lib/kunit/try-catch.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * An API to allow a function, that may fail, to be executed, and recover in a
   4  * controlled manner.
   5  *
   6  * Copyright (C) 2019, Google LLC.
   7  * Author: Brendan Higgins <brendanhiggins@google.com>
   8  */
   9
  10 #include <kunit/test.h>
  11 #include <linux/completion.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kthread.h>
  14 #include <linux/sched/task.h>
  15
  16 #include "try-catch-impl.h"
  17
  18 void __noreturn kunit_try_catch_throw(struct kunit_try_catch *try_catch)
  19 {
  20         try_catch->try_result = -EFAULT;
  21         kthread_exit(0);
  22 }
  23 EXPORT_SYMBOL_GPL(kunit_try_catch_throw);
  24
  25 static int kunit_generic_run_threadfn_adapter(void *data)
  26 {
  27         struct kunit_try_catch *try_catch = data;
  28
  29         try_catch->try_result = -EINTR;
  30         try_catch->try(try_catch->context);
  31         if (try_catch->try_result == -EINTR)
  32                 try_catch->try_result = 0;
  33
  34         return 0;
  35 }
  36
  37 static unsigned long kunit_test_timeout(void)
  38 {
  39         /*
  40          * TODO(brendanhiggins@google.com): We should probably have some type of
  41          * variable timeout here. The only question is what that timeout value
  42          * should be.
  43          *
  44          * The intention has always been, at some point, to be able to label
  45          * tests with some type of size bucket (unit/small, integration/medium,
  46          * large/system/end-to-end, etc), where each size bucket would get a
  47          * default timeout value kind of like what Bazel does:
  48          * https://docs.bazel.build/versions/master/be/common-definitions.html#test.size
  49          * There is still some debate to be had on exactly how we do this. (For
  50          * one, we probably want to have some sort of test runner level
  51          * timeout.)
  52          *
  53          * For more background on this topic, see:
  54          * https://mike-bland.com/2011/11/01/small-medium-large.html
  55          *
  56          * If tests timeout due to exceeding sysctl_hung_task_timeout_secs,
  57          * the task will be killed and an oops generated.
  58          */
  59         return 300 * msecs_to_jiffies(MSEC_PER_SEC); /* 5 min */
  60 }
  61
  62 void kunit_try_catch_run(struct kunit_try_catch *try_catch, void *context)
  63 {
  64         struct kunit *test = try_catch->test;
  65         struct task_struct *task_struct;
  66         struct completion *task_done;
  67         int exit_code, time_remaining;
  68
  69         try_catch->context = context;
  70         try_catch->try_result = 0;
  71         task_struct = kthread_create(kunit_generic_run_threadfn_adapter,
  72                                      try_catch, "kunit_try_catch_thread");
  73         if (IS_ERR(task_struct)) {
  74                 try_catch->try_result = PTR_ERR(task_struct);
  75                 try_catch->catch(try_catch->context);
  76                 return;
  77         }
  78         get_task_struct(task_struct);
  79         /*
  80          * As for a vfork(2), task_struct->vfork_done (pointing to the
  81          * underlying kthread->exited) can be used to wait for the end of a
  82          * kernel thread. It is set to NULL when the thread exits, so we
  83          * keep a copy here.
  84          */
  85         task_done = task_struct->vfork_done;
  86         wake_up_process(task_struct);
  87
  88         time_remaining = wait_for_completion_timeout(task_done,
  89                                                      kunit_test_timeout());
  90         if (time_remaining == 0) {
  91                 try_catch->try_result = -ETIMEDOUT;
  92                 kthread_stop(task_struct);
  93         }
  94
  95         put_task_struct(task_struct);
  96         exit_code = try_catch->try_result;
  97
  98         if (!exit_code)
  99                 return;
 100
 101         if (exit_code == -EFAULT)
 102                 try_catch->try_result = 0;
 103         else if (exit_code == -EINTR) {
 104                 if (test->last_seen.file)
 105                         kunit_err(test, "try faulted: last line seen %s:%d\n",
 106                                   test->last_seen.file, test->last_seen.line);
 107                 else
 108                         kunit_err(test, "try faulted\n");
 109         } else if (exit_code == -ETIMEDOUT)
 110                 kunit_err(test, "try timed out\n");
 111         else if (exit_code)
 112                 kunit_err(test, "Unknown error: %d\n", exit_code);
 113
 114         try_catch->catch(try_catch->context);
 115 }
 116 EXPORT_SYMBOL_GPL(kunit_try_catch_run);