freebsd-dev/sys/kern/subr_turnstile.c
John Baldwin 606f8eb27a Remove the mtx_t, witness_t, and witness_blessed_t types. Instead, just
use struct mtx, struct witness, and struct witness_blessed.

Requested by:	bde
2000-09-14 20:15:16 +00:00

799 lines
19 KiB
C

/*-
* Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
*
* 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.
* 3. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
*
* from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
* $FreeBSD$
*/
/*
* Main Entry: witness
* Pronunciation: 'wit-n&s
* Function: noun
* Etymology: Middle English witnesse, from Old English witnes knowledge,
* testimony, witness, from 2wit
* Date: before 12th century
* 1 : attestation of a fact or event : TESTIMONY
* 2 : one that gives evidence; specifically : one who testifies in
* a cause or before a judicial tribunal
* 3 : one asked to be present at a transaction so as to be able to
* testify to its having taken place
* 4 : one who has personal knowledge of something
* 5 a : something serving as evidence or proof : SIGN
* b : public affirmation by word or example of usually
* religious faith or conviction <the heroic witness to divine
* life -- Pilot>
* 6 capitalized : a member of the Jehovah's Witnesses
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/ktr.h>
#include <machine/cpu.h>
#define _KERN_MUTEX_C_ /* Cause non-inlined mtx_*() to be compiled. */
#include <machine/mutex.h>
/*
* The non-inlined versions of the mtx_*() functions are always built (above),
* but the witness code depends on the SMP_DEBUG and WITNESS kernel options
* being specified.
*/
#if (defined(SMP_DEBUG) && defined(WITNESS))
#define WITNESS_COUNT 200
#define WITNESS_NCHILDREN 2
#ifndef WITNESS
#define WITNESS 0 /* default off */
#endif
#ifndef SMP
extern int witness_spin_check;
#endif
int witness_watch;
struct witness {
struct witness *w_next;
char *w_description;
const char *w_file;
int w_line;
struct witness *w_morechildren;
u_char w_childcnt;
u_char w_Giant_squawked:1;
u_char w_other_squawked:1;
u_char w_same_squawked:1;
u_char w_sleep:1;
u_char w_spin:1; /* this is a spin mutex */
u_int w_level;
struct witness *w_children[WITNESS_NCHILDREN];
};
struct witness_blessed {
char *b_lock1;
char *b_lock2;
};
#ifdef KDEBUG
/*
* When WITNESS_KDEBUG is set to 1, it will cause the system to
* drop into kdebug() when:
* - a lock heirarchy violation occurs
* - locks are held when going to sleep.
*/
#ifndef WITNESS_KDEBUG
#define WITNESS_KDEBUG 0
#endif
int witness_kdebug = WITNESS_KDEBUG;
#endif /* KDEBUG */
#ifndef WITNESS_SKIPSPIN
#define WITNESS_SKIPSPIN 0
#endif
int witness_skipspin = WITNESS_SKIPSPIN;
static struct mtx w_mtx;
static struct witness *w_free;
static struct witness *w_all;
static int w_inited;
static int witness_dead; /* fatal error, probably no memory */
static struct witness w_data[WITNESS_COUNT];
static struct witness *enroll __P((char *description, int flag));
static int itismychild __P((struct witness *parent, struct witness *child));
static void removechild __P((struct witness *parent, struct witness *child));
static int isitmychild __P((struct witness *parent, struct witness *child));
static int isitmydescendant __P((struct witness *parent, struct witness *child));
static int dup_ok __P((struct witness *));
static int blessed __P((struct witness *, struct witness *));
static void witness_displaydescendants
__P((void(*)(const char *fmt, ...), struct witness *));
static void witness_leveldescendents __P((struct witness *parent, int level));
static void witness_levelall __P((void));
static struct witness * witness_get __P((void));
static void witness_free __P((struct witness *m));
static char *ignore_list[] = {
"witness lock",
"Kdebug", /* breaks rules and may or may not work */
"Page Alias", /* sparc only, witness lock won't block intr */
NULL
};
static char *spin_order_list[] = {
"sched lock",
"log mtx",
"zslock", /* sparc only above log, this one is a real hack */
"time lock", /* above callout */
"callout mtx", /* above wayout */
/*
* leaf locks
*/
"wayout mtx",
"kernel_pmap", /* sparc only, logically equal "pmap" below */
"pmap", /* sparc only */
NULL
};
static char *order_list[] = {
"tcb", "inp", "so_snd", "so_rcv", "Giant lock", NULL,
"udb", "inp", NULL,
"unp head", "unp", "so_snd", NULL,
"de0", "Giant lock", NULL,
"ifnet", "Giant lock", NULL,
"fifo", "so_snd", NULL,
"hme0", "Giant lock", NULL,
"esp0", "Giant lock", NULL,
"hfa0", "Giant lock", NULL,
"so_rcv", "atm_global", NULL,
"so_snd", "atm_global", NULL,
"NFS", "Giant lock", NULL,
NULL
};
static char *dup_list[] = {
"inp",
"process group",
"session",
"unp",
"rtentry",
"rawcb",
NULL
};
static char *sleep_list[] = {
"Giant lock",
NULL
};
/*
* Pairs of locks which have been blessed
* Don't complain about order problems with blessed locks
*/
static struct witness_blessed blessed_list[] = {
};
static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed);
void
witness_init(struct mtx *m, int flag)
{
m->mtx_witness = enroll(m->mtx_description, flag);
}
void
witness_destroy(struct mtx *m)
{
struct mtx *m1;
struct proc *p;
p = CURPROC;
for ((m1 = LIST_FIRST(&p->p_heldmtx)); m1 != NULL;
m1 = LIST_NEXT(m1, mtx_held)) {
if (m1 == m) {
LIST_REMOVE(m, mtx_held);
break;
}
}
return;
}
void
witness_enter(struct mtx *m, int flags, const char *file, int line)
{
struct witness *w, *w1;
struct mtx *m1;
struct proc *p;
int i;
#ifdef KDEBUG
int go_into_kdebug = 0;
#endif /* KDEBUG */
w = m->mtx_witness;
p = CURPROC;
if (flags & MTX_SPIN) {
if (!w->w_spin)
panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @"
" %s:%d", m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
mtx_enter(&w_mtx, MTX_SPIN);
i = witness_spin_check;
if (i != 0 && w->w_level < i) {
mtx_exit(&w_mtx, MTX_SPIN);
panic("mutex_enter(%s:%x, MTX_SPIN) out of order @"
" %s:%d already holding %s:%x",
m->mtx_description, w->w_level, file, line,
spin_order_list[ffs(i)-1], i);
}
PCPU_SET(witness_spin_check, i | w->w_level);
mtx_exit(&w_mtx, MTX_SPIN);
return;
}
if (w->w_spin)
panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d",
m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
if (witness_dead)
goto out;
if (cold)
goto out;
if (!mtx_legal2block())
panic("blockable mtx_enter() of %s when not legal @ %s:%d",
m->mtx_description, file, line);
/*
* Is this the first mutex acquired
*/
if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL)
goto out;
if ((w1 = m1->mtx_witness) == w) {
if (w->w_same_squawked || dup_ok(w))
goto out;
w->w_same_squawked = 1;
printf("acquring duplicate lock of same type: \"%s\"\n",
m->mtx_description);
printf(" 1st @ %s:%d\n", w->w_file, w->w_line);
printf(" 2nd @ %s:%d\n", file, line);
#ifdef KDEBUG
go_into_kdebug = 1;
#endif /* KDEBUG */
goto out;
}
MPASS(!mtx_owned(&w_mtx));
mtx_enter(&w_mtx, MTX_SPIN);
/*
* If we have a known higher number just say ok
*/
if (witness_watch > 1 && w->w_level > w1->w_level) {
mtx_exit(&w_mtx, MTX_SPIN);
goto out;
}
if (isitmydescendant(m1->mtx_witness, w)) {
mtx_exit(&w_mtx, MTX_SPIN);
goto out;
}
for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) {
ASS(i < 200);
w1 = m1->mtx_witness;
if (isitmydescendant(w, w1)) {
mtx_exit(&w_mtx, MTX_SPIN);
if (blessed(w, w1))
goto out;
if (m1 == &Giant) {
if (w1->w_Giant_squawked)
goto out;
else
w1->w_Giant_squawked = 1;
} else {
if (w1->w_other_squawked)
goto out;
else
w1->w_other_squawked = 1;
}
printf("lock order reversal\n");
printf(" 1st %s last acquired @ %s:%d\n",
w->w_description, w->w_file, w->w_line);
printf(" 2nd %p %s @ %s:%d\n",
m1, w1->w_description, w1->w_file, w1->w_line);
printf(" 3rd %p %s @ %s:%d\n",
m, w->w_description, file, line);
#ifdef KDEBUG
go_into_kdebug = 1;
#endif /* KDEBUG */
goto out;
}
}
m1 = LIST_FIRST(&p->p_heldmtx);
if (!itismychild(m1->mtx_witness, w))
mtx_exit(&w_mtx, MTX_SPIN);
out:
#ifdef KDEBUG
if (witness_kdebug && go_into_kdebug)
kdebug();
#endif /* KDEBUG */
w->w_file = file;
w->w_line = line;
m->mtx_line = line;
m->mtx_file = file;
/*
* If this pays off it likely means that a mutex being witnessed
* is acquired in hardclock. Put it in the ignore list. It is
* likely not the mutex this assert fails on.
*/
ASS(m->mtx_held.le_prev == NULL);
LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held);
}
void
witness_exit(struct mtx *m, int flags, const char *file, int line)
{
struct witness *w;
w = m->mtx_witness;
if (flags & MTX_SPIN) {
if (!w->w_spin)
panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @"
" %s:%d", m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
mtx_enter(&w_mtx, MTX_SPIN);
PCPU_SET(witness_spin_check, witness_spin_check & ~w->w_level);
mtx_exit(&w_mtx, MTX_SPIN);
return;
}
if (w->w_spin)
panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d",
m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold)
panic("switchable mtx_exit() of %s when not legal @ %s:%d",
m->mtx_description, file, line);
LIST_REMOVE(m, mtx_held);
m->mtx_held.le_prev = NULL;
}
void
witness_try_enter(struct mtx *m, int flags, const char *file, int line)
{
struct proc *p;
struct witness *w = m->mtx_witness;
if (flags & MTX_SPIN) {
if (!w->w_spin)
panic("mutex_try_enter: "
"MTX_SPIN on MTX_DEF mutex %s @ %s:%d",
m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
mtx_enter(&w_mtx, MTX_SPIN);
PCPU_SET(witness_spin_check, witness_spin_check | w->w_level);
mtx_exit(&w_mtx, MTX_SPIN);
return;
}
if (w->w_spin)
panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d",
m->mtx_description, file, line);
if (m->mtx_recurse != 0)
return;
w->w_file = file;
w->w_line = line;
m->mtx_line = line;
m->mtx_file = file;
p = CURPROC;
ASS(m->mtx_held.le_prev == NULL);
LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held);
}
void
witness_display(void(*prnt)(const char *fmt, ...))
{
struct witness *w, *w1;
witness_levelall();
for (w = w_all; w; w = w->w_next) {
if (w->w_file == NULL)
continue;
for (w1 = w_all; w1; w1 = w1->w_next) {
if (isitmychild(w1, w))
break;
}
if (w1 != NULL)
continue;
/*
* This lock has no anscestors, display its descendants.
*/
witness_displaydescendants(prnt, w);
}
prnt("\nMutex which were never acquired\n");
for (w = w_all; w; w = w->w_next) {
if (w->w_file != NULL)
continue;
prnt("%s\n", w->w_description);
}
}
int
witness_sleep(int check_only, struct mtx *mtx, const char *file, int line)
{
struct mtx *m;
struct proc *p;
char **sleep;
int n = 0;
p = CURPROC;
for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL;
m = LIST_NEXT(m, mtx_held)) {
if (m == mtx)
continue;
for (sleep = sleep_list; *sleep!= NULL; sleep++)
if (strcmp(m->mtx_description, *sleep) == 0)
goto next;
printf("%s:%d: %s with \"%s\" locked from %s:%d\n",
file, line, check_only ? "could sleep" : "sleeping",
m->mtx_description,
m->mtx_witness->w_file, m->mtx_witness->w_line);
n++;
next:
}
#ifdef KDEBUG
if (witness_kdebug && n)
kdebug();
#endif /* KDEBUG */
return (n);
}
static struct witness *
enroll(char *description, int flag)
{
int i;
struct witness *w, *w1;
char **ignore;
char **order;
if (!witness_watch)
return (NULL);
for (ignore = ignore_list; *ignore != NULL; ignore++)
if (strcmp(description, *ignore) == 0)
return (NULL);
if (w_inited == 0) {
mtx_init(&w_mtx, "witness lock", MTX_DEF);
for (i = 0; i < WITNESS_COUNT; i++) {
w = &w_data[i];
witness_free(w);
}
w_inited = 1;
for (order = order_list; *order != NULL; order++) {
w = enroll(*order, MTX_DEF);
w->w_file = "order list";
for (order++; *order != NULL; order++) {
w1 = enroll(*order, MTX_DEF);
w1->w_file = "order list";
itismychild(w, w1);
w = w1;
}
}
}
if ((flag & MTX_SPIN) && witness_skipspin)
return (NULL);
mtx_enter(&w_mtx, MTX_SPIN);
for (w = w_all; w; w = w->w_next) {
if (strcmp(description, w->w_description) == 0) {
mtx_exit(&w_mtx, MTX_SPIN);
return (w);
}
}
if ((w = witness_get()) == NULL)
return (NULL);
w->w_next = w_all;
w_all = w;
w->w_description = description;
mtx_exit(&w_mtx, MTX_SPIN);
if (flag & MTX_SPIN) {
w->w_spin = 1;
i = 1;
for (order = spin_order_list; *order != NULL; order++) {
if (strcmp(description, *order) == 0)
break;
i <<= 1;
}
if (*order == NULL)
panic("spin lock %s not in order list", description);
w->w_level = i;
}
return (w);
}
static int
itismychild(struct witness *parent, struct witness *child)
{
static int recursed;
/*
* Insert "child" after "parent"
*/
while (parent->w_morechildren)
parent = parent->w_morechildren;
if (parent->w_childcnt == WITNESS_NCHILDREN) {
if ((parent->w_morechildren = witness_get()) == NULL)
return (1);
parent = parent->w_morechildren;
}
ASS(child != NULL);
parent->w_children[parent->w_childcnt++] = child;
/*
* now prune whole tree
*/
if (recursed)
return (0);
recursed = 1;
for (child = w_all; child != NULL; child = child->w_next) {
for (parent = w_all; parent != NULL;
parent = parent->w_next) {
if (!isitmychild(parent, child))
continue;
removechild(parent, child);
if (isitmydescendant(parent, child))
continue;
itismychild(parent, child);
}
}
recursed = 0;
witness_levelall();
return (0);
}
static void
removechild(struct witness *parent, struct witness *child)
{
struct witness *w, *w1;
int i;
for (w = parent; w != NULL; w = w->w_morechildren)
for (i = 0; i < w->w_childcnt; i++)
if (w->w_children[i] == child)
goto found;
return;
found:
for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren)
continue;
w->w_children[i] = w1->w_children[--w1->w_childcnt];
ASS(w->w_children[i] != NULL);
if (w1->w_childcnt != 0)
return;
if (w1 == parent)
return;
for (w = parent; w->w_morechildren != w1; w = w->w_morechildren)
continue;
w->w_morechildren = 0;
witness_free(w1);
}
static int
isitmychild(struct witness *parent, struct witness *child)
{
struct witness *w;
int i;
for (w = parent; w != NULL; w = w->w_morechildren) {
for (i = 0; i < w->w_childcnt; i++) {
if (w->w_children[i] == child)
return (1);
}
}
return (0);
}
static int
isitmydescendant(struct witness *parent, struct witness *child)
{
struct witness *w;
int i;
int j;
for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) {
ASS(j < 1000);
for (i = 0; i < w->w_childcnt; i++) {
if (w->w_children[i] == child)
return (1);
}
for (i = 0; i < w->w_childcnt; i++) {
if (isitmydescendant(w->w_children[i], child))
return (1);
}
}
return (0);
}
void
witness_levelall (void)
{
struct witness *w, *w1;
for (w = w_all; w; w = w->w_next)
if (!w->w_spin)
w->w_level = 0;
for (w = w_all; w; w = w->w_next) {
if (w->w_spin)
continue;
for (w1 = w_all; w1; w1 = w1->w_next) {
if (isitmychild(w1, w))
break;
}
if (w1 != NULL)
continue;
witness_leveldescendents(w, 0);
}
}
static void
witness_leveldescendents(struct witness *parent, int level)
{
int i;
struct witness *w;
if (parent->w_level < level)
parent->w_level = level;
level++;
for (w = parent; w != NULL; w = w->w_morechildren)
for (i = 0; i < w->w_childcnt; i++)
witness_leveldescendents(w->w_children[i], level);
}
static void
witness_displaydescendants(void(*prnt)(const char *fmt, ...),
struct witness *parent)
{
struct witness *w;
int i;
int level = parent->w_level;
prnt("%d", level);
if (level < 10)
prnt(" ");
for (i = 0; i < level; i++)
prnt(" ");
prnt("%s", parent->w_description);
if (parent->w_file != NULL) {
prnt(" -- last acquired @ %s", parent->w_file);
#ifndef W_USE_WHERE
prnt(":%d", parent->w_line);
#endif
prnt("\n");
}
for (w = parent; w != NULL; w = w->w_morechildren)
for (i = 0; i < w->w_childcnt; i++)
witness_displaydescendants(prnt, w->w_children[i]);
}
static int
dup_ok(struct witness *w)
{
char **dup;
for (dup = dup_list; *dup!= NULL; dup++)
if (strcmp(w->w_description, *dup) == 0)
return (1);
return (0);
}
static int
blessed(struct witness *w1, struct witness *w2)
{
int i;
struct witness_blessed *b;
for (i = 0; i < blessed_count; i++) {
b = &blessed_list[i];
if (strcmp(w1->w_description, b->b_lock1) == 0) {
if (strcmp(w2->w_description, b->b_lock2) == 0)
return (1);
continue;
}
if (strcmp(w1->w_description, b->b_lock2) == 0)
if (strcmp(w2->w_description, b->b_lock1) == 0)
return (1);
}
return (0);
}
static struct witness *
witness_get()
{
struct witness *w;
if ((w = w_free) == NULL) {
witness_dead = 1;
mtx_exit(&w_mtx, MTX_SPIN);
printf("witness exhausted\n");
return (NULL);
}
w_free = w->w_next;
bzero(w, sizeof(*w));
return (w);
}
static void
witness_free(struct witness *w)
{
w->w_next = w_free;
w_free = w;
}
void
witness_list(struct proc *p)
{
struct mtx *m;
for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL;
m = LIST_NEXT(m, mtx_held)) {
printf("\t\"%s\" (%p) locked at %s:%d\n",
m->mtx_description, m,
m->mtx_witness->w_file, m->mtx_witness->w_line);
}
}
void
witness_save(struct mtx *m, const char **filep, int *linep)
{
*filep = m->mtx_witness->w_file;
*linep = m->mtx_witness->w_line;
}
void
witness_restore(struct mtx *m, const char *file, int line)
{
m->mtx_witness->w_file = file;
m->mtx_witness->w_line = line;
}
#endif /* (defined(SMP_DEBUG) && defined(WITNESS)) */