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- Make witness_watch a 3 state value.

Browse Source 
1 means that witness is up and running.
  0 means that witness is disabled but that it can be established later
    again in effective way.
  -1 means that witness is disabled permanently
- Fix a bug causing kernel to panic on witness disabling through
  witness_watch.  lock lists queues were still full of entries and this was
  causing throubles with debugging stubs (like witness_thread_exit()).

Reported by:	kris, yongari
Sponsored by:	Nokia
This commit is contained in:
Attilio Rao 2008-08-29 15:47:53 +00:00
parent 67d350d60c
commit df3310e04a
1 changed files with 42 additions and 35 deletions
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77
sys/kern/subr_witness.c
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@ -464,7 +464,7 @@ static struct witness_lock_order_data *w_lofree = NULL;
static struct witness_lock_order_hash w_lohash;
static int w_max_used_index = 0;
static unsigned int w_generation = 0;
static const char *w_notrunning = "Witness not running, witness_watch == 0\n";
static const char *w_notrunning = "Witness not running\n";
static const char *w_stillcold = "Witness is still cold\n";
@ -801,7 +801,7 @@ witness_init(struct lock_object *lock, const char *type)
* it to the pending_locks list. If it is not too early, then enroll
* the lock now.
*/
if (witness_watch == 0 || panicstr != NULL ||
if (witness_watch < 1 || panicstr != NULL ||
(lock->lo_flags & LO_WITNESS) == 0)
lock->lo_witness = NULL;
else if (witness_cold) {
@ -980,7 +980,7 @@ int
witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
{
if (witness_watch == 0 || panicstr != NULL)
if (witness_watch < 1 || panicstr != NULL)
return (0);
/* Require locks that witness knows about. */
@ -1019,7 +1019,7 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
struct thread *td;
int i, j;
if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL ||
if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
panicstr != NULL)
return;
@ -1297,7 +1297,7 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
struct witness *w;
struct thread *td;
if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL ||
if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
panicstr != NULL)
return;
w = lock->lo_witness;
@ -1356,7 +1356,7 @@ witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
struct lock_class *class;
KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL)
if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
file = fixup_filename(file);
@ -1388,7 +1388,7 @@ witness_downgrade(struct lock_object *lock, int flags, const char *file,
struct lock_class *class;
KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL)
if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
file = fixup_filename(file);
@ -1422,8 +1422,7 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
register_t s;
int i, j;
if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL ||
panicstr != NULL)
if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
return;
td = curthread;
class = LOCK_CLASS(lock);
@ -1441,12 +1440,22 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
if (instance->li_lock == lock)
goto found;
}
panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name,
file, line);
/*
* When disabling WITNESS through witness_watch we could end up in
* having registered locks in the locks list queue.
* We have to make sure we flush these queues, so just search for
* eventual registered locks and remove them.
*/
if (witness_watch > 0)
panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
lock->lo_name, file, line);
else
return;
found:
/* First, check for shared/exclusive mismatches. */
if ((instance->li_flags & LI_EXCLUSIVE) != 0 &&
if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
(flags & LOP_EXCLUSIVE) == 0) {
printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name,
lock->lo_name, file, line);
@ -1454,7 +1463,7 @@ found:
instance->li_file, instance->li_line);
panic("excl->ushare");
}
if ((instance->li_flags & LI_EXCLUSIVE) == 0 &&
if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
(flags & LOP_EXCLUSIVE) != 0) {
printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name,
lock->lo_name, file, line);
@ -1535,7 +1544,7 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
va_list ap;
int i, n;
if (witness_cold || witness_watch == 0 || panicstr != NULL)
if (witness_cold || witness_watch < 1 || panicstr != NULL)
return (0);
n = 0;
td = curthread;
@ -1596,7 +1605,7 @@ witness_file(struct lock_object *lock)
{
struct witness *w;
if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL)
if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
return ("?");
w = lock->lo_witness;
return (w->w_file);
@ -1607,7 +1616,7 @@ witness_line(struct lock_object *lock)
{
struct witness *w;
if (witness_cold || witness_watch == 0 || lock->lo_witness == NULL)
if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
return (0);
w = lock->lo_witness;
return (w->w_line);
@ -1621,7 +1630,7 @@ enroll(const char *description, struct lock_class *lock_class)
MPASS(description != NULL);
if (witness_watch == 0 || panicstr != NULL)
if (witness_watch < 1 || panicstr != NULL)
return (NULL);
if ((lock_class->lc_flags & LC_SPINLOCK)) {
if (witness_skipspin)
@ -1770,7 +1779,7 @@ adopt(struct witness *parent, struct witness *child)
i, j, w_rmatrix[i][j]);
kdb_backtrace();
printf("Witness disabled.\n");
witness_watch = 0;
witness_watch = -1;
}
if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
(w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
@ -1779,7 +1788,7 @@ adopt(struct witness *parent, struct witness *child)
j, i, w_rmatrix[j][i]);
kdb_backtrace();
printf("Witness disabled.\n");
witness_watch = 0;
witness_watch = -1;
}
}
}
@ -1831,7 +1840,7 @@ _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
i2, i1, r2);
kdb_backtrace();
printf("Witness disabled.\n");
witness_watch = 0;
witness_watch = -1;
}
return (r1 & rmask);
}
@ -1888,12 +1897,12 @@ witness_get(void)
if (witness_cold == 0)
mtx_assert(&w_mtx, MA_OWNED);
if (witness_watch == 0) {
if (witness_watch < 1) {
mtx_unlock_spin(&w_mtx);
return (NULL);
}
if (STAILQ_EMPTY(&w_free)) {
witness_watch = 0;
witness_watch = -1;
mtx_unlock_spin(&w_mtx);
printf("WITNESS: unable to allocate a new witness object\n");
return (NULL);
@ -1924,12 +1933,12 @@ witness_lock_list_get(void)
{
struct lock_list_entry *lle;
if (witness_watch == 0)
if (witness_watch == -1)
return (NULL);
mtx_lock_spin(&w_mtx);
lle = w_lock_list_free;
if (lle == NULL) {
witness_watch = 0;
witness_watch = -1;
mtx_unlock_spin(&w_mtx);
printf("%s: witness exhausted\n", __func__);
return (NULL);
@ -2046,7 +2055,7 @@ witness_save(struct lock_object *lock, const char **filep, int *linep)
struct lock_class *class;
KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL)
if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
if (class->lc_flags & LC_SLEEPLOCK)
@ -2072,7 +2081,7 @@ witness_restore(struct lock_object *lock, const char *file, int line)
struct lock_class *class;
KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL)
if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
if (class->lc_flags & LC_SLEEPLOCK)
@ -2099,7 +2108,7 @@ witness_assert(struct lock_object *lock, int flags, const char *file, int line)
struct lock_instance *instance;
struct lock_class *class;
if (lock->lo_witness == NULL || witness_watch == 0 || panicstr != NULL)
if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
if ((class->lc_flags & LC_SLEEPLOCK) != 0)
@ -2163,7 +2172,7 @@ witness_ddb_list(struct thread *td)
KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
KASSERT(kdb_active, ("%s: not in the debugger", __func__));
if (witness_watch == 0)
if (witness_watch < 1)
return;
witness_list_locks(&td->td_sleeplocks);
@ -2239,7 +2248,7 @@ sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
tmp_data2 = NULL;
tmp_w1 = NULL;
tmp_w2 = NULL;
if (witness_watch == 0) {
if (witness_watch < 1) {
error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
return (error);
}
@ -2391,7 +2400,7 @@ sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
struct sbuf *sb;
int error;
if (witness_watch == 0) {
if (witness_watch < 1) {
error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
return (error);
}
@ -2436,15 +2445,13 @@ sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
{
int error, value;
value = witness_watch;
error = sysctl_handle_int(oidp, &value, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (value == witness_watch)
return (0);
if (value != 0)
if (value > 1 || value < -1 ||
(witness_watch == -1 && value != witness_watch))
return (EINVAL);
witness_watch = 0;
witness_watch = value;
return (0);
}