sys/sys/fail.h

   1 /*-
   2  * Copyright (c) 2009 Isilon Inc http://www.isilon.com/
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $FreeBSD$
  26  */
  27 /**
  28  * @file
  29  *
  30  * Main header for failpoint facility.
  31  */
  32 #ifndef _SYS_FAIL_H_
  33 #define _SYS_FAIL_H_
  34
  35 #include <sys/types.h>
  36
  37 #include <sys/linker_set.h>
  38 #include <sys/param.h>
  39 #include <sys/queue.h>
  40 #include <sys/sysctl.h>
  41
  42
  43 /**
  44  * Failpoint types.
  45  * Don't change these without changing fail_type_strings in fail.c.
  46  * @ingroup failpoint_private
  47  */
  48 enum fail_point_t {
  49         FAIL_POINT_OFF,         /**< don't fail */
  50         FAIL_POINT_PANIC,       /**< panic */
  51         FAIL_POINT_RETURN,      /**< return an errorcode */
  52         FAIL_POINT_BREAK,       /**< break into the debugger */
  53         FAIL_POINT_PRINT,       /**< print a message */
  54         FAIL_POINT_SLEEP,       /**< sleep for some msecs */
  55         FAIL_POINT_INVALID,     /**< placeholder */
  56 };
  57
  58 /**
  59  * Failpoint return codes, used internally.
  60  * @ingroup failpoint_private
  61  */
  62 enum fail_point_return_code {
  63         FAIL_POINT_RC_CONTINUE = 0,     /**< Continue with normal execution */
  64         FAIL_POINT_RC_RETURN,           /**< FP evaluated to 'return' */
  65         FAIL_POINT_RC_QUEUED,           /**< sleep_fn will be called */
  66 };
  67
  68 TAILQ_HEAD(fail_point_entries, fail_point_entry);
  69 /**
  70  * Internal failpoint structure, tracking all the current details of the
  71  * failpoint.  This structure is the core component shared between the
  72  * failure-injection code and the user-interface.
  73  * @ingroup failpoint_private
  74  */
  75 struct fail_point {
  76         const char *fp_name;            /**< name of fail point */
  77         const char *fp_location;        /**< file:line of fail point */
  78         struct fail_point_entries fp_entries;   /**< list of entries */
  79         int fp_flags;
  80         void (*fp_sleep_fn)(void *);    /**< Function to call at end of
  81                                          * sleep for sleep failpoints */
  82         void *fp_sleep_arg;             /**< Arg for sleep_fn */
  83 };
  84
  85 #define FAIL_POINT_DYNAMIC_NAME 0x01    /**< Must free name on destroy */
  86
  87 /**
  88  * Internal structure tracking a single term of a complete failpoint.
  89  * @ingroup failpoint_private
  90  */
  91 struct fail_point_entry {
  92         enum fail_point_t fe_type;      /**< type of entry */
  93         int             fe_arg;         /**< argument to type (e.g. return value) */
  94         int             fe_prob;        /**< likelihood of firing in millionths */
  95         int             fe_count;       /**< number of times to fire, 0 means always */
  96
  97         TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */
  98 };
  99
 100 /* Private failpoint eval function -- use fail_point_eval() instead. */
 101 enum fail_point_return_code fail_point_eval_nontrivial(struct fail_point *,
 102         int *ret);
 103
 104 /**
 105  * @addtogroup failpoint
 106  * @{
 107  */
 108 /*
 109  * Initialize a fail-point.  The name is formed in printf-like fashion
 110  * from "fmt" and the subsequent arguments.
 111  * Pair with fail_point_destroy().
 112  */
 113 void fail_point_init(struct fail_point *, const char *fmt, ...)
 114     __printflike(2, 3);
 115
 116 /**
 117  * Set the sleep function for a fail point
 118  * If sleep_fn is specified, then FAIL_POINT_SLEEP will result in a
 119  * (*fp->sleep_fn)(fp->sleep_arg) call by the timer thread.  Otherwise,
 120  * if sleep_fn is NULL (default), then FAIL_POINT_SLEEP will result in the
 121  * fail_point_eval() call sleeping.
 122  */
 123 static __inline void
 124 fail_point_sleep_set_func(struct fail_point *fp, void (*sleep_fn)(void *))
 125 {
 126         fp->fp_sleep_fn = sleep_fn;
 127 }
 128
 129 /**
 130  * Set the argument for the sleep function for a fail point
 131  */
 132 static __inline void
 133 fail_point_sleep_set_arg(struct fail_point *fp, void *sleep_arg)
 134 {
 135         fp->fp_sleep_arg = sleep_arg;
 136 }
 137
 138 /**
 139  * Free the resources used by a fail-point.  Pair with fail_point_init().
 140  */
 141 void fail_point_destroy(struct fail_point *);
 142
 143 /**
 144  * Evaluate a failpoint.
 145  */
 146 static __inline enum fail_point_return_code
 147 fail_point_eval(struct fail_point *fp, int *ret)
 148 {
 149         if (TAILQ_EMPTY(&fp->fp_entries)) {
 150                 return (FAIL_POINT_RC_CONTINUE);
 151         }
 152         return (fail_point_eval_nontrivial(fp, ret));
 153 }
 154
 155 /* Declare a fail_point and its sysctl in a function. */
 156 #define _FAIL_POINT_NAME(name) _fail_point_##name
 157 #define _STRINGIFY_HELPER(x) #x
 158 #define _STRINGIFY(x) _STRINGIFY_HELPER(x)
 159 #define _FAIL_POINT_LOCATION() __FILE__ ":" _STRINGIFY(__LINE__)
 160
 161 /**
 162  * Instantiate a failpoint which returns "value" from the function when triggered.
 163  * @param parent  The parent sysctl under which to locate the sysctl
 164  * @param name    The name of the failpoint in the sysctl tree (and printouts)
 165  * @return        Instantly returns the return("value") specified in the
 166  *                failpoint, if triggered.
 167  */
 168 #define KFAIL_POINT_RETURN(parent, name) \
 169         KFAIL_POINT_CODE(parent, name, return RETURN_VALUE)
 170
 171 /**
 172  * Instantiate a failpoint which returns (void) from the function when triggered.
 173  * @param parent  The parent sysctl under which to locate the sysctl
 174  * @param name    The name of the failpoint in the sysctl tree (and printouts)
 175  * @return        Instantly returns void, if triggered in the failpoint.
 176  */
 177 #define KFAIL_POINT_RETURN_VOID(parent, name) \
 178         KFAIL_POINT_CODE(parent, name, return)
 179
 180 /**
 181  * Instantiate a failpoint which sets an error when triggered.
 182  * @param parent     The parent sysctl under which to locate the sysctl
 183  * @param name       The name of the failpoint in the sysctl tree (and printouts)
 184  * @param error_var  A variable to set to the failpoint's specified
 185  *                   return-value when triggered
 186  */
 187 #define KFAIL_POINT_ERROR(parent, name, error_var) \
 188         KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE)
 189
 190 /**
 191  * Instantiate a failpoint which sets an error and then goes to a
 192  * specified label in the function when triggered.
 193  * @param parent     The parent sysctl under which to locate the sysctl
 194  * @param name       The name of the failpoint in the sysctl tree (and printouts)
 195  * @param error_var  A variable to set to the failpoint's specified
 196  *                   return-value when triggered
 197  * @param label      The location to goto when triggered.
 198  */
 199 #define KFAIL_POINT_GOTO(parent, name, error_var, label) \
 200         KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE; goto label)
 201
 202 /**
 203  * Instantiate a failpoint which runs arbitrary code when triggered.
 204  * @param parent     The parent sysctl under which to locate the sysctl
 205  * @param name       The name of the failpoint in the sysctl tree (and printouts)
 206  * @param code       The arbitrary code to run when triggered.  Can reference
 207  *                   "RETURN_VALUE" if desired to extract the specified user
 208  *                   return-value when triggered
 209  */
 210 #define KFAIL_POINT_CODE(parent, name, code)                            \
 211         KFAIL_POINT_START(parent, name) {                               \
 212                 code;                                                   \
 213         } FAIL_POINT_END
 214
 215 /**
 216  * @}
 217  * (end group failpoint)
 218  */
 219
 220 /**
 221  * Internal macro to implement above #defines -- should not be used directly.
 222  * @ingroup failpoint_private
 223  */
 224 #define KFAIL_POINT_START(parent, name)                                 \
 225         do {                                                            \
 226                 int RETURN_VALUE;                                       \
 227                 static struct fail_point _FAIL_POINT_NAME(name) = {     \
 228                         #name,                                          \
 229                         _FAIL_POINT_LOCATION(),                         \
 230                         TAILQ_HEAD_INITIALIZER(                         \
 231                                 _FAIL_POINT_NAME(name).fp_entries),     \
 232                         0,                                              \
 233                         NULL, NULL,                                     \
 234                 };                                                      \
 235                 SYSCTL_OID(parent, OID_AUTO, name,                      \
 236                         CTLTYPE_STRING | CTLFLAG_RW,                    \
 237                         &_FAIL_POINT_NAME(name), 0, fail_point_sysctl,  \
 238                         "A", "");                                       \
 239                                                                         \
 240                 if (__predict_false(                                    \
 241                     fail_point_eval(&_FAIL_POINT_NAME(name),            \
 242                     &RETURN_VALUE))) {
 243
 244 /**
 245  * Internal macro to implement above #defines -- should not be used directly.
 246  * @ingroup failpoint_private
 247  */
 248 #define FAIL_POINT_END                                                  \
 249                 }                                                       \
 250         } while (0)
 251
 252 #ifdef _KERNEL
 253 int fail_point_sysctl(SYSCTL_HANDLER_ARGS);
 254
 255 /* The fail point sysctl tree. */
 256 SYSCTL_DECL(_debug_fail_point);
 257 #endif
 258 #define DEBUG_FP _debug_fail_point
 259
 260 #endif /* _SYS_FAIL_H_ */