svn commit: r192908 - in head: share/man/man9 sys/conf sys/kern
sys/sys
Zachary Loafman
zml at FreeBSD.org
Wed May 27 16:36:58 UTC 2009
Author: zml
Date: Wed May 27 16:36:54 2009
New Revision: 192908
URL: http://svn.freebsd.org/changeset/base/192908
Log:
fail(9) support:
Add support for kernel fault injection using KFAIL_POINT_* macros and
fail_point_* infrastructure. Add example fail point in vfs_bio.c to
simulate VM buf pressure.
Approved by: dfr (mentor)
Added:
head/share/man/man9/fail.9 (contents, props changed)
head/sys/kern/kern_fail.c (contents, props changed)
head/sys/sys/fail.h (contents, props changed)
Modified:
head/share/man/man9/Makefile
head/sys/conf/files
head/sys/kern/vfs_bio.c
head/sys/sys/queue.h
Modified: head/share/man/man9/Makefile
==============================================================================
--- head/share/man/man9/Makefile Wed May 27 16:34:08 2009 (r192907)
+++ head/share/man/man9/Makefile Wed May 27 16:36:54 2009 (r192908)
@@ -99,6 +99,7 @@ MAN= accept_filter.9 \
DRIVER_MODULE.9 \
EVENTHANDLER.9 \
extattr.9 \
+ fail.9 \
fetch.9 \
firmware.9 \
g_access.9 \
Added: head/share/man/man9/fail.9
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/share/man/man9/fail.9 Wed May 27 16:36:54 2009 (r192908)
@@ -0,0 +1,197 @@
+.\"
+.\" Copyright (c) 2009 Isilon Inc 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(s), this list of conditions and the following disclaimer as
+.\" the first lines of this file unmodified other than the possible
+.\" addition of one or more copyright notices.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd May 10, 2009
+.Dt FAIL 9
+.Os
+.Sh NAME
+.Nm KFAIL_POINT_CODE ,
+.Nm KFAIL_POINT_RETURN ,
+.Nm KFAIL_POINT_RETURN_VOID ,
+.Nm KFAIL_POINT_ERROR ,
+.Nm KFAIL_POINT_GOTO ,
+.Nm fail_point ,
+.Nm DEBUG_FP
+.
+.Nd fail points
+.Sh SYNOPSIS
+.In sys/fail.h
+.Fn KFAIL_POINT_CODE "parent" "name" "code"
+.Fn KFAIL_POINT_RETURN "parent" "name"
+.Fn KFAIL_POINT_RETURN_VOID "parent" "name"
+.Fn KFAIL_POINT_ERROR "parent" "name" "error_var"
+.Fn KFAIL_POINT_GOTO "parent" "name" "error_var" "label"
+.Sh DESCRIPTION
+Fail points are used to add code points where errors may be injected
+in a user controlled fashion. Fail points provide a convenient wrapper
+around user provided error injection code, providing a
+.Xr sysctl 9 MIB , and a parser for that MIB that describes how the error
+injection code should fire.
+.Pp
+The base fail point macro is
+.Fn KFAIL_POINT_CODE
+where
+.Fa parent
+is a sysctl tree (frequently
+.Sy DEBUG_FP
+for kernel fail points, but various subsystems may wish to provide
+their own fail point trees), and
+.Fa name
+is the name of the MIB in that tree, and
+.Fa code
+is the error injection code. The
+.Fa code
+argument does not require braces, but it is considered good style to
+use braces for any multi-line code arguments. Inside the
+.Fa code
+argument, the evaluation of
+.Sy RETURN_VALUE
+is derived from the
+.Fn return
+value set in the sysctl MIB. See
+.Sx SYSCTL SETTINGS
+below.
+.Pp
+The remaining
+.Fn KFAIL_POINT_*
+macros are wrappers around common error injection paths:
+.Bl -tag -width 8
+.It Fn KFAIL_POINT_RETURN parent name
+is the equivalent of
+.Sy KFAIL_POINT_CODE(..., return RETURN_VALUE)
+.It Fn KFAIL_POINT_RETURN_VOID parent name
+is the equivalent of
+.Sy KFAIL_POINT_CODE(..., return)
+.It Fn KFAIL_POINT_ERROR parent name error_var
+is the equivalent of
+.Sy KFAIL_POINT_CODE(..., error_var = RETURN_VALUE)
+.It Fn KFAIL_POINT_GOTO parent name error_var label
+is the equivalent of
+.Sy KFAIL_POINT_CODE(...,
+ { error_var = RETURN_VALUE; goto label;})
+.El
+.Pp
+.Sh SYSCTL VARIABLES
+The
+.Fn KFAIL_POINT_*
+macros add sysctl MIBs where specified. Many base kernel MIBs can be
+found in the
+.Sy debug.fail_point
+tree (referenced in code by
+.Sy DEBUG_FP
+).
+.Pp
+The sysctl setting recognizes the following grammar:
+.Pp
+ <fail_point> ::
+ <term> ( "->" <term> )*
+.Pp
+ <term> ::
+ ( (<float> "%") | (<integer> "*" ) )*
+ <type>
+ [ "(" <integer> ")" ]
+.Pp
+ <float> ::
+ <integer> [ "." <integer> ] |
+ "." <integer>
+.Pp
+ <type> ::
+ "off" | "return" | "sleep" | "panic" | "break" | "print"
+.Pp
+The <type>
+argument specifies which action to take:
+.Bl -tag -width ".Dv return"
+.It Sy off
+Take no action (does not trigger fail point code)
+.It Sy return
+Trigger fail point code with specified argument
+.It Sy sleep
+Sleep the specified number of milliseconds
+.It Sy panic
+Panic
+.It Sy break
+Break into the debugger.
+.It Sy print
+Print that the fail point executed
+.El
+.Pp
+The <float>% and <integer>* modifiers prior to <type> control when
+<type> is executed. The <float>% form (e.g. "1.2%") can be used to
+specify a probability that <type> will execute. The <integer>* form
+(e.g. "5*") can be used to specify the number of times <type> should
+be executed before this <term> is disabled. Only the last probability
+and the last count are used if multiple are specified, i.e. "1.2%2%"
+is the same as "2%". When both a probability and a count are
+specified, the probability is evaluated before the count, i.e. "2%5*"
+means "2% of the time, but only execute it 5 times total".
+.Pp
+The operator -> can be used to express cascading terms. If you specify
+<term1>-><term2>, it means that if <term1> doesn't 'execute', <term2>
+is evaluated. For the purpose of this operator, the return() and
+print() operators are the only types that cascade. A return() term
+only cascades if the code executes, and a print() term only cascades
+when passed a non-zero argument.
+.Pp
+.Sh EXAMPLES
+.Bl -tag
+.It Sy sysctl debug.fail_point.foobar="2.1%return(5)"
+21/1000ths of the time, execute
+.Fa code
+with RETURN_VALUE set to 5.
+.It Sy sysctl debug.fail_point.foobar="2%return(5)->5%return(22)"
+2/100th of the time, execute
+.Fa code
+with RETURN_VALUE set to 5. If that doesn't happen, 5% of the time
+execute
+.Fa code
+with RETURN_VALUE set to 22.
+.It Sy sysctl debug.fail_point.foobar="5*return(5)->0.1%return(22)"
+For 5 times, return 5. After that, 1/1000ths of the time, return 22.
+.It Sy sysctl debug.fail_point.foobar="0.1%5*return(5)"
+Return 5 for 1 in 1000 executions, but only execute 5 times total.
+.It Sy sysctl debug.fail_point.foobar="1%*sleep(50)"
+1/100ths of the time, sleep 50ms.
+.El
+.Pp
+.Sh CAVEATS
+It's easy to shoot yourself in the foot by setting fail points too
+aggressively or setting too many in combination. For example, forcing
+.Fn malloc
+to fail consistently is potentially harmful to uptime.
+.Pp
+The
+.Fn sleep
+sysctl setting may not be appropriate in all situations. Currently,
+.Fn fail_point_eval
+does not verify whether the context is appropriate for calling
+.Fn msleep .
+.Pp
+.Sh AUTHORS
+.An -nosplit
+This manual page was written by
+.An Zach Loafman Aq zml at FreeBSD.org .
Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files Wed May 27 16:34:08 2009 (r192907)
+++ head/sys/conf/files Wed May 27 16:36:54 2009 (r192908)
@@ -1860,6 +1860,7 @@ kern/kern_environment.c standard
kern/kern_event.c standard
kern/kern_exec.c standard
kern/kern_exit.c standard
+kern/kern_fail.c standard
kern/kern_fork.c standard
kern/kern_idle.c standard
kern/kern_intr.c standard
Added: head/sys/kern/kern_fail.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/kern/kern_fail.c Wed May 27 16:36:54 2009 (r192908)
@@ -0,0 +1,575 @@
+/*-
+ * Copyright (c) 2009 Isilon Inc 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.
+ */
+/**
+ * @file
+ *
+ * fail(9) Facility.
+ *
+ * @ingroup failpoint_private
+ */
+/**
+ * @defgroup failpoint fail(9) Facility
+ *
+ * Failpoints allow for injecting fake errors into running code on the fly,
+ * without modifying code or recompiling with flags. Failpoints are always
+ * present, and are very efficient when disabled. Failpoints are described
+ * in man fail(9).
+ */
+/**
+ * @defgroup failpoint_private Private fail(9) Implementation functions
+ *
+ * Private implementations for the actual failpoint code.
+ *
+ * @ingroup failpoint
+ */
+/**
+ * @addtogroup failpoint_private
+ * @{
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/errno.h>
+#include <sys/fail.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/sbuf.h>
+
+#include <machine/stdarg.h>
+
+#ifdef ILOG_DEFINE_FOR_FILE
+ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point);
+#endif
+
+MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system");
+#define fp_free(ptr) free(ptr, M_FAIL_POINT)
+#define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags))
+
+static struct mtx g_fp_mtx;
+MTX_SYSINIT(g_fp_mtx, &g_fp_mtx, "fail point mtx", MTX_DEF);
+#define FP_LOCK() mtx_lock(&g_fp_mtx)
+#define FP_UNLOCK() mtx_unlock(&g_fp_mtx)
+
+static inline void
+fail_point_sleep(struct fail_point *fp, struct fail_point_entry *ent,
+ int msecs, enum fail_point_return_code *pret)
+{
+ /* convert from millisecs to ticks, rounding up */
+ int timo = ((msecs * hz) + 999) / 1000;
+
+ if (timo) {
+ if (fp->fp_sleep_fn == NULL) {
+ msleep(fp, &g_fp_mtx, PWAIT, "failpt", timo);
+ } else {
+ timeout(fp->fp_sleep_fn, fp->fp_sleep_arg, timo);
+ *pret = FAIL_POINT_RC_QUEUED;
+ }
+ }
+}
+
+
+/**
+ * Defines stating the equivalent of probablilty one (100%)
+ */
+enum {
+ PROB_MAX = 1000000, /* probability between zero and this number */
+ PROB_DIGITS = 6, /* number of zero's in above number */
+};
+
+static const char *fail_type_strings[] = {
+ "off",
+ "panic",
+ "return",
+ "break",
+ "print",
+ "sleep",
+};
+
+static char *parse_fail_point(struct fail_point_entries *, char *);
+static char *parse_term(struct fail_point_entries *, char *);
+static char *parse_number(int *out_units, int *out_decimal, char *);
+static char *parse_type(struct fail_point_entry *, char *);
+static void free_entry(struct fail_point_entries *, struct fail_point_entry *);
+static void clear_entries(struct fail_point_entries *);
+
+/**
+ * Initialize a fail_point. The name is formed in a printf-like fashion
+ * from "fmt" and subsequent arguments. This function is generally used
+ * for custom failpoints located at odd places in the sysctl tree, and is
+ * not explicitly needed for standard in-line-declared failpoints.
+ *
+ * @ingroup failpoint
+ */
+void
+fail_point_init(struct fail_point *fp, const char *fmt, ...)
+{
+ va_list ap;
+ char *name;
+ int n;
+
+ TAILQ_INIT(&fp->fp_entries);
+ fp->fp_flags = 0;
+
+ /* Figure out the size of the name. */
+ va_start(ap, fmt);
+ n = vsnprintf(NULL, 0, fmt, ap);
+ va_end(ap);
+
+ /* Allocate the name and fill it in. */
+ name = fp_malloc(n + 1, M_WAITOK);
+ if (name != NULL) {
+ va_start(ap, fmt);
+ vsnprintf(name, n + 1, fmt, ap);
+ va_end(ap);
+ }
+ fp->fp_name = name;
+ fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
+ fp->fp_sleep_fn = NULL;
+ fp->fp_sleep_arg = NULL;
+}
+
+/**
+ * Free the resources held by a fail_point.
+ *
+ * @ingroup failpoint
+ */
+void
+fail_point_destroy(struct fail_point *fp)
+{
+ struct fail_point_entry *ent;
+
+ if (fp->fp_flags & FAIL_POINT_DYNAMIC_NAME && fp->fp_name != NULL) {
+ fp_free((void *)(intptr_t)fp->fp_name);
+ fp->fp_name = NULL;
+ }
+ fp->fp_flags = 0;
+
+ while (!TAILQ_EMPTY(&fp->fp_entries)) {
+ ent = TAILQ_FIRST(&fp->fp_entries);
+ TAILQ_REMOVE(&fp->fp_entries, ent, fe_entries);
+ fp_free(ent);
+ }
+}
+
+/**
+ * This does the real work of evaluating a fail point. If the fail point tells
+ * us to return a value, this function returns 1 and fills in 'return_value'
+ * (return_value is allowed to be null). If the fail point tells us to panic,
+ * we never return. Otherwise we just return 0 after doing some work, which
+ * means "keep going".
+ */
+enum fail_point_return_code
+fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
+{
+ enum fail_point_return_code ret = FAIL_POINT_RC_CONTINUE;
+ struct fail_point_entry *ent, *next;
+ int msecs;
+
+ FP_LOCK();
+
+ ent = TAILQ_FIRST(&fp->fp_entries);
+ while (ent) {
+ int cont = 0; /* don't continue by default */
+ next = TAILQ_NEXT(ent, fe_entries);
+
+ if (ent->fe_prob < PROB_MAX &&
+ ent->fe_prob < random() % PROB_MAX) {
+ cont = 1;
+ goto loop_end;
+ }
+
+ switch (ent->fe_type) {
+ case FAIL_POINT_PANIC:
+ panic("fail point %s panicking", fp->fp_name);
+ /* NOTREACHED */
+
+ case FAIL_POINT_RETURN:
+ if (return_value)
+ *return_value = ent->fe_arg;
+ ret = FAIL_POINT_RC_RETURN;
+ break;
+
+ case FAIL_POINT_BREAK:
+ printf("fail point %s breaking to debugger\n", fp->fp_name);
+ breakpoint();
+ break;
+
+ case FAIL_POINT_PRINT:
+ printf("fail point %s executing\n", fp->fp_name);
+ cont = ent->fe_arg;
+ break;
+
+ case FAIL_POINT_SLEEP:
+ /*
+ * Free the entry now if necessary, since
+ * we're about to drop the mutex and sleep.
+ */
+ msecs = ent->fe_arg;
+ if (ent->fe_count > 0 && --ent->fe_count == 0) {
+ free_entry(&fp->fp_entries, ent);
+ ent = NULL;
+ }
+
+ if (msecs)
+ fail_point_sleep(fp, ent, msecs, &ret);
+ break;
+
+ default:
+ break;
+ }
+
+ if (ent && ent->fe_count > 0 && --ent->fe_count == 0)
+ free_entry(&fp->fp_entries, ent);
+
+loop_end:
+ if (cont)
+ ent = next;
+ else
+ break;
+ }
+
+ /* Get rid of "off"s at the end. */
+ while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
+ ent->fe_type == FAIL_POINT_OFF)
+ free_entry(&fp->fp_entries, ent);
+
+ FP_UNLOCK();
+
+ return ret;
+}
+
+/**
+ * Translate internal fail_point structure into human-readable text.
+ */
+static void
+fail_point_get(struct fail_point *fp, struct sbuf *sb)
+{
+ struct fail_point_entry *ent;
+
+ FP_LOCK();
+
+ TAILQ_FOREACH(ent, &fp->fp_entries, fe_entries) {
+ if (ent->fe_prob < PROB_MAX) {
+ int decimal = ent->fe_prob % (PROB_MAX / 100);
+ int units = ent->fe_prob / (PROB_MAX / 100);
+ sbuf_printf(sb, "%d", units);
+ if (decimal) {
+ int digits = PROB_DIGITS - 2;
+ while (!(decimal % 10)) {
+ digits--;
+ decimal /= 10;
+ }
+ sbuf_printf(sb, ".%0*d", digits, decimal);
+ }
+ sbuf_printf(sb, "%%");
+ }
+ if (ent->fe_count > 0)
+ sbuf_printf(sb, "%d*", ent->fe_count);
+ sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type]);
+ if (ent->fe_arg)
+ sbuf_printf(sb, "(%d)", ent->fe_arg);
+ if (TAILQ_NEXT(ent, fe_entries))
+ sbuf_printf(sb, "->");
+ }
+ if (TAILQ_EMPTY(&fp->fp_entries))
+ sbuf_printf(sb, "off");
+
+ FP_UNLOCK();
+}
+
+/**
+ * Set an internal fail_point structure from a human-readable failpoint string
+ * in a lock-safe manner.
+ */
+static int
+fail_point_set(struct fail_point *fp, char *buf)
+{
+ int error = 0;
+ struct fail_point_entry *ent, *ent_next;
+ struct fail_point_entries new_entries;
+
+ /* Parse new entries. */
+ TAILQ_INIT(&new_entries);
+ if (!parse_fail_point(&new_entries, buf)) {
+ clear_entries(&new_entries);
+ error = EINVAL;
+ goto end;
+ }
+
+ FP_LOCK();
+
+ /* Move new entries in. */
+ TAILQ_SWAP(&fp->fp_entries, &new_entries, fail_point_entry, fe_entries);
+ clear_entries(&new_entries);
+
+ /* Get rid of useless zero probability entries. */
+ TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, ent_next) {
+ if (ent->fe_prob == 0)
+ free_entry(&fp->fp_entries, ent);
+ }
+
+ /* Get rid of "off"s at the end. */
+ while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
+ ent->fe_type == FAIL_POINT_OFF)
+ free_entry(&fp->fp_entries, ent);
+
+ FP_UNLOCK();
+
+ end:
+#ifdef IWARNING
+ if (error)
+ IWARNING("Failed to set %s (%s) to %s",
+ fp->fp_name, fp->fp_location, buf);
+ else
+ INOTICE("Set %s (%s) to %s",
+ fp->fp_name, fp->fp_location, buf);
+#endif /* IWARNING */
+
+ return error;
+}
+
+#define MAX_FAIL_POINT_BUF 1023
+
+/**
+ * Handle kernel failpoint set/get.
+ */
+int
+fail_point_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ struct fail_point *fp = arg1;
+ char *buf = NULL;
+ struct sbuf sb;
+ int error;
+
+ /* Retrieving */
+ sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
+ fail_point_get(fp, &sb);
+ sbuf_trim(&sb);
+ sbuf_finish(&sb);
+ error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
+ sbuf_delete(&sb);
+
+ /* Setting */
+ if (!error && req->newptr) {
+ if (req->newlen > MAX_FAIL_POINT_BUF) {
+ error = EINVAL;
+ goto out;
+ }
+
+ buf = fp_malloc(req->newlen + 1, M_WAITOK);
+
+ error = SYSCTL_IN(req, buf, req->newlen);
+ if (error)
+ goto out;
+ buf[req->newlen] = '\0';
+
+ error = fail_point_set(fp, buf);
+ }
+
+out:
+ if (buf)
+ fp_free(buf);
+ return error;
+}
+
+/**
+ * Internal helper function to translate a human-readable failpoint string
+ * into a internally-parsable fail_point structure.
+ */
+static char *
+parse_fail_point(struct fail_point_entries *ents, char *p)
+{
+ /* <fail_point> ::
+ * <term> ( "->" <term> )*
+ */
+ if (!(p = parse_term(ents, p)))
+ return 0;
+ while (*p)
+ if (p[0] != '-' || p[1] != '>' || !(p = parse_term(ents, p+2)))
+ return 0;
+ return p;
+}
+
+/**
+ * Internal helper function to parse an individual term from a failpoint.
+ */
+static char *
+parse_term(struct fail_point_entries *ents, char *p)
+{
+ struct fail_point_entry *ent;
+
+ ent = fp_malloc(sizeof *ent, M_WAITOK | M_ZERO);
+ ent->fe_prob = PROB_MAX;
+ TAILQ_INSERT_TAIL(ents, ent, fe_entries);
+
+ /*
+ * <term> ::
+ * ( (<float> "%") | (<integer> "*" ) )*
+ * <type>
+ * [ "(" <integer> ")" ]
+ */
+
+ /* ( (<float> "%") | (<integer> "*" ) )* */
+ while (('0' <= *p && *p <= '9') || *p == '.') {
+ int units, decimal;
+
+ if (!(p = parse_number(&units, &decimal, p)))
+ return 0;
+
+ if (*p == '%') {
+ if (units > 100) /* prevent overflow early */
+ units = 100;
+ ent->fe_prob = units * (PROB_MAX / 100) + decimal;
+ if (ent->fe_prob > PROB_MAX)
+ ent->fe_prob = PROB_MAX;
+
+ } else if (*p == '*') {
+ if (!units || decimal)
+ return 0;
+ ent->fe_count = units;;
+
+ } else {
+ return 0;
+ }
+
+ p++;
+ }
+
+ /* <type> */
+ if (!(p = parse_type(ent, p)))
+ return 0;
+ if (*p == '\0')
+ return p;
+
+ /* [ "(" <integer> ")" ] */
+ if (*p != '(')
+ return p;
+ p++;
+ if (('0' <= *p && *p <= '9') || *p == '-')
+ ent->fe_arg = strtol(p, &p, 0);
+ else
+ return 0;
+ if (*p++ != ')')
+ return 0;
+
+ 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 0;
+
+ /* fractional part */
+ *out_decimal = 0;
+ if (*p == '.') {
+ int digits = 0;
+ p++;
+ while ('0' <= *p && *p <= '9') {
+ 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 0;
+ 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;
+ char *end = beg;
+ while ('a' <= *end && *end <= 'z')
+ end++;
+ if (beg == end)
+ return 0;
+ for (type = FAIL_POINT_OFF; type != FAIL_POINT_INVALID; type++) {
+ const char *p = fail_type_strings[type];
+ const char *q = beg;
+ while (q < end && *p++ == *q++);
+ if (q == end && *p == '\0') {
+ ent->fe_type = type;
+ return end;
+ }
+ }
+ return 0;
+}
+
+/**
+ * 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");
Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c Wed May 27 16:34:08 2009 (r192907)
+++ head/sys/kern/vfs_bio.c Wed May 27 16:36:54 2009 (r192908)
@@ -48,6 +48,7 @@ __FBSDID("$FreeBSD$");
#include <sys/buf.h>
#include <sys/devicestat.h>
#include <sys/eventhandler.h>
+#include <sys/fail.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
@@ -1167,6 +1168,15 @@ buf_dirty_count_severe(void)
return(numdirtybuffers >= hidirtybuffers);
}
+static __noinline int
+buf_vm_page_count_severe(void)
+{
+
+ KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
+
+ return vm_page_count_severe();
+}
+
/*
* brelse:
*
@@ -1233,7 +1243,7 @@ brelse(struct buf *bp)
*/
if (bp->b_flags & B_DELWRI)
bp->b_flags &= ~B_RELBUF;
- else if (vm_page_count_severe()) {
+ else if (buf_vm_page_count_severe()) {
/*
* The locking of the BO_LOCK is not necessary since
* BKGRDINPROG cannot be set while we hold the buf
@@ -1502,7 +1512,7 @@ bqrelse(struct buf *bp)
* lock, it can only be cleared if it is already
* pending.
*/
- if (!vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
+ if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
bp->b_qindex = QUEUE_CLEAN;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
b_freelist);
@@ -1571,7 +1581,7 @@ vfs_vmio_release(struct buf *bp)
vm_page_free(m);
} else if (bp->b_flags & B_DIRECT) {
vm_page_try_to_free(m);
- } else if (vm_page_count_severe()) {
+ } else if (buf_vm_page_count_severe()) {
vm_page_try_to_cache(m);
}
}
Added: head/sys/sys/fail.h
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/sys/fail.h Wed May 27 16:36:54 2009 (r192908)
@@ -0,0 +1,260 @@
+/*-
+ * Copyright (c) 2009 Isilon Inc 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/types.h>
+
+#include <sys/linker_set.h>
+#include <sys/param.h>
+#include <sys/queue.h>
+#include <sys/sysctl.h>
+
+
+/**
+ * Failpoint types.
+ * Don't change these without changing fail_type_strings in fail.c.
+ * @ingroup failpoint_private
+ */
+enum fail_point_t {
+ FAIL_POINT_OFF, /**< don't fail */
+ FAIL_POINT_PANIC, /**< panic */
+ FAIL_POINT_RETURN, /**< return an errorcode */
+ FAIL_POINT_BREAK, /**< break into the debugger */
+ FAIL_POINT_PRINT, /**< print a message */
+ FAIL_POINT_SLEEP, /**< sleep for some msecs */
+ FAIL_POINT_INVALID, /**< placeholder */
+};
+
+/**
+ * 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 */
+};
+
+TAILQ_HEAD(fail_point_entries, fail_point_entry);
+/**
+ * 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 */
+ struct fail_point_entries fp_entries; /**< list of entries */
+ int fp_flags;
+ void (*fp_sleep_fn)(void *); /**< Function to call at end of
+ * sleep for sleep failpoints */
+ void *fp_sleep_arg; /**< Arg for sleep_fn */
+};
+
+#define FAIL_POINT_DYNAMIC_NAME 0x01 /**< Must free name on destroy */
+
+/**
+ * Internal structure tracking a single term of a complete failpoint.
+ * @ingroup failpoint_private
+ */
+struct fail_point_entry {
+ enum fail_point_t fe_type; /**< type of entry */
+ int fe_arg; /**< argument to type (e.g. return value) */
+ int fe_prob; /**< likelihood of firing in millionths */
+ int fe_count; /**< number of times to fire, 0 means always */
+
+ TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */
+};
+
+/* 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);
+
+/**
+ * Set the sleep function for a fail point
+ * If sleep_fn is specified, then FAIL_POINT_SLEEP will result in a
+ * (*fp->sleep_fn)(fp->sleep_arg) call by the timer thread. Otherwise,
+ * if sleep_fn is NULL (default), then FAIL_POINT_SLEEP will result in the
+ * fail_point_eval() call sleeping.
+ */
+static __inline void
+fail_point_sleep_set_func(struct fail_point *fp, void (*sleep_fn)(void *))
+{
+ fp->fp_sleep_fn = sleep_fn;
+}
+
+/**
+ * Set the argument for the sleep function for a fail point
+ */
+static __inline void
+fail_point_sleep_set_arg(struct fail_point *fp, void *sleep_arg)
+{
+ fp->fp_sleep_arg = sleep_arg;
+}
+
+/**
+ * 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
*** DIFF OUTPUT TRUNCATED AT 1000 LINES ***
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