ret))
1200                         return ret;
1201         }
1202 
1203         return 0;
1204 }
1205 late_initcall(test_kmod_init);
1206 
1207 static
1208 void unregister_test_dev_kmod(struct kmod_test_device *test_dev)
1209 {
1210         mutex_lock(&test_dev->trigger_mutex);
1211         mutex_lock(&test_dev->config_mutex);
1212 
1213         test_dev_kmod_stop_tests(test_dev);
1214 
1215         dev_info(test_dev->dev, "removing interface\n");
1216         misc_deregister(&test_dev->misc_dev);
1217 
1218         mutex_unlock(&test_dev->config_mutex);
1219         mutex_unlock(&test_dev->trigger_mutex);
1220 
1221         free_test_dev_kmod(test_dev);
1222 }
1223 
1224 static void __exit test_kmod_exit(void)
1225 {
1226         struct kmod_test_device *test_dev, *tmp;
1227 
1228         mutex_lock(&reg_dev_mutex);
1229         list_for_each_entry_safe(test_dev, tmp, &reg_test_devs, list) {
1230                 list_del(&test_dev->list);
1231                 unregister_test_dev_kmod(test_dev);
1232         }
1233         mutex_unlock(&reg_dev_mutex);
1234 }
1235 module_exit(test_kmod_exit);
1236 
1237 MODULE_AUTHOR("Luis R. Rodriguez <mcgrof@kernel.org>");
1238 MODULE_LICENSE("GPL");
1239 

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