The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/sys/fail.h

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    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: releng/11.1/sys/sys/fail.h 296927 2016-03-16 04:22:32Z cem $
   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/param.h>
   36 #include <sys/cdefs.h>
   37 #include <sys/linker_set.h>
   38 #include <sys/queue.h>
   39 #include <sys/sysctl.h>
   40 #include <sys/condvar.h>
   41 #include <sys/kernel.h>
   42 #include <sys/lock.h>
   43 #include <sys/mutex.h>
   44 #include <sys/systm.h>
   45 
   46 /**
   47  * Failpoint return codes, used internally.
   48  * @ingroup failpoint_private
   49  */
   50 enum fail_point_return_code {
   51         FAIL_POINT_RC_CONTINUE = 0,     /**< Continue with normal execution */
   52         FAIL_POINT_RC_RETURN,           /**< FP evaluated to 'return' */
   53         FAIL_POINT_RC_QUEUED,           /**< sleep_fn will be called */
   54 };
   55 
   56 struct fail_point_entry;
   57 struct fail_point_setting;
   58 
   59 /**
   60  * Internal failpoint structure, tracking all the current details of the
   61  * failpoint.  This structure is the core component shared between the
   62  * failure-injection code and the user-interface.
   63  * @ingroup failpoint_private
   64  */
   65 struct fail_point {
   66         const char *fp_name;            /* name of fail point */
   67         const char *fp_location;        /* file:line of fail point */
   68         volatile int fp_ref_cnt;        /**
   69                                      * protects fp_setting: while holding
   70                                      * a ref, fp_setting points to an
   71                                      * unfreed fail_point_setting
   72                                      */
   73         struct fail_point_setting * volatile fp_setting;
   74         int fp_flags;
   75 
   76         /**< Function to call before sleep or pause */
   77         void (*fp_pre_sleep_fn)(void *);
   78         /**< Arg for fp_pre_sleep_fn */
   79         void *fp_pre_sleep_arg;
   80 
   81         /**< Function to call after waking from sleep or pause */
   82         void (*fp_post_sleep_fn)(void *);
   83         /**< Arg for fp_post_sleep_fn */
   84         void *fp_post_sleep_arg;
   85 };
   86 
   87 #define FAIL_POINT_DYNAMIC_NAME 0x01    /**< Must free name on destroy */
   88 /**< Use timeout path for sleep instead of msleep */
   89 #define FAIL_POINT_USE_TIMEOUT_PATH 0x02
   90 /**< If fail point is set to sleep, replace the sleep call with delay */
   91 #define FAIL_POINT_NONSLEEPABLE 0x04
   92 
   93 #define FAIL_POINT_CV_DESC "fp cv no iterators"
   94 #define FAIL_POINT_IS_OFF(fp) (__predict_true((fp)->fp_setting == NULL) || \
   95         __predict_true(fail_point_is_off(fp)))
   96 
   97 __BEGIN_DECLS
   98 
   99 /* Private failpoint eval function -- use fail_point_eval() instead. */
  100 enum fail_point_return_code fail_point_eval_nontrivial(struct fail_point *,
  101         int *ret);
  102 
  103 /**
  104  * @addtogroup failpoint
  105  * @{
  106  */
  107 /*
  108  * Initialize a fail-point.  The name is formed in printf-like fashion
  109  * from "fmt" and the subsequent arguments.
  110  * Pair with fail_point_destroy().
  111  */
  112 void fail_point_init(struct fail_point *, const char *fmt, ...)
  113     __printflike(2, 3);
  114 
  115 /* Return true iff this fail point is set to off, false otherwise */
  116 bool fail_point_is_off(struct fail_point *fp);
  117 
  118 /**
  119  * Set the pre-sleep function for a fail point
  120  * If fp_post_sleep_fn is specified, then FAIL_POINT_SLEEP will result in a
  121  * (*fp->fp_pre_sleep_fn)(fp->fp_pre_sleep_arg) call by the thread.
  122  */
  123 static inline void
  124 fail_point_sleep_set_pre_func(struct fail_point *fp, void (*sleep_fn)(void *))
  125 {
  126         fp->fp_pre_sleep_fn = sleep_fn;
  127 }
  128 
  129 static inline void
  130 fail_point_sleep_set_pre_arg(struct fail_point *fp, void *sleep_arg)
  131 {
  132         fp->fp_pre_sleep_arg = sleep_arg;
  133 }
  134 
  135 /**
  136  * Set the post-sleep function.  This will be passed to timeout if we take
  137  * the timeout path. This must be set if you sleep using the timeout path.
  138  */
  139 static inline void
  140 fail_point_sleep_set_post_func(struct fail_point *fp, void (*sleep_fn)(void *))
  141 {
  142         fp->fp_post_sleep_fn = sleep_fn;
  143 }
  144 
  145 static inline void
  146 fail_point_sleep_set_post_arg(struct fail_point *fp, void *sleep_arg)
  147 {
  148         fp->fp_post_sleep_arg = sleep_arg;
  149 }
  150 /**
  151  * If the FAIL_POINT_USE_TIMEOUT flag is set on a failpoint, then
  152  * FAIL_POINT_SLEEP will result in a call to timeout instead of
  153  * msleep. Note that if you sleep while this flag is set, you must
  154  * set fp_post_sleep_fn or an error will occur upon waking.
  155  */
  156 static inline void
  157 fail_point_use_timeout_path(struct fail_point *fp, bool use_timeout,
  158         void (*post_sleep_fn)(void *))
  159 {
  160         KASSERT(!use_timeout || post_sleep_fn != NULL ||
  161                 (post_sleep_fn == NULL && fp->fp_post_sleep_fn != NULL),
  162                 ("Setting fp to use timeout, but not setting post_sleep_fn\n"));
  163 
  164         if (use_timeout)
  165                 fp->fp_flags |= FAIL_POINT_USE_TIMEOUT_PATH;
  166         else
  167                 fp->fp_flags &= ~FAIL_POINT_USE_TIMEOUT_PATH;
  168 
  169         if (post_sleep_fn != NULL)
  170                 fp->fp_post_sleep_fn = post_sleep_fn;
  171 }
  172 
  173 /**
  174  * Free the resources used by a fail-point.  Pair with fail_point_init().
  175  */
  176 void fail_point_destroy(struct fail_point *);
  177 
  178 /**
  179  * Evaluate a failpoint.
  180  */
  181 static inline enum fail_point_return_code
  182 fail_point_eval(struct fail_point *fp, int *ret)
  183 {
  184         if (__predict_true(fp->fp_setting == NULL))
  185                 return (FAIL_POINT_RC_CONTINUE);
  186         return (fail_point_eval_nontrivial(fp, ret));
  187 }
  188 
  189 __END_DECLS
  190 
  191 /* Declare a fail_point and its sysctl in a function. */
  192 #define _FAIL_POINT_NAME(name) _fail_point_##name
  193 #define _FAIL_POINT_LOCATION() "(" __FILE__ ":" __XSTRING(__LINE__) ")"
  194 #define _FAIL_POINT_INIT(parent, name, flags) \
  195         static struct fail_point _FAIL_POINT_NAME(name) = { \
  196                 .fp_name = #name, \
  197                 .fp_location = _FAIL_POINT_LOCATION(), \
  198                 .fp_ref_cnt = 0, \
  199                 .fp_setting = NULL, \
  200                 .fp_flags = (flags), \
  201                 .fp_pre_sleep_fn = NULL, \
  202                 .fp_pre_sleep_arg = NULL, \
  203                 .fp_post_sleep_fn = NULL, \
  204                 .fp_post_sleep_arg = NULL, \
  205         }; \
  206         SYSCTL_OID(parent, OID_AUTO, name, \
  207                 CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, \
  208                 &_FAIL_POINT_NAME(name), 0, fail_point_sysctl, \
  209                 "A", ""); \
  210         SYSCTL_OID(parent, OID_AUTO, status_##name, \
  211                 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, \
  212                 &_FAIL_POINT_NAME(name), 0, \
  213                 fail_point_sysctl_status, "A", "");
  214 #define _FAIL_POINT_EVAL(name, cond, code...) \
  215         int RETURN_VALUE; \
  216  \
  217         if (__predict_false(cond && \
  218                 fail_point_eval(&_FAIL_POINT_NAME(name), &RETURN_VALUE))) { \
  219  \
  220                 code; \
  221  \
  222         }
  223 
  224 
  225 /**
  226  * Instantiate a failpoint which returns "RETURN_VALUE" from the function
  227  * when triggered.
  228  * @param parent  The parent sysctl under which to locate the fp's sysctl
  229  * @param name    The name of the failpoint in the sysctl tree (and printouts)
  230  * @return        Instantly returns the RETURN_VALUE specified in the
  231  *                failpoint, if triggered.
  232  */
  233 #define KFAIL_POINT_RETURN(parent, name) \
  234         KFAIL_POINT_CODE(parent, name, return RETURN_VALUE)
  235 
  236 /**
  237  * Instantiate a failpoint which returns (void) from the function when
  238  * triggered.
  239  * @param parent  The parent sysctl under which to locate the sysctl
  240  * @param name    The name of the failpoint in the sysctl tree (and printouts)
  241  * @return        Instantly returns void, if triggered in the failpoint.
  242  */
  243 #define KFAIL_POINT_RETURN_VOID(parent, name) \
  244         KFAIL_POINT_CODE(parent, name, return)
  245 
  246 /**
  247  * Instantiate a failpoint which sets an error when triggered.
  248  * @param parent     The parent sysctl under which to locate the sysctl
  249  * @param name       The name of the failpoint in the sysctl tree (and
  250  *                   printouts)
  251  * @param error_var  A variable to set to the failpoint's specified
  252  *                   return-value when triggered
  253  */
  254 #define KFAIL_POINT_ERROR(parent, name, error_var) \
  255         KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE)
  256 
  257 /**
  258  * Instantiate a failpoint which sets an error and then goes to a
  259  * specified label in the function when triggered.
  260  * @param parent     The parent sysctl under which to locate the sysctl
  261  * @param name       The name of the failpoint in the sysctl tree (and
  262  *                   printouts)
  263  * @param error_var  A variable to set to the failpoint's specified
  264  *                   return-value when triggered
  265  * @param label      The location to goto when triggered.
  266  */
  267 #define KFAIL_POINT_GOTO(parent, name, error_var, label) \
  268         KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE; goto label)
  269 
  270 /**
  271  * Instantiate a failpoint which sets its pre- and post-sleep callback
  272  * mechanisms.
  273  * @param parent     The parent sysctl under which to locate the sysctl
  274  * @param name       The name of the failpoint in the sysctl tree (and
  275  *                   printouts)
  276  * @param pre_func   Function pointer to the pre-sleep function, which will be
  277  *                   called directly before going to sleep.
  278  * @param pre_arg    Argument to the pre-sleep function
  279  * @param post_func  Function pointer to the pot-sleep function, which will be
  280  *                   called directly before going to sleep.
  281  * @param post_arg   Argument to the post-sleep function
  282  */
  283 #define KFAIL_POINT_SLEEP_CALLBACKS(parent, name, pre_func, pre_arg, \
  284         post_func, post_arg) \
  285         KFAIL_POINT_CODE_SLEEP_CALLBACKS(parent, name, pre_func, \
  286             pre_arg, post_func, post_arg, return RETURN_VALUE)
  287 
  288 /**
  289  * Instantiate a failpoint which runs arbitrary code when triggered, and sets
  290  * its pre- and post-sleep callback mechanisms
  291  * @param parent     The parent sysctl under which to locate the sysctl
  292  * @param name       The name of the failpoint in the sysctl tree (and
  293  *                   printouts)
  294  * @param pre_func   Function pointer to the pre-sleep function, which will be
  295  *                   called directly before going to sleep.
  296  * @param pre_arg    Argument to the pre-sleep function
  297  * @param post_func  Function pointer to the pot-sleep function, which will be
  298  *                   called directly before going to sleep.
  299  * @param post_arg   Argument to the post-sleep function
  300  * @param code       The arbitrary code to run when triggered.  Can reference
  301  *                   "RETURN_VALUE" if desired to extract the specified
  302  *                   user return-value when triggered.  Note that this is
  303  *                   implemented with a do-while loop so be careful of
  304  *                   break and continue statements.
  305  */
  306 #define KFAIL_POINT_CODE_SLEEP_CALLBACKS(parent, name, pre_func, pre_arg, \
  307         post_func, post_arg, code...) \
  308         do { \
  309                 _FAIL_POINT_INIT(parent, name) \
  310                 _FAIL_POINT_NAME(name).fp_pre_sleep_fn = pre_func; \
  311                 _FAIL_POINT_NAME(name).fp_pre_sleep_arg = pre_arg; \
  312                 _FAIL_POINT_NAME(name).fp_post_sleep_fn = post_func; \
  313                 _FAIL_POINT_NAME(name).fp_post_sleep_arg = post_arg; \
  314                 _FAIL_POINT_EVAL(name, true, code) \
  315         } while (0)
  316 
  317 
  318 /**
  319  * Instantiate a failpoint which runs arbitrary code when triggered.
  320  * @param parent     The parent sysctl under which to locate the sysctl
  321  * @param name       The name of the failpoint in the sysctl tree
  322  *                   (and printouts)
  323  * @param code       The arbitrary code to run when triggered.  Can reference
  324  *                   "RETURN_VALUE" if desired to extract the specified
  325  *                   user return-value when triggered.  Note that this is
  326  *                   implemented with a do-while loop so be careful of
  327  *                   break and continue statements.
  328  */
  329 #define KFAIL_POINT_CODE(parent, name, code...) \
  330         do { \
  331                 _FAIL_POINT_INIT(parent, name, 0) \
  332                 _FAIL_POINT_EVAL(name, true, code) \
  333         } while (0)
  334 
  335 #define KFAIL_POINT_CODE_FLAGS(parent, name, flags, code...) \
  336         do { \
  337                 _FAIL_POINT_INIT(parent, name, flags) \
  338                 _FAIL_POINT_EVAL(name, true, code) \
  339         } while (0)
  340 
  341 #define KFAIL_POINT_CODE_COND(parent, name, cond, flags, code...) \
  342         do { \
  343                 _FAIL_POINT_INIT(parent, name, flags) \
  344                 _FAIL_POINT_EVAL(name, cond, code) \
  345         } while (0)
  346 
  347 /**
  348  * @}
  349  * (end group failpoint)
  350  */
  351 
  352 #ifdef _KERNEL
  353 int fail_point_sysctl(SYSCTL_HANDLER_ARGS);
  354 int fail_point_sysctl_status(SYSCTL_HANDLER_ARGS);
  355 
  356 /* The fail point sysctl tree. */
  357 SYSCTL_DECL(_debug_fail_point);
  358 #define DEBUG_FP        _debug_fail_point
  359 #endif
  360 
  361 #endif /* _SYS_FAIL_H_ */

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