FreeBSD/Linux Kernel Cross Reference
sys/sys/fail.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2009-2019 Dell EMC Isilon http://www.isilon.com/
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    /**
     * @file
     *
     * Main header for failpoint facility.
     */
    #ifndef _SYS_FAIL_H_
    #define _SYS_FAIL_H_
    
    #include <sys/param.h>
    #include <sys/cdefs.h>
    #include <sys/linker_set.h>
    #include <sys/queue.h>
    #include <sys/sysctl.h>
    #include <sys/condvar.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/systm.h>
    
    /**
     * Failpoint return codes, used internally.
     * @ingroup failpoint_private
     */
    enum fail_point_return_code {
            FAIL_POINT_RC_CONTINUE = 0,     /**< Continue with normal execution */
            FAIL_POINT_RC_RETURN,           /**< FP evaluated to 'return' */
            FAIL_POINT_RC_QUEUED,           /**< sleep_fn will be called */
    };
    
    struct fail_point_entry;
    struct fail_point_setting;
    
    /**
     * Internal failpoint structure, tracking all the current details of the
     * failpoint.  This structure is the core component shared between the
     * failure-injection code and the user-interface.
     * @ingroup failpoint_private
     */
    struct fail_point {
            const char *fp_name;            /* name of fail point */
            const char *fp_location;        /* file:line of fail point */
            volatile int fp_ref_cnt;        /**
                                         * protects fp_setting: while holding
                                         * a ref, fp_setting points to an
                                         * unfreed fail_point_setting
                                         */
            struct fail_point_setting * volatile fp_setting;
            int fp_flags;
    
            /**< Function to call before sleep or pause */
            void (*fp_pre_sleep_fn)(void *);
            /**< Arg for fp_pre_sleep_fn */
            void *fp_pre_sleep_arg;
    
            /**< Function to call after waking from sleep or pause */
            void (*fp_post_sleep_fn)(void *);
            /**< Arg for fp_post_sleep_fn */
            void *fp_post_sleep_arg;
    
            struct callout *fp_callout;
    };
    
    #define FAIL_POINT_DYNAMIC_NAME 0x01    /**< Must free name on destroy */
    /**< Use timeout path for sleep instead of msleep */
    #define FAIL_POINT_USE_TIMEOUT_PATH 0x02
    /**< If fail point is set to sleep, replace the sleep call with delay */
    #define FAIL_POINT_NONSLEEPABLE 0x04
    
    #define FAIL_POINT_CV_DESC "fp cv no iterators"
    #define FAIL_POINT_IS_OFF(fp) (__predict_true((fp)->fp_setting == NULL) || \
            __predict_true(fail_point_is_off(fp)))
   
   __BEGIN_DECLS
   
   /* Private failpoint eval function -- use fail_point_eval() instead. */
   enum fail_point_return_code fail_point_eval_nontrivial(struct fail_point *,
           int *ret);
   
   /**
    * @addtogroup failpoint
    * @{
    */
   /*
    * Initialize a fail-point.  The name is formed in printf-like fashion
    * from "fmt" and the subsequent arguments.
    * Pair with fail_point_destroy().
    */
   void fail_point_init(struct fail_point *, const char *fmt, ...)
       __printflike(2, 3);
   
   /* Return true iff this fail point is set to off, false otherwise */
   bool fail_point_is_off(struct fail_point *fp);
   
   /**
    * Set the pre-sleep function for a fail point
    * If fp_post_sleep_fn is specified, then FAIL_POINT_SLEEP will result in a
    * (*fp->fp_pre_sleep_fn)(fp->fp_pre_sleep_arg) call by the thread.
    */
   static inline void
   fail_point_sleep_set_pre_func(struct fail_point *fp, void (*sleep_fn)(void *))
   {
           fp->fp_pre_sleep_fn = sleep_fn;
   }
   
   static inline void
   fail_point_sleep_set_pre_arg(struct fail_point *fp, void *sleep_arg)
   {
           fp->fp_pre_sleep_arg = sleep_arg;
   }
   
   /**
    * Set the post-sleep function.  This will be passed to timeout if we take
    * the timeout path. This must be set if you sleep using the timeout path.
    */
   static inline void
   fail_point_sleep_set_post_func(struct fail_point *fp, void (*sleep_fn)(void *))
   {
           fp->fp_post_sleep_fn = sleep_fn;
   }
   
   static inline void
   fail_point_sleep_set_post_arg(struct fail_point *fp, void *sleep_arg)
   {
           fp->fp_post_sleep_arg = sleep_arg;
   }
   
   void fail_point_alloc_callout(struct fail_point *);
   
   /**
    * If the FAIL_POINT_USE_TIMEOUT flag is set on a failpoint, then
    * FAIL_POINT_SLEEP will result in a call to callout_reset instead of
    * msleep. Note that if you sleep while this flag is set, you must
    * set fp_post_sleep_fn or an error will occur upon waking.
    */
   static inline void
   fail_point_use_timeout_path(struct fail_point *fp, bool use_timeout,
           void (*post_sleep_fn)(void *))
   {
           KASSERT(!use_timeout || post_sleep_fn != NULL ||
                   (post_sleep_fn == NULL && fp->fp_post_sleep_fn != NULL),
                   ("Setting fp to use timeout, but not setting post_sleep_fn\n"));
   
           if (use_timeout) {
                   fail_point_alloc_callout(fp);
                   fp->fp_flags |= FAIL_POINT_USE_TIMEOUT_PATH;
           } else
                   fp->fp_flags &= ~FAIL_POINT_USE_TIMEOUT_PATH;
   
           if (post_sleep_fn != NULL)
                   fp->fp_post_sleep_fn = post_sleep_fn;
   }
   
   /**
    * Free the resources used by a fail-point.  Pair with fail_point_init().
    */
   void fail_point_destroy(struct fail_point *);
   
   /**
    * Evaluate a failpoint.
    */
   static inline enum fail_point_return_code
   fail_point_eval(struct fail_point *fp, int *ret)
   {
           if (__predict_true(fp->fp_setting == NULL))
                   return (FAIL_POINT_RC_CONTINUE);
           return (fail_point_eval_nontrivial(fp, ret));
   }
   
   __END_DECLS
   
   /* Declare a fail_point and its sysctl in a function. */
   #define KFAIL_POINT_DECLARE(name) \
       extern struct fail_point _FAIL_POINT_NAME(name)
   #define _FAIL_POINT_NAME(name) _fail_point_##name
   #define _FAIL_POINT_LOCATION() "(" __FILE__ ":" __XSTRING(__LINE__) ")"
   #define KFAIL_POINT_DEFINE(parent, name, flags) \
           struct fail_point _FAIL_POINT_NAME(name) = { \
                   .fp_name = #name, \
                   .fp_location = _FAIL_POINT_LOCATION(), \
                   .fp_ref_cnt = 0, \
                   .fp_setting = NULL, \
                   .fp_flags = (flags), \
                   .fp_pre_sleep_fn = NULL, \
                   .fp_pre_sleep_arg = NULL, \
                   .fp_post_sleep_fn = NULL, \
                   .fp_post_sleep_arg = NULL, \
           }; \
           SYSCTL_OID(parent, OID_AUTO, name, \
                   CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, \
                   &_FAIL_POINT_NAME(name), 0, fail_point_sysctl, \
                   "A", ""); \
           SYSCTL_OID(parent, OID_AUTO, status_##name, \
                   CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, \
                   &_FAIL_POINT_NAME(name), 0, \
                   fail_point_sysctl_status, "A", "");
   
   #define _FAIL_POINT_INIT(parent, name, flags) \
           static KFAIL_POINT_DEFINE(parent, name, flags)
   #define _FAIL_POINT_EVAL(name, cond, code...) \
           int RETURN_VALUE; \
    \
           if (__predict_false(cond && \
                   fail_point_eval(&_FAIL_POINT_NAME(name), &RETURN_VALUE))) { \
    \
                   code; \
    \
           }
   #define KFAIL_POINT_EVAL(name, code...) \
           _FAIL_POINT_EVAL(name, true, code)
   
   /**
    * Instantiate a failpoint which returns "RETURN_VALUE" from the function
    * when triggered.
    * @param parent  The parent sysctl under which to locate the fp's sysctl
    * @param name    The name of the failpoint in the sysctl tree (and printouts)
    * @return        Instantly returns the RETURN_VALUE specified in the
    *                failpoint, if triggered.
    */
   #define KFAIL_POINT_RETURN(parent, name) \
           KFAIL_POINT_CODE(parent, name, return RETURN_VALUE)
   
   /**
    * Instantiate a failpoint which returns (void) from the function when
    * triggered.
    * @param parent  The parent sysctl under which to locate the sysctl
    * @param name    The name of the failpoint in the sysctl tree (and printouts)
    * @return        Instantly returns void, if triggered in the failpoint.
    */
   #define KFAIL_POINT_RETURN_VOID(parent, name) \
           KFAIL_POINT_CODE(parent, name, return)
   
   /**
    * Instantiate a failpoint which sets an error when triggered.
    * @param parent     The parent sysctl under which to locate the sysctl
    * @param name       The name of the failpoint in the sysctl tree (and
    *                   printouts)
    * @param error_var  A variable to set to the failpoint's specified
    *                   return-value when triggered
    */
   #define KFAIL_POINT_ERROR(parent, name, error_var) \
           KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE)
   
   /**
    * Instantiate a failpoint which sets an error and then goes to a
    * specified label in the function when triggered.
    * @param parent     The parent sysctl under which to locate the sysctl
    * @param name       The name of the failpoint in the sysctl tree (and
    *                   printouts)
    * @param error_var  A variable to set to the failpoint's specified
    *                   return-value when triggered
    * @param label      The location to goto when triggered.
    */
   #define KFAIL_POINT_GOTO(parent, name, error_var, label) \
           KFAIL_POINT_CODE(parent, name, (error_var) = RETURN_VALUE; goto label)
   
   /**
    * Instantiate a failpoint which sets its pre- and post-sleep callback
    * mechanisms.
    * @param parent     The parent sysctl under which to locate the sysctl
    * @param name       The name of the failpoint in the sysctl tree (and
    *                   printouts)
    * @param pre_func   Function pointer to the pre-sleep function, which will be
    *                   called directly before going to sleep.
    * @param pre_arg    Argument to the pre-sleep function
    * @param post_func  Function pointer to the pot-sleep function, which will be
    *                   called directly before going to sleep.
    * @param post_arg   Argument to the post-sleep function
    */
   #define KFAIL_POINT_SLEEP_CALLBACKS(parent, name, pre_func, pre_arg, \
           post_func, post_arg) \
           KFAIL_POINT_CODE_SLEEP_CALLBACKS(parent, name, pre_func, \
               pre_arg, post_func, post_arg, return RETURN_VALUE)
   
   /**
    * Instantiate a failpoint which runs arbitrary code when triggered, and sets
    * its pre- and post-sleep callback mechanisms
    * @param parent     The parent sysctl under which to locate the sysctl
    * @param name       The name of the failpoint in the sysctl tree (and
    *                   printouts)
    * @param pre_func   Function pointer to the pre-sleep function, which will be
    *                   called directly before going to sleep.
    * @param pre_arg    Argument to the pre-sleep function
    * @param post_func  Function pointer to the pot-sleep function, which will be
    *                   called directly before going to sleep.
    * @param post_arg   Argument to the post-sleep function
    * @param code       The arbitrary code to run when triggered.  Can reference
    *                   "RETURN_VALUE" if desired to extract the specified
    *                   user return-value when triggered.  Note that this is
    *                   implemented with a do-while loop so be careful of
    *                   break and continue statements.
    */
   #define KFAIL_POINT_CODE_SLEEP_CALLBACKS(parent, name, pre_func, pre_arg, \
           post_func, post_arg, code...) \
           do { \
                   _FAIL_POINT_INIT(parent, name) \
                   _FAIL_POINT_NAME(name).fp_pre_sleep_fn = pre_func; \
                   _FAIL_POINT_NAME(name).fp_pre_sleep_arg = pre_arg; \
                   _FAIL_POINT_NAME(name).fp_post_sleep_fn = post_func; \
                   _FAIL_POINT_NAME(name).fp_post_sleep_arg = post_arg; \
                   _FAIL_POINT_EVAL(name, true, code) \
           } while (0)
   
   /**
    * Instantiate a failpoint which runs arbitrary code when triggered.
    * @param parent     The parent sysctl under which to locate the sysctl
    * @param name       The name of the failpoint in the sysctl tree
    *                   (and printouts)
    * @param code       The arbitrary code to run when triggered.  Can reference
    *                   "RETURN_VALUE" if desired to extract the specified
    *                   user return-value when triggered.  Note that this is
    *                   implemented with a do-while loop so be careful of
    *                   break and continue statements.
    */
   #define KFAIL_POINT_CODE(parent, name, code...) \
           do { \
                   _FAIL_POINT_INIT(parent, name, 0) \
                   _FAIL_POINT_EVAL(name, true, code) \
           } while (0)
   
   #define KFAIL_POINT_CODE_FLAGS(parent, name, flags, code...) \
           do { \
                   _FAIL_POINT_INIT(parent, name, flags) \
                   _FAIL_POINT_EVAL(name, true, code) \
           } while (0)
   
   #define KFAIL_POINT_CODE_COND(parent, name, cond, flags, code...) \
           do { \
                   _FAIL_POINT_INIT(parent, name, flags) \
                   _FAIL_POINT_EVAL(name, cond, code) \
           } while (0)
   
   /**
    * @}
    * (end group failpoint)
    */
   
   #ifdef _KERNEL
   int fail_point_sysctl(SYSCTL_HANDLER_ARGS);
   int fail_point_sysctl_status(SYSCTL_HANDLER_ARGS);
   
   /* The fail point sysctl tree. */
   SYSCTL_DECL(_debug_fail_point);
   #define DEBUG_FP        _debug_fail_point
   #endif
   
   #endif /* _SYS_FAIL_H_ */

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