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d745c852be
This means that their use is restricted to a single C file.
612 lines
15 KiB
C
612 lines
15 KiB
C
/*-
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* Copyright (c) 2009 Isilon Inc http://www.isilon.com/
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/**
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* @file
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*
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* fail(9) Facility.
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*
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* @ingroup failpoint_private
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*/
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/**
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* @defgroup failpoint fail(9) Facility
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*
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* Failpoints allow for injecting fake errors into running code on the fly,
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* without modifying code or recompiling with flags. Failpoints are always
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* present, and are very efficient when disabled. Failpoints are described
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* in man fail(9).
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*/
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/**
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* @defgroup failpoint_private Private fail(9) Implementation functions
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*
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* Private implementations for the actual failpoint code.
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*
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* @ingroup failpoint
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*/
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/**
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* @addtogroup failpoint_private
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* @{
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/ctype.h>
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#include <sys/errno.h>
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#include <sys/fail.h>
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#include <sys/kernel.h>
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#include <sys/libkern.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/sbuf.h>
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#include <machine/stdarg.h>
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#ifdef ILOG_DEFINE_FOR_FILE
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ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point);
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#endif
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static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system");
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#define fp_free(ptr) free(ptr, M_FAIL_POINT)
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#define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags))
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static struct mtx g_fp_mtx;
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MTX_SYSINIT(g_fp_mtx, &g_fp_mtx, "fail point mtx", MTX_DEF);
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#define FP_LOCK() mtx_lock(&g_fp_mtx)
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#define FP_UNLOCK() mtx_unlock(&g_fp_mtx)
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/**
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* Failpoint types.
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* Don't change these without changing fail_type_strings in fail.c.
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* @ingroup failpoint_private
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*/
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enum fail_point_t {
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FAIL_POINT_OFF, /**< don't fail */
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FAIL_POINT_PANIC, /**< panic */
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FAIL_POINT_RETURN, /**< return an errorcode */
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FAIL_POINT_BREAK, /**< break into the debugger */
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FAIL_POINT_PRINT, /**< print a message */
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FAIL_POINT_SLEEP, /**< sleep for some msecs */
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FAIL_POINT_NUMTYPES
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};
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static struct {
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const char *name;
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int nmlen;
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} fail_type_strings[] = {
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#define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 }
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[FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"),
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[FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"),
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[FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"),
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[FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"),
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[FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"),
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[FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"),
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};
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/**
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* Internal structure tracking a single term of a complete failpoint.
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* @ingroup failpoint_private
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*/
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struct fail_point_entry {
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enum fail_point_t fe_type; /**< type of entry */
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int fe_arg; /**< argument to type (e.g. return value) */
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int fe_prob; /**< likelihood of firing in millionths */
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int fe_count; /**< number of times to fire, 0 means always */
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pid_t fe_pid; /**< only fail for this process */
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TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */
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};
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static inline void
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fail_point_sleep(struct fail_point *fp, struct fail_point_entry *ent,
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int msecs, enum fail_point_return_code *pret)
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{
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/* convert from millisecs to ticks, rounding up */
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int timo = ((msecs * hz) + 999) / 1000;
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if (timo > 0) {
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if (fp->fp_sleep_fn == NULL) {
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msleep(fp, &g_fp_mtx, PWAIT, "failpt", timo);
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} else {
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timeout(fp->fp_sleep_fn, fp->fp_sleep_arg, timo);
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*pret = FAIL_POINT_RC_QUEUED;
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}
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}
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}
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/**
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* Defines stating the equivalent of probablilty one (100%)
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*/
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enum {
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PROB_MAX = 1000000, /* probability between zero and this number */
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PROB_DIGITS = 6, /* number of zero's in above number */
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};
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static char *parse_fail_point(struct fail_point_entries *, char *);
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static char *parse_term(struct fail_point_entries *, char *);
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static char *parse_number(int *out_units, int *out_decimal, char *);
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static char *parse_type(struct fail_point_entry *, char *);
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static void free_entry(struct fail_point_entries *, struct fail_point_entry *);
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static void clear_entries(struct fail_point_entries *);
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/**
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* Initialize a fail_point. The name is formed in a printf-like fashion
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* from "fmt" and subsequent arguments. This function is generally used
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* for custom failpoints located at odd places in the sysctl tree, and is
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* not explicitly needed for standard in-line-declared failpoints.
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*
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* @ingroup failpoint
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*/
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void
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fail_point_init(struct fail_point *fp, const char *fmt, ...)
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{
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va_list ap;
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char *name;
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int n;
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TAILQ_INIT(&fp->fp_entries);
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fp->fp_flags = 0;
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/* Figure out the size of the name. */
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va_start(ap, fmt);
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n = vsnprintf(NULL, 0, fmt, ap);
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va_end(ap);
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/* Allocate the name and fill it in. */
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name = fp_malloc(n + 1, M_WAITOK);
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if (name != NULL) {
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va_start(ap, fmt);
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vsnprintf(name, n + 1, fmt, ap);
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va_end(ap);
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}
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fp->fp_name = name;
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fp->fp_location = "";
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fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
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fp->fp_sleep_fn = NULL;
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fp->fp_sleep_arg = NULL;
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}
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/**
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* Free the resources held by a fail_point.
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*
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* @ingroup failpoint
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*/
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void
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fail_point_destroy(struct fail_point *fp)
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{
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if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
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fp_free(__DECONST(void *, fp->fp_name));
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fp->fp_name = NULL;
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}
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fp->fp_flags = 0;
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clear_entries(&fp->fp_entries);
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}
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/**
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* This does the real work of evaluating a fail point. If the fail point tells
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* us to return a value, this function returns 1 and fills in 'return_value'
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* (return_value is allowed to be null). If the fail point tells us to panic,
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* we never return. Otherwise we just return 0 after doing some work, which
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* means "keep going".
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*/
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enum fail_point_return_code
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fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
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{
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enum fail_point_return_code ret = FAIL_POINT_RC_CONTINUE;
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struct fail_point_entry *ent, *next;
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int msecs;
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FP_LOCK();
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TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, next) {
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int cont = 0; /* don't continue by default */
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if (ent->fe_prob < PROB_MAX &&
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ent->fe_prob < random() % PROB_MAX)
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continue;
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if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid)
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continue;
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switch (ent->fe_type) {
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case FAIL_POINT_PANIC:
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panic("fail point %s panicking", fp->fp_name);
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/* NOTREACHED */
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case FAIL_POINT_RETURN:
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if (return_value != NULL)
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*return_value = ent->fe_arg;
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ret = FAIL_POINT_RC_RETURN;
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break;
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case FAIL_POINT_BREAK:
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printf("fail point %s breaking to debugger\n",
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fp->fp_name);
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breakpoint();
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break;
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case FAIL_POINT_PRINT:
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printf("fail point %s executing\n", fp->fp_name);
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cont = ent->fe_arg;
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break;
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case FAIL_POINT_SLEEP:
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/*
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* Free the entry now if necessary, since
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* we're about to drop the mutex and sleep.
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*/
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msecs = ent->fe_arg;
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if (ent->fe_count > 0 && --ent->fe_count == 0) {
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free_entry(&fp->fp_entries, ent);
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ent = NULL;
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}
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if (msecs)
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fail_point_sleep(fp, ent, msecs, &ret);
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break;
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default:
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break;
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}
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if (ent != NULL && ent->fe_count > 0 && --ent->fe_count == 0)
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free_entry(&fp->fp_entries, ent);
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if (cont == 0)
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break;
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}
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/* Get rid of "off"s at the end. */
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while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
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ent->fe_type == FAIL_POINT_OFF)
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free_entry(&fp->fp_entries, ent);
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FP_UNLOCK();
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return (ret);
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}
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/**
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* Translate internal fail_point structure into human-readable text.
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*/
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static void
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fail_point_get(struct fail_point *fp, struct sbuf *sb)
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{
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struct fail_point_entry *ent;
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FP_LOCK();
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TAILQ_FOREACH(ent, &fp->fp_entries, fe_entries) {
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if (ent->fe_prob < PROB_MAX) {
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int decimal = ent->fe_prob % (PROB_MAX / 100);
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int units = ent->fe_prob / (PROB_MAX / 100);
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sbuf_printf(sb, "%d", units);
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if (decimal) {
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int digits = PROB_DIGITS - 2;
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while (!(decimal % 10)) {
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digits--;
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decimal /= 10;
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}
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sbuf_printf(sb, ".%0*d", digits, decimal);
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}
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sbuf_printf(sb, "%%");
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}
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if (ent->fe_count > 0)
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sbuf_printf(sb, "%d*", ent->fe_count);
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sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name);
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if (ent->fe_arg)
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sbuf_printf(sb, "(%d)", ent->fe_arg);
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if (ent->fe_pid != NO_PID)
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sbuf_printf(sb, "[pid %d]", ent->fe_pid);
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if (TAILQ_NEXT(ent, fe_entries))
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sbuf_printf(sb, "->");
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}
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if (TAILQ_EMPTY(&fp->fp_entries))
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sbuf_printf(sb, "off");
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FP_UNLOCK();
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}
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/**
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* Set an internal fail_point structure from a human-readable failpoint string
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* in a lock-safe manner.
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*/
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static int
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fail_point_set(struct fail_point *fp, char *buf)
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{
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int error = 0;
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struct fail_point_entry *ent, *ent_next;
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struct fail_point_entries new_entries;
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/* Parse new entries. */
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TAILQ_INIT(&new_entries);
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if (!parse_fail_point(&new_entries, buf)) {
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clear_entries(&new_entries);
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error = EINVAL;
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goto end;
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}
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FP_LOCK();
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/* Move new entries in. */
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TAILQ_SWAP(&fp->fp_entries, &new_entries, fail_point_entry, fe_entries);
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clear_entries(&new_entries);
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/* Get rid of useless zero probability entries. */
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TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, ent_next) {
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if (ent->fe_prob == 0)
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free_entry(&fp->fp_entries, ent);
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}
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/* Get rid of "off"s at the end. */
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while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
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ent->fe_type == FAIL_POINT_OFF)
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free_entry(&fp->fp_entries, ent);
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FP_UNLOCK();
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end:
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#ifdef IWARNING
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if (error)
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IWARNING("Failed to set %s %s to %s",
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fp->fp_name, fp->fp_location, buf);
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else
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INOTICE("Set %s %s to %s",
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fp->fp_name, fp->fp_location, buf);
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#endif /* IWARNING */
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return (error);
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}
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#define MAX_FAIL_POINT_BUF 1023
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/**
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* Handle kernel failpoint set/get.
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*/
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int
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fail_point_sysctl(SYSCTL_HANDLER_ARGS)
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{
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struct fail_point *fp = arg1;
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char *buf = NULL;
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struct sbuf sb;
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int error;
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/* Retrieving */
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sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
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fail_point_get(fp, &sb);
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sbuf_trim(&sb);
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sbuf_finish(&sb);
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error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
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sbuf_delete(&sb);
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/* Setting */
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if (!error && req->newptr) {
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if (req->newlen > MAX_FAIL_POINT_BUF) {
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error = EINVAL;
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goto out;
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}
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buf = fp_malloc(req->newlen + 1, M_WAITOK);
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error = SYSCTL_IN(req, buf, req->newlen);
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if (error)
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goto out;
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buf[req->newlen] = '\0';
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error = fail_point_set(fp, buf);
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}
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out:
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fp_free(buf);
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return (error);
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}
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/**
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* Internal helper function to translate a human-readable failpoint string
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* into a internally-parsable fail_point structure.
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*/
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static char *
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parse_fail_point(struct fail_point_entries *ents, char *p)
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{
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/* <fail_point> ::
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* <term> ( "->" <term> )*
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*/
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p = parse_term(ents, p);
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if (p == NULL)
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return (NULL);
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while (*p != '\0') {
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if (p[0] != '-' || p[1] != '>')
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return (NULL);
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p = parse_term(ents, p + 2);
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if (p == NULL)
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return (NULL);
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}
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return (p);
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}
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/**
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* Internal helper function to parse an individual term from a failpoint.
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*/
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static char *
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parse_term(struct fail_point_entries *ents, char *p)
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{
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struct fail_point_entry *ent;
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ent = fp_malloc(sizeof *ent, M_WAITOK | M_ZERO);
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ent->fe_prob = PROB_MAX;
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ent->fe_pid = NO_PID;
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TAILQ_INSERT_TAIL(ents, ent, fe_entries);
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/*
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* <term> ::
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* ( (<float> "%") | (<integer> "*" ) )*
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* <type>
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* [ "(" <integer> ")" ]
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* [ "[pid " <integer> "]" ]
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*/
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/* ( (<float> "%") | (<integer> "*" ) )* */
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while (isdigit(*p) || *p == '.') {
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int units, decimal;
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p = parse_number(&units, &decimal, p);
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if (p == NULL)
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return (NULL);
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if (*p == '%') {
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if (units > 100) /* prevent overflow early */
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units = 100;
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ent->fe_prob = units * (PROB_MAX / 100) + decimal;
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if (ent->fe_prob > PROB_MAX)
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ent->fe_prob = PROB_MAX;
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} else if (*p == '*') {
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if (!units || decimal)
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return (NULL);
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ent->fe_count = units;
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} else
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return (NULL);
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p++;
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}
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/* <type> */
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p = parse_type(ent, p);
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if (p == NULL)
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return (NULL);
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if (*p == '\0')
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return (p);
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/* [ "(" <integer> ")" ] */
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if (*p != '(')
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return p;
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p++;
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if (!isdigit(*p) && *p != '-')
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return (NULL);
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ent->fe_arg = strtol(p, &p, 0);
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if (*p++ != ')')
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return (NULL);
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/* [ "[pid " <integer> "]" ] */
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#define PID_STRING "[pid "
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if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0)
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return (p);
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p += sizeof(PID_STRING) - 1;
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if (!isdigit(*p))
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return (NULL);
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ent->fe_pid = strtol(p, &p, 0);
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if (*p++ != ']')
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|
return (NULL);
|
|
|
|
return (p);
|
|
}
|
|
|
|
/**
|
|
* Internal helper function to parse a numeric for a failpoint term.
|
|
*/
|
|
static char *
|
|
parse_number(int *out_units, int *out_decimal, char *p)
|
|
{
|
|
char *old_p;
|
|
|
|
/*
|
|
* <number> ::
|
|
* <integer> [ "." <integer> ] |
|
|
* "." <integer>
|
|
*/
|
|
|
|
/* whole part */
|
|
old_p = p;
|
|
*out_units = strtol(p, &p, 10);
|
|
if (p == old_p && *p != '.')
|
|
return (NULL);
|
|
|
|
/* fractional part */
|
|
*out_decimal = 0;
|
|
if (*p == '.') {
|
|
int digits = 0;
|
|
p++;
|
|
while (isdigit(*p)) {
|
|
int digit = *p - '0';
|
|
if (digits < PROB_DIGITS - 2)
|
|
*out_decimal = *out_decimal * 10 + digit;
|
|
else if (digits == PROB_DIGITS - 2 && digit >= 5)
|
|
(*out_decimal)++;
|
|
digits++;
|
|
p++;
|
|
}
|
|
if (!digits) /* need at least one digit after '.' */
|
|
return (NULL);
|
|
while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */
|
|
*out_decimal *= 10;
|
|
}
|
|
|
|
return (p); /* success */
|
|
}
|
|
|
|
/**
|
|
* Internal helper function to parse an individual type for a failpoint term.
|
|
*/
|
|
static char *
|
|
parse_type(struct fail_point_entry *ent, char *beg)
|
|
{
|
|
enum fail_point_t type;
|
|
int len;
|
|
|
|
for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) {
|
|
len = fail_type_strings[type].nmlen;
|
|
if (strncmp(fail_type_strings[type].name, beg, len) == 0) {
|
|
ent->fe_type = type;
|
|
return (beg + len);
|
|
}
|
|
}
|
|
return (NULL);
|
|
}
|
|
|
|
/**
|
|
* Internal helper function to free an individual failpoint term.
|
|
*/
|
|
static void
|
|
free_entry(struct fail_point_entries *ents, struct fail_point_entry *ent)
|
|
{
|
|
TAILQ_REMOVE(ents, ent, fe_entries);
|
|
fp_free(ent);
|
|
}
|
|
|
|
/**
|
|
* Internal helper function to clear out all failpoint terms for a single
|
|
* failpoint.
|
|
*/
|
|
static void
|
|
clear_entries(struct fail_point_entries *ents)
|
|
{
|
|
struct fail_point_entry *ent, *ent_next;
|
|
|
|
TAILQ_FOREACH_SAFE(ent, ents, fe_entries, ent_next)
|
|
fp_free(ent);
|
|
TAILQ_INIT(ents);
|
|
}
|
|
|
|
/* The fail point sysctl tree. */
|
|
SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points");
|