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freebsd-nq/sys/kern/subr_witness.c
Jeff Roberson f22a4b62f5 Add a new mtx_init option "MTX_DUPOK" which allows duplicate acquires of locks 
with this flag.  Remove the dup_list and dup_ok code from subr_witness.  Now
we just check for the flag instead of doing string compares.

Also, switch the process lock, process group lock, and uma per cpu locks over
to this interface.  The original mechanism did not work well for uma because
per cpu lock names are unique to each zone.

Approved by:	jhb
2002-03-27 09:23:41 +00:00

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/*-
* 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 $
* and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
* $FreeBSD$
*/
/*
* Implementation of the `witness' lock verifier. Originally implemented for
* mutexes in BSD/OS. Extended to handle generic lock objects and lock
* classes in 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 "opt_ddb.h"
#include "opt_witness.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <ddb/ddb.h>
#define WITNESS_COUNT 200
#define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4)
/*
* XXX: This is somewhat bogus, as we assume here that at most 1024 threads
* will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should
* probably be safe for the most part, but it's still a SWAG.
*/
#define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2
#define WITNESS_NCHILDREN 6
struct witness_child_list_entry;
struct witness {
const char *w_name;
struct lock_class *w_class;
STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */
STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */
struct witness_child_list_entry *w_children; /* Great evilness... */
const char *w_file;
int w_line;
u_int w_level;
u_int w_refcount;
u_char w_Giant_squawked:1;
u_char w_other_squawked:1;
u_char w_same_squawked:1;
};
struct witness_child_list_entry {
struct witness_child_list_entry *wcl_next;
struct witness *wcl_children[WITNESS_NCHILDREN];
u_int wcl_count;
};
STAILQ_HEAD(witness_list, witness);
struct witness_blessed {
const char *b_lock1;
const char *b_lock2;
};
struct witness_order_list_entry {
const char *w_name;
struct lock_class *w_class;
};
static struct witness *enroll(const char *description,
struct lock_class *lock_class);
static int itismychild(struct witness *parent, struct witness *child);
static void removechild(struct witness *parent, struct witness *child);
static int isitmychild(struct witness *parent, struct witness *child);
static int isitmydescendant(struct witness *parent, struct witness *child);
static int blessed(struct witness *, struct witness *);
static void witness_display_list(void(*prnt)(const char *fmt, ...),
struct witness_list *list);
static void witness_displaydescendants(void(*)(const char *fmt, ...),
struct witness *);
static void witness_leveldescendents(struct witness *parent, int level);
static void witness_levelall(void);
static struct witness *witness_get(void);
static void witness_free(struct witness *m);
static struct witness_child_list_entry *witness_child_get(void);
static void witness_child_free(struct witness_child_list_entry *wcl);
static struct lock_list_entry *witness_lock_list_get(void);
static void witness_lock_list_free(struct lock_list_entry *lle);
static void witness_display(void(*)(const char *fmt, ...));
static struct lock_instance *find_instance(struct lock_list_entry *lock_list,
struct lock_object *lock);
MALLOC_DEFINE(M_WITNESS, "witness", "witness structure");
static int witness_watch = 1;
TUNABLE_INT("debug.witness_watch", &witness_watch);
SYSCTL_INT(_debug, OID_AUTO, witness_watch, CTLFLAG_RD, &witness_watch, 0, "");
#ifdef DDB
/*
* When DDB is enabled and witness_ddb 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.
*/
#ifdef WITNESS_DDB
int witness_ddb = 1;
#else
int witness_ddb = 0;
#endif
TUNABLE_INT("debug.witness_ddb", &witness_ddb);
SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, "");
#endif /* DDB */
#ifdef WITNESS_SKIPSPIN
int witness_skipspin = 1;
#else
int witness_skipspin = 0;
#endif
TUNABLE_INT("debug.witness_skipspin", &witness_skipspin);
SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0,
"");
static struct mtx w_mtx;
static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
static struct witness_child_list_entry *w_child_free = NULL;
static struct lock_list_entry *w_lock_list_free = NULL;
static int witness_dead; /* fatal error, probably no memory */
static struct witness w_data[WITNESS_COUNT];
static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT];
static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
static struct witness_order_list_entry order_lists[] = {
{ "Giant", &lock_class_mtx_sleep },
{ "pgrpsess", &lock_class_sx },
{ "proctree", &lock_class_sx },
{ "allproc", &lock_class_sx },
{ "process group", &lock_class_mtx_sleep },
{ "process lock", &lock_class_mtx_sleep },
{ "session", &lock_class_mtx_sleep },
{ "uidinfo hash", &lock_class_mtx_sleep },
{ "uidinfo struct", &lock_class_mtx_sleep },
{ NULL, NULL },
/*
* spin locks
*/
#ifdef SMP
{ "ap boot", &lock_class_mtx_spin },
#ifdef __i386__
{ "com", &lock_class_mtx_spin },
#endif
#endif
{ "sio", &lock_class_mtx_spin },
#ifdef __i386__
{ "cy", &lock_class_mtx_spin },
#endif
{ "ng_node", &lock_class_mtx_spin },
{ "ng_worklist", &lock_class_mtx_spin },
{ "ithread table lock", &lock_class_mtx_spin },
{ "sched lock", &lock_class_mtx_spin },
{ "callout", &lock_class_mtx_spin },
/*
* leaf locks
*/
{ "allpmaps", &lock_class_mtx_spin },
{ "icu", &lock_class_mtx_spin },
#ifdef SMP
{ "smp rendezvous", &lock_class_mtx_spin },
#endif
{ "clk", &lock_class_mtx_spin },
{ NULL, NULL },
{ NULL, 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);
/*
* List of all locks in the system.
*/
STAILQ_HEAD(, lock_object) all_locks = STAILQ_HEAD_INITIALIZER(all_locks);
static struct mtx all_mtx = {
{ &lock_class_mtx_sleep, /* mtx_object.lo_class */
"All locks list", /* mtx_object.lo_name */
LO_INITIALIZED, /* mtx_object.lo_flags */
{ NULL }, /* mtx_object.lo_list */
NULL }, /* mtx_object.lo_witness */
MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */
TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
{ NULL, NULL } /* mtx_contested */
};
/*
* This global is set to 0 once it becomes safe to use the witness code.
*/
static int witness_cold = 1;
/*
* Global variables for book keeping.
*/
static int lock_cur_cnt;
static int lock_max_cnt;
/*
* The WITNESS-enabled diagnostic code.
*/
static void
witness_initialize(void *dummy __unused)
{
struct lock_object *lock;
struct witness_order_list_entry *order;
struct witness *w, *w1;
int i;
/*
* We have to release Giant before initializing its witness
* structure so that WITNESS doesn't get confused.
*/
mtx_unlock(&Giant);
mtx_assert(&Giant, MA_NOTOWNED);
CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
STAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list);
mtx_init(&w_mtx, "witness lock", MTX_SPIN | MTX_QUIET | MTX_NOWITNESS);
for (i = 0; i < WITNESS_COUNT; i++)
witness_free(&w_data[i]);
for (i = 0; i < WITNESS_CHILDCOUNT; i++)
witness_child_free(&w_childdata[i]);
for (i = 0; i < LOCK_CHILDCOUNT; i++)
witness_lock_list_free(&w_locklistdata[i]);
/* First add in all the specified order lists. */
for (order = order_lists; order->w_name != NULL; order++) {
w = enroll(order->w_name, order->w_class);
if (w == NULL)
continue;
w->w_file = "order list";
for (order++; order->w_name != NULL; order++) {
w1 = enroll(order->w_name, order->w_class);
if (w1 == NULL)
continue;
w1->w_file = "order list";
itismychild(w, w1);
w = w1;
}
}
/* Iterate through all locks and add them to witness. */
mtx_lock(&all_mtx);
STAILQ_FOREACH(lock, &all_locks, lo_list) {
if (lock->lo_flags & LO_WITNESS)
lock->lo_witness = enroll(lock->lo_name,
lock->lo_class);
else
lock->lo_witness = NULL;
}
mtx_unlock(&all_mtx);
/* Mark the witness code as being ready for use. */
atomic_store_rel_int(&witness_cold, 0);
mtx_lock(&Giant);
}
SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL)
void
witness_init(struct lock_object *lock)
{
struct lock_class *class;
class = lock->lo_class;
if (lock->lo_flags & LO_INITIALIZED)
panic("%s: lock (%s) %s is already initialized", __func__,
class->lc_name, lock->lo_name);
if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
(class->lc_flags & LC_RECURSABLE) == 0)
panic("%s: lock (%s) %s can not be recursable", __func__,
class->lc_name, lock->lo_name);
if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
(class->lc_flags & LC_SLEEPABLE) == 0)
panic("%s: lock (%s) %s can not be sleepable", __func__,
class->lc_name, lock->lo_name);
if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
(class->lc_flags & LC_UPGRADABLE) == 0)
panic("%s: lock (%s) %s can not be upgradable", __func__,
class->lc_name, lock->lo_name);
mtx_lock(&all_mtx);
STAILQ_INSERT_TAIL(&all_locks, lock, lo_list);
lock->lo_flags |= LO_INITIALIZED;
lock_cur_cnt++;
if (lock_cur_cnt > lock_max_cnt)
lock_max_cnt = lock_cur_cnt;
mtx_unlock(&all_mtx);
if (!witness_cold && !witness_dead && panicstr == NULL &&
(lock->lo_flags & LO_WITNESS) != 0)
lock->lo_witness = enroll(lock->lo_name, class);
else
lock->lo_witness = NULL;
}
void
witness_destroy(struct lock_object *lock)
{
struct witness *w;
if (witness_cold)
panic("lock (%s) %s destroyed while witness_cold",
lock->lo_class->lc_name, lock->lo_name);
if ((lock->lo_flags & LO_INITIALIZED) == 0)
panic("%s: lock (%s) %s is not initialized", __func__,
lock->lo_class->lc_name, lock->lo_name);
/* XXX: need to verify that no one holds the lock */
w = lock->lo_witness;
if (w != NULL) {
mtx_lock_spin(&w_mtx);
w->w_refcount--;
if (w->w_refcount == 0) {
CTR2(KTR_WITNESS,
"%s: marking witness %s as dead", __func__, w->w_name);
w->w_name = "(dead)";
w->w_file = "(dead)";
w->w_line = 0;
}
mtx_unlock_spin(&w_mtx);
}
mtx_lock(&all_mtx);
lock_cur_cnt--;
STAILQ_REMOVE(&all_locks, lock, lock_object, lo_list);
lock->lo_flags &= ~LO_INITIALIZED;
mtx_unlock(&all_mtx);
}
static void
witness_display_list(void(*prnt)(const char *fmt, ...),
struct witness_list *list)
{
struct witness *w, *w1;
int found;
STAILQ_FOREACH(w, list, w_typelist) {
if (w->w_file == NULL)
continue;
found = 0;
STAILQ_FOREACH(w1, list, w_typelist) {
if (isitmychild(w1, w)) {
found++;
break;
}
}
if (found)
continue;
/*
* This lock has no anscestors, display its descendants.
*/
witness_displaydescendants(prnt, w);
}
}
static void
witness_display(void(*prnt)(const char *fmt, ...))
{
struct witness *w;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
witness_levelall();
/*
* First, handle sleep locks which have been acquired at least
* once.
*/
prnt("Sleep locks:\n");
witness_display_list(prnt, &w_sleep);
/*
* Now do spin locks which have been acquired at least once.
*/
prnt("\nSpin locks:\n");
witness_display_list(prnt, &w_spin);
/*
* Finally, any locks which have not been acquired yet.
*/
prnt("\nLocks which were never acquired:\n");
STAILQ_FOREACH(w, &w_all, w_list) {
if (w->w_file != NULL)
continue;
prnt("%s\n", w->w_name);
}
}
void
witness_lock(struct lock_object *lock, int flags, const char *file, int line)
{
struct lock_list_entry **lock_list, *lle;
struct lock_instance *lock1, *lock2;
struct lock_class *class;
struct witness *w, *w1;
struct thread *td;
int i, j;
#ifdef DDB
int go_into_ddb = 0;
#endif /* DDB */
if (witness_cold || witness_dead || lock->lo_witness == NULL ||
panicstr != NULL)
return;
w = lock->lo_witness;
class = lock->lo_class;
td = curthread;
if (class->lc_flags & LC_SLEEPLOCK) {
if (td->td_critnest != 0 && (flags & LOP_TRYLOCK) == 0)
panic("blockable sleep lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
lock_list = &td->td_sleeplocks;
} else
lock_list = PCPU_PTR(spinlocks);
/*
* Try locks do not block if they fail to acquire the lock, thus
* there is no danger of deadlocks or of switching while holding a
* spin lock if we acquire a lock via a try operation.
*/
if (flags & LOP_TRYLOCK)
goto out;
/*
* Is this the first lock acquired? If so, then no order checking
* is needed.
*/
if (*lock_list == NULL)
goto out;
/*
* Check to see if we are recursing on a lock we already own.
*/
lock1 = find_instance(*lock_list, lock);
if (lock1 != NULL) {
if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
(flags & LOP_EXCLUSIVE) == 0) {
printf("shared lock of (%s) %s @ %s:%d\n",
class->lc_name, lock->lo_name, file, line);
printf("while exclusively locked from %s:%d\n",
lock1->li_file, lock1->li_line);
panic("share->excl");
}
if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
(flags & LOP_EXCLUSIVE) != 0) {
printf("exclusive lock of (%s) %s @ %s:%d\n",
class->lc_name, lock->lo_name, file, line);
printf("while share locked from %s:%d\n",
lock1->li_file, lock1->li_line);
panic("excl->share");
}
lock1->li_flags++;
if ((lock->lo_flags & LO_RECURSABLE) == 0) {
printf(
"recursed on non-recursive lock (%s) %s @ %s:%d\n",
class->lc_name, lock->lo_name, file, line);
printf("first acquired @ %s:%d\n", lock1->li_file,
lock1->li_line);
panic("recurse");
}
CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
td->td_proc->p_pid, lock->lo_name,
lock1->li_flags & LI_RECURSEMASK);
lock1->li_file = file;
lock1->li_line = line;
return;
}
/*
* Check for duplicate locks of the same type. Note that we only
* have to check for this on the last lock we just acquired. Any
* other cases will be caught as lock order violations.
*/
lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1];
w1 = lock1->li_lock->lo_witness;
if (w1 == w) {
if (w->w_same_squawked || (lock->lo_flags & LO_DUPOK))
goto out;
w->w_same_squawked = 1;
printf("acquiring duplicate lock of same type: \"%s\"\n",
lock->lo_name);
printf(" 1st @ %s:%d\n", lock1->li_file, lock1->li_line);
printf(" 2nd @ %s:%d\n", file, line);
#ifdef DDB
go_into_ddb = 1;
#endif /* DDB */
goto out;
}
MPASS(!mtx_owned(&w_mtx));
mtx_lock_spin(&w_mtx);
/*
* If we have a known higher number just say ok
*/
if (witness_watch > 1 && w->w_level > w1->w_level) {
mtx_unlock_spin(&w_mtx);
goto out;
}
if (isitmydescendant(w1, w)) {
mtx_unlock_spin(&w_mtx);
goto out;
}
for (j = 0, lle = *lock_list; lle != NULL; lle = lle->ll_next) {
for (i = lle->ll_count - 1; i >= 0; i--, j++) {
MPASS(j < WITNESS_COUNT);
lock1 = &lle->ll_children[i];
w1 = lock1->li_lock->lo_witness;
/*
* If this lock doesn't undergo witness checking,
* then skip it.
*/
if (w1 == NULL) {
KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
("lock missing witness structure"));
continue;
}
/*
* If we are locking Giant and we slept with this
* lock, then skip it.
*/
if ((lock1->li_flags & LI_SLEPT) != 0 &&
lock == &Giant.mtx_object)
continue;
if (!isitmydescendant(w, w1))
continue;
/*
* We have a lock order violation, check to see if it
* is allowed or has already been yelled about.
*/
mtx_unlock_spin(&w_mtx);
if (blessed(w, w1))
goto out;
if (lock1->li_lock == &Giant.mtx_object) {
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;
}
/*
* Ok, yell about it.
*/
printf("lock order reversal\n");
/*
* Try to locate an earlier lock with
* witness w in our list.
*/
do {
lock2 = &lle->ll_children[i];
MPASS(lock2->li_lock != NULL);
if (lock2->li_lock->lo_witness == w)
break;
i--;
if (i == 0 && lle->ll_next != NULL) {
lle = lle->ll_next;
i = lle->ll_count - 1;
MPASS(i != 0);
}
} while (i >= 0);
if (i < 0) {
printf(" 1st %p %s @ %s:%d\n", lock1->li_lock,
lock1->li_lock->lo_name, lock1->li_file,
lock1->li_line);
printf(" 2nd %p %s @ %s:%d\n", lock,
lock->lo_name, file, line);
} else {
printf(" 1st %p %s @ %s:%d\n", lock2->li_lock,
lock2->li_lock->lo_name, lock2->li_file,
lock2->li_line);
printf(" 2nd %p %s @ %s:%d\n", lock1->li_lock,
lock1->li_lock->lo_name, lock1->li_file,
lock1->li_line);
printf(" 3rd %p %s @ %s:%d\n", lock,
lock->lo_name, file, line);
}
#ifdef DDB
go_into_ddb = 1;
#endif /* DDB */
goto out;
}
}
lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1];
/*
* Don't build a new relationship if we are locking Giant just
* after waking up and the previous lock in the list was acquired
* prior to blocking.
*/
if (lock == &Giant.mtx_object && (lock1->li_flags & LI_SLEPT) != 0)
mtx_unlock_spin(&w_mtx);
else {
CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
lock->lo_name, lock1->li_lock->lo_name);
if (!itismychild(lock1->li_lock->lo_witness, w))
mtx_unlock_spin(&w_mtx);
}
out:
#ifdef DDB
if (witness_ddb && go_into_ddb)
Debugger(__func__);
#endif /* DDB */
w->w_file = file;
w->w_line = line;
lle = *lock_list;
if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
lle = witness_lock_list_get();
if (lle == NULL)
return;
lle->ll_next = *lock_list;
CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
td->td_proc->p_pid, lle);
*lock_list = lle;
}
lock1 = &lle->ll_children[lle->ll_count++];
lock1->li_lock = lock;
lock1->li_line = line;
lock1->li_file = file;
if ((flags & LOP_EXCLUSIVE) != 0)
lock1->li_flags = LI_EXCLUSIVE;
else
lock1->li_flags = 0;
CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
}
void
witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
{
struct lock_instance *instance;
struct lock_class *class;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_dead || panicstr != NULL)
return;
class = lock->lo_class;
if ((lock->lo_flags & LO_UPGRADABLE) == 0)
panic("upgrade of non-upgradable lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((flags & LOP_TRYLOCK) == 0)
panic("non-try upgrade of lock (%s) %s @ %s:%d", class->lc_name,
lock->lo_name, file, line);
if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0)
panic("upgrade of non-sleep lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
instance = find_instance(curthread->td_sleeplocks, lock);
if (instance == NULL)
panic("upgrade of unlocked lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((instance->li_flags & LI_EXCLUSIVE) != 0)
panic("upgrade of exclusive lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((instance->li_flags & LI_RECURSEMASK) != 0)
panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d",
class->lc_name, lock->lo_name,
instance->li_flags & LI_RECURSEMASK, file, line);
instance->li_flags |= LI_EXCLUSIVE;
}
void
witness_downgrade(struct lock_object *lock, int flags, const char *file,
int line)
{
struct lock_instance *instance;
struct lock_class *class;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_dead || panicstr != NULL)
return;
class = lock->lo_class;
if ((lock->lo_flags & LO_UPGRADABLE) == 0)
panic("downgrade of non-upgradable lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0)
panic("downgrade of non-sleep lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
instance = find_instance(curthread->td_sleeplocks, lock);
if (instance == NULL)
panic("downgrade of unlocked lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((instance->li_flags & LI_EXCLUSIVE) == 0)
panic("downgrade of shared lock (%s) %s @ %s:%d",
class->lc_name, lock->lo_name, file, line);
if ((instance->li_flags & LI_RECURSEMASK) != 0)
panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d",
class->lc_name, lock->lo_name,
instance->li_flags & LI_RECURSEMASK, file, line);
instance->li_flags &= ~LI_EXCLUSIVE;
}
void
witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
{
struct lock_list_entry **lock_list, *lle;
struct lock_instance *instance;
struct lock_class *class;
struct thread *td;
register_t s;
int i, j;
if (witness_cold || witness_dead || lock->lo_witness == NULL ||
panicstr != NULL)
return;
td = curthread;
class = lock->lo_class;
if (class->lc_flags & LC_SLEEPLOCK)
lock_list = &td->td_sleeplocks;
else
lock_list = PCPU_PTR(spinlocks);
for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
for (i = 0; i < (*lock_list)->ll_count; i++) {
instance = &(*lock_list)->ll_children[i];
if (instance->li_lock == lock) {
if ((instance->li_flags & LI_EXCLUSIVE) != 0 &&
(flags & LOP_EXCLUSIVE) == 0) {
printf(
"shared unlock of (%s) %s @ %s:%d\n",
class->lc_name, lock->lo_name,
file, line);
printf(
"while exclusively locked from %s:%d\n",
instance->li_file,
instance->li_line);
panic("excl->ushare");
}
if ((instance->li_flags & LI_EXCLUSIVE) == 0 &&
(flags & LOP_EXCLUSIVE) != 0) {
printf(
"exclusive unlock of (%s) %s @ %s:%d\n",
class->lc_name, lock->lo_name,
file, line);
printf(
"while share locked from %s:%d\n",
instance->li_file,
instance->li_line);
panic("share->uexcl");
}
/* If we are recursed, unrecurse. */
if ((instance->li_flags & LI_RECURSEMASK) > 0) {
CTR4(KTR_WITNESS,
"%s: pid %d unrecursed on %s r=%d", __func__,
td->td_proc->p_pid,
instance->li_lock->lo_name,
instance->li_flags);
instance->li_flags--;
return;
}
s = intr_disable();
CTR4(KTR_WITNESS,
"%s: pid %d removed %s from lle[%d]", __func__,
td->td_proc->p_pid,
instance->li_lock->lo_name,
(*lock_list)->ll_count - 1);
(*lock_list)->ll_count--;
for (j = i; j < (*lock_list)->ll_count; j++)
(*lock_list)->ll_children[j] =
(*lock_list)->ll_children[j + 1];
intr_restore(s);
if ((*lock_list)->ll_count == 0) {
lle = *lock_list;
*lock_list = lle->ll_next;
CTR3(KTR_WITNESS,
"%s: pid %d removed lle %p", __func__,
td->td_proc->p_pid, lle);
witness_lock_list_free(lle);
}
return;
}
}
panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name,
file, line);
}
/*
* Warn if any held locks are not sleepable. Note that Giant and the lock
* passed in are both special cases since they are both released during the
* sleep process and aren't actually held while the thread is asleep.
*/
int
witness_sleep(int check_only, struct lock_object *lock, const char *file,
int line)
{
struct lock_list_entry **lock_list, *lle;
struct lock_instance *lock1;
struct thread *td;
int i, n;
if (witness_dead || panicstr != NULL)
return (0);
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
n = 0;
/*
* Preemption bad because we need PCPU_PTR(spinlocks) to not change.
*/
critical_enter();
td = curthread;
lock_list = &td->td_sleeplocks;
again:
for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
for (i = lle->ll_count - 1; i >= 0; i--) {
lock1 = &lle->ll_children[i];
if (lock1->li_lock == lock ||
lock1->li_lock == &Giant.mtx_object)
continue;
if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) {
if (check_only == 0) {
CTR3(KTR_WITNESS,
"pid %d: sleeping with lock (%s) %s held",
td->td_proc->p_pid,
lock1->li_lock->lo_class->lc_name,
lock1->li_lock->lo_name);
lock1->li_flags |= LI_SLEPT;
}
continue;
}
n++;
printf("%s:%d: %s with \"%s\" locked from %s:%d\n",
file, line, check_only ? "could sleep" : "sleeping",
lock1->li_lock->lo_name, lock1->li_file,
lock1->li_line);
}
if (lock_list == &td->td_sleeplocks) {
lock_list = PCPU_PTR(spinlocks);
goto again;
}
#ifdef DDB
if (witness_ddb && n)
Debugger(__func__);
#endif /* DDB */
critical_exit();
return (n);
}
static struct witness *
enroll(const char *description, struct lock_class *lock_class)
{
struct witness *w;
if (!witness_watch || witness_dead || panicstr != NULL)
return (NULL);
if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin)
return (NULL);
mtx_lock_spin(&w_mtx);
STAILQ_FOREACH(w, &w_all, w_list) {
if (strcmp(description, w->w_name) == 0) {
w->w_refcount++;
mtx_unlock_spin(&w_mtx);
if (lock_class != w->w_class)
panic(
"lock (%s) %s does not match earlier (%s) lock",
description, lock_class->lc_name,
w->w_class->lc_name);
return (w);
}
}
/*
* This isn't quite right, as witness_cold is still 0 while we
* enroll all the locks initialized before witness_initialize().
*/
if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) {
mtx_unlock_spin(&w_mtx);
panic("spin lock %s not in order list", description);
}
if ((w = witness_get()) == NULL)
return (NULL);
w->w_name = description;
w->w_class = lock_class;
w->w_refcount = 1;
STAILQ_INSERT_HEAD(&w_all, w, w_list);
if (lock_class->lc_flags & LC_SPINLOCK)
STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
else if (lock_class->lc_flags & LC_SLEEPLOCK)
STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
else {
mtx_unlock_spin(&w_mtx);
panic("lock class %s is not sleep or spin",
lock_class->lc_name);
}
mtx_unlock_spin(&w_mtx);
return (w);
}
static int
itismychild(struct witness *parent, struct witness *child)
{
static int recursed;
struct witness_child_list_entry **wcl;
struct witness_list *list;
MPASS(child != NULL && parent != NULL);
if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) !=
(child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)))
panic(
"%s: parent (%s) and child (%s) are not the same lock type",
__func__, parent->w_class->lc_name,
child->w_class->lc_name);
/*
* Insert "child" after "parent"
*/
wcl = &parent->w_children;
while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN)
wcl = &(*wcl)->wcl_next;
if (*wcl == NULL) {
*wcl = witness_child_get();
if (*wcl == NULL)
return (1);
}
(*wcl)->wcl_children[(*wcl)->wcl_count++] = child;
/*
* Now prune whole tree. We look for cases where a lock is now
* both a descendant and a direct child of a given lock. In that
* case, we want to remove the direct child link from the tree.
*/
if (recursed)
return (0);
recursed = 1;
if (parent->w_class->lc_flags & LC_SLEEPLOCK)
list = &w_sleep;
else
list = &w_spin;
STAILQ_FOREACH(child, list, w_typelist) {
STAILQ_FOREACH(parent, list, w_typelist) {
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_child_list_entry **wcl, *wcl1;
int i;
for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next)
for (i = 0; i < (*wcl)->wcl_count; i++)
if ((*wcl)->wcl_children[i] == child)
goto found;
return;
found:
(*wcl)->wcl_count--;
if ((*wcl)->wcl_count > i)
(*wcl)->wcl_children[i] =
(*wcl)->wcl_children[(*wcl)->wcl_count];
MPASS((*wcl)->wcl_children[i] != NULL);
if ((*wcl)->wcl_count != 0)
return;
wcl1 = *wcl;
*wcl = wcl1->wcl_next;
witness_child_free(wcl1);
}
static int
isitmychild(struct witness *parent, struct witness *child)
{
struct witness_child_list_entry *wcl;
int i;
for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) {
for (i = 0; i < wcl->wcl_count; i++) {
if (wcl->wcl_children[i] == child)
return (1);
}
}
return (0);
}
static int
isitmydescendant(struct witness *parent, struct witness *child)
{
struct witness_child_list_entry *wcl;
int i, j;
if (isitmychild(parent, child))
return (1);
j = 0;
for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) {
MPASS(j < 1000);
for (i = 0; i < wcl->wcl_count; i++) {
if (isitmydescendant(wcl->wcl_children[i], child))
return (1);
}
j++;
}
return (0);
}
void
witness_levelall (void)
{
struct witness_list *list;
struct witness *w, *w1;
/*
* First clear all levels.
*/
STAILQ_FOREACH(w, &w_all, w_list) {
w->w_level = 0;
}
/*
* Look for locks with no parent and level all their descendants.
*/
STAILQ_FOREACH(w, &w_all, w_list) {
/*
* This is just an optimization, technically we could get
* away just walking the all list each time.
*/
if (w->w_class->lc_flags & LC_SLEEPLOCK)
list = &w_sleep;
else
list = &w_spin;
STAILQ_FOREACH(w1, list, w_typelist) {
if (isitmychild(w1, w))
goto skip;
}
witness_leveldescendents(w, 0);
skip:
}
}
static void
witness_leveldescendents(struct witness *parent, int level)
{
struct witness_child_list_entry *wcl;
int i;
if (parent->w_level < level)
parent->w_level = level;
level++;
for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next)
for (i = 0; i < wcl->wcl_count; i++)
witness_leveldescendents(wcl->wcl_children[i], level);
}
static void
witness_displaydescendants(void(*prnt)(const char *fmt, ...),
struct witness *parent)
{
struct witness_child_list_entry *wcl;
int i, level;
level = parent->w_level;
prnt("%-2d", level);
for (i = 0; i < level; i++)
prnt(" ");
prnt("%s", parent->w_name);
if (parent->w_file != NULL)
prnt(" -- last acquired @ %s:%d\n", parent->w_file,
parent->w_line);
for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next)
for (i = 0; i < wcl->wcl_count; i++)
witness_displaydescendants(prnt,
wcl->wcl_children[i]);
}
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_name, b->b_lock1) == 0) {
if (strcmp(w2->w_name, b->b_lock2) == 0)
return (1);
continue;
}
if (strcmp(w1->w_name, b->b_lock2) == 0)
if (strcmp(w2->w_name, b->b_lock1) == 0)
return (1);
}
return (0);
}
static struct witness *
witness_get(void)
{
struct witness *w;
if (witness_dead) {
mtx_unlock_spin(&w_mtx);
return (NULL);
}
if (STAILQ_EMPTY(&w_free)) {
witness_dead = 1;
mtx_unlock_spin(&w_mtx);
printf("%s: witness exhausted\n", __func__);
return (NULL);
}
w = STAILQ_FIRST(&w_free);
STAILQ_REMOVE_HEAD(&w_free, w_list);
bzero(w, sizeof(*w));
return (w);
}
static void
witness_free(struct witness *w)
{
STAILQ_INSERT_HEAD(&w_free, w, w_list);
}
static struct witness_child_list_entry *
witness_child_get(void)
{
struct witness_child_list_entry *wcl;
if (witness_dead) {
mtx_unlock_spin(&w_mtx);
return (NULL);
}
wcl = w_child_free;
if (wcl == NULL) {
witness_dead = 1;
mtx_unlock_spin(&w_mtx);
printf("%s: witness exhausted\n", __func__);
return (NULL);
}
w_child_free = wcl->wcl_next;
bzero(wcl, sizeof(*wcl));
return (wcl);
}
static void
witness_child_free(struct witness_child_list_entry *wcl)
{
wcl->wcl_next = w_child_free;
w_child_free = wcl;
}
static struct lock_list_entry *
witness_lock_list_get(void)
{
struct lock_list_entry *lle;
if (witness_dead)
return (NULL);
mtx_lock_spin(&w_mtx);
lle = w_lock_list_free;
if (lle == NULL) {
witness_dead = 1;
mtx_unlock_spin(&w_mtx);
printf("%s: witness exhausted\n", __func__);
return (NULL);
}
w_lock_list_free = lle->ll_next;
mtx_unlock_spin(&w_mtx);
bzero(lle, sizeof(*lle));
return (lle);
}
static void
witness_lock_list_free(struct lock_list_entry *lle)
{
mtx_lock_spin(&w_mtx);
lle->ll_next = w_lock_list_free;
w_lock_list_free = lle;
mtx_unlock_spin(&w_mtx);
}
static struct lock_instance *
find_instance(struct lock_list_entry *lock_list, struct lock_object *lock)
{
struct lock_list_entry *lle;
struct lock_instance *instance;
int i;
for (lle = lock_list; lle != NULL; lle = lle->ll_next)
for (i = lle->ll_count - 1; i >= 0; i--) {
instance = &lle->ll_children[i];
if (instance->li_lock == lock)
return (instance);
}
return (NULL);
}
int
witness_list_locks(struct lock_list_entry **lock_list)
{
struct lock_list_entry *lle;
struct lock_instance *instance;
struct lock_object *lock;
int i, nheld;
nheld = 0;
for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
for (i = lle->ll_count - 1; i >= 0; i--) {
instance = &lle->ll_children[i];
lock = instance->li_lock;
printf("%s (%s) %s (%p) locked @ %s:%d\n",
(instance->li_flags & LI_EXCLUSIVE) != 0 ?
"exclusive" : "shared",
lock->lo_class->lc_name, lock->lo_name, lock,
instance->li_file, instance->li_line);
nheld++;
}
return (nheld);
}
/*
* Calling this on td != curthread is bad unless we are in ddb.
*/
int
witness_list(struct thread *td)
{
int nheld;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
#ifdef DDB
KASSERT(td == curthread || db_active,
("%s: td != curthread and we aren't in the debugger", __func__));
if (!db_active && witness_dead)
return (0);
#else
KASSERT(td == curthread, ("%s: p != curthread", __func__));
if (witness_dead)
return (0);
#endif
nheld = witness_list_locks(&td->td_sleeplocks);
/*
* We only handle spinlocks if td == curthread. This is somewhat broken
* if td is currently executing on some other CPU and holds spin locks
* as we won't display those locks. If we had a MI way of getting
* the per-cpu data for a given cpu then we could use
* td->td_kse->ke_oncpu to get the list of spinlocks for this thread
* and "fix" this.
*
* That still wouldn't really fix this unless we locked sched_lock
* or stopped the other CPU to make sure it wasn't changing the list
* out from under us. It is probably best to just not try to handle
* threads on other CPU's for now.
*/
if (td == curthread) {
/*
* Preemption bad because we need PCPU_PTR(spinlocks) to not
* change.
*/
critical_enter();
nheld += witness_list_locks(PCPU_PTR(spinlocks));
critical_exit();
}
return (nheld);
}
void
witness_save(struct lock_object *lock, const char **filep, int *linep)
{
struct lock_instance *instance;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_dead || panicstr != NULL)
return;
if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0)
panic("%s: lock (%s) %s is not a sleep lock", __func__,
lock->lo_class->lc_name, lock->lo_name);
instance = find_instance(curthread->td_sleeplocks, lock);
if (instance == NULL)
panic("%s: lock (%s) %s not locked", __func__,
lock->lo_class->lc_name, lock->lo_name);
*filep = instance->li_file;
*linep = instance->li_line;
}
void
witness_restore(struct lock_object *lock, const char *file, int line)
{
struct lock_instance *instance;
KASSERT(!witness_cold, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_dead || panicstr != NULL)
return;
if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) == 0)
panic("%s: lock (%s) %s is not a sleep lock", __func__,
lock->lo_class->lc_name, lock->lo_name);
instance = find_instance(curthread->td_sleeplocks, lock);
if (instance == NULL)
panic("%s: lock (%s) %s not locked", __func__,
lock->lo_class->lc_name, lock->lo_name);
lock->lo_witness->w_file = file;
lock->lo_witness->w_line = line;
instance->li_file = file;
instance->li_line = line;
}
void
witness_assert(struct lock_object *lock, int flags, const char *file, int line)
{
#ifdef INVARIANT_SUPPORT
struct lock_instance *instance;
if (lock->lo_witness == NULL || witness_dead || panicstr != NULL)
return;
if ((lock->lo_class->lc_flags & LC_SLEEPLOCK) != 0)
instance = find_instance(curthread->td_sleeplocks, lock);
else if ((lock->lo_class->lc_flags & LC_SPINLOCK) != 0)
instance = find_instance(PCPU_GET(spinlocks), lock);
else {
panic("Lock (%s) %s is not sleep or spin!",
lock->lo_class->lc_name, lock->lo_name);
return;
}
switch (flags) {
case LA_UNLOCKED:
if (instance != NULL)
panic("Lock (%s) %s locked @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
break;
case LA_LOCKED:
case LA_LOCKED | LA_RECURSED:
case LA_LOCKED | LA_NOTRECURSED:
case LA_SLOCKED:
case LA_SLOCKED | LA_RECURSED:
case LA_SLOCKED | LA_NOTRECURSED:
case LA_XLOCKED:
case LA_XLOCKED | LA_RECURSED:
case LA_XLOCKED | LA_NOTRECURSED:
if (instance == NULL) {
panic("Lock (%s) %s not locked @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
break;
}
if ((flags & LA_XLOCKED) != 0 &&
(instance->li_flags & LI_EXCLUSIVE) == 0)
panic("Lock (%s) %s not exclusively locked @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
if ((flags & LA_SLOCKED) != 0 &&
(instance->li_flags & LI_EXCLUSIVE) != 0)
panic("Lock (%s) %s exclusively locked @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
if ((flags & LA_RECURSED) != 0 &&
(instance->li_flags & LI_RECURSEMASK) == 0)
panic("Lock (%s) %s not recursed @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
if ((flags & LA_NOTRECURSED) != 0 &&
(instance->li_flags & LI_RECURSEMASK) != 0)
panic("Lock (%s) %s recursed @ %s:%d.",
lock->lo_class->lc_name, lock->lo_name, file, line);
break;
default:
panic("Invalid lock assertion at %s:%d.", file, line);
}
#endif /* INVARIANT_SUPPORT */
}
#ifdef DDB
DB_SHOW_COMMAND(locks, db_witness_list)
{
struct thread *td;
pid_t pid;
struct proc *p;
if (have_addr) {
pid = (addr % 16) + ((addr >> 4) % 16) * 10 +
((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 +
((addr >> 16) % 16) * 10000;
/* sx_slock(&allproc_lock); */
FOREACH_PROC_IN_SYSTEM(p) {
if (p->p_pid == pid)
break;
}
/* sx_sunlock(&allproc_lock); */
if (p == NULL) {
db_printf("pid %d not found\n", pid);
return;
}
FOREACH_THREAD_IN_PROC(p, td) {
witness_list(td);
}
} else {
td = curthread;
witness_list(td);
}
}
DB_SHOW_COMMAND(witness, db_witness_display)
{
witness_display(db_printf);
}
#endif
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