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Code Issues Releases Activity

- Add a new witness_assert() to perform arbitrary locking assertions.

Browse Source 
- Clean up the KTR tracepoints to be slighlty more consistent and useful
- Fix a bug in WITNESS where we would recurse indefinitely and blow the
  stack when acquiring Giant after sleeping with a sleepable lock held.

Reported by:	tanimura (3)
This commit is contained in:
John Baldwin 2001-06-27 06:27:29 +00:00
parent 776e0b3693
commit 04297fe609
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=78871
2 changed files with 86 additions and 13 deletions
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90
sys/kern/subr_witness.c
View File

@ -284,7 +284,7 @@ witness_initialize(void *dummy __unused)
mtx_unlock(&Giant);
mtx_assert(&Giant, MA_NOTOWNED);
CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
CTR0(KTR_WITNESS, __func__ ": initializing witness");
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++)
@ -381,8 +381,8 @@ witness_destroy(struct lock_object *lock)
mtx_lock_spin(&w_mtx);
w->w_refcount--;
if (w->w_refcount == 0) {
CTR1(KTR_WITNESS, "Marking witness %s as dead",
w->w_name);
CTR1(KTR_WITNESS,
__func__ ": marking witness %s as dead", w->w_name);
w->w_name = "(dead)";
w->w_file = "(dead)";
w->w_line = 0;
@ -541,7 +541,7 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
lock1->li_line);
panic("recurse");
}
CTR3(KTR_WITNESS, "witness_lock: pid %d recursed on %s r=%d",
CTR3(KTR_WITNESS, __func__ ": pid %d recursed on %s r=%d",
curproc->p_pid, lock->lo_name,
lock1->li_flags & LI_RECURSEMASK);
lock1->li_file = file;
@ -668,10 +668,19 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
}
}
lock1 = &(*lock_list)->ll_children[(*lock_list)->ll_count - 1];
CTR2(KTR_WITNESS, "Adding %s as a child of %s", lock->lo_name,
lock1->li_lock->lo_name);
if (!itismychild(lock1->li_lock->lo_witness, w))
/*
* 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 {
CTR2(KTR_WITNESS, __func__ ": adding %s as a child of %s",
lock->lo_name, lock1->li_lock->lo_name);
if (!itismychild(lock1->li_lock->lo_witness, w))
mtx_unlock_spin(&w_mtx);
}
out:
#ifdef DDB
@ -687,7 +696,7 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
if (lle == NULL)
return;
lle->ll_next = *lock_list;
CTR2(KTR_WITNESS, "witness_lock: pid %d added lle %p",
CTR2(KTR_WITNESS, __func__ ": pid %d added lle %p",
curproc->p_pid, lle);
*lock_list = lle;
}
@ -699,7 +708,7 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
lock1->li_flags = LI_EXCLUSIVE;
else
lock1->li_flags = 0;
CTR3(KTR_WITNESS, "witness_lock: pid %d added %s as lle[%d]",
CTR3(KTR_WITNESS, __func__ ": pid %d added %s as lle[%d]",
curproc->p_pid, lock->lo_name, lle->ll_count - 1);
}
@ -753,7 +762,7 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
/* If we are recursed, unrecurse. */
if ((instance->li_flags & LI_RECURSEMASK) > 0) {
CTR3(KTR_WITNESS,
"witness_unlock: pid %d unrecursed on %s r=%d",
__func__ ": pid %d unrecursed on %s r=%d",
curproc->p_pid,
instance->li_lock->lo_name,
instance->li_flags);
@ -762,7 +771,7 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
}
s = critical_enter();
CTR3(KTR_WITNESS,
"witness_unlock: pid %d removed %s from lle[%d]",
__func__ ": pid %d removed %s from lle[%d]",
curproc->p_pid, instance->li_lock->lo_name,
(*lock_list)->ll_count - 1);
(*lock_list)->ll_count--;
@ -774,7 +783,7 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
lle = *lock_list;
*lock_list = lle->ll_next;
CTR2(KTR_WITNESS,
"witness_unlock: pid %d removed lle %p",
__func__ ": pid %d removed lle %p",
curproc->p_pid, lle);
witness_lock_list_free(lle);
}
@ -832,7 +841,7 @@ witness_sleep(int check_only, struct lock_object *lock, const char *file,
if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) {
if (check_only == 0) {
CTR3(KTR_WITNESS,
"pid %d: sleeping with (%s) %s held",
"pid %d: sleeping with lock (%s) %s held",
curproc->p_pid,
lock1->li_lock->lo_class->lc_name,
lock1->li_lock->lo_name);
@ -1336,6 +1345,61 @@ witness_restore(struct lock_object *lock, const char *file, int line)
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_class->lc_flags & LC_SLEEPLOCK) != 0)
instance = find_instance(curproc->p_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);
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);
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)

9
sys/sys/lock.h
View File

@ -81,6 +81,14 @@ struct lock_class {
#define LOP_TRYLOCK 0x00000004 /* Don't check lock order. */
#define LOP_EXCLUSIVE 0x00000008 /* Exclusive lock. */
/* Flags passed to witness_assert. */
#define LA_UNLOCKED 0x00000000 /* Lock is unlocked. */
#define LA_LOCKED 0x00000001 /* Lock is at least share locked. */
#define LA_SLOCKED 0x00000002 /* Lock is exactly share locked. */
#define LA_XLOCKED 0x00000004 /* Lock is exclusively locked. */
#define LA_RECURSED 0x00000008 /* Lock is recursed. */
#define LA_NOTRECURSED 0x00000010 /* Lock is not recursed. */
#ifdef _KERNEL
/*
* Lock instances. A lock instance is the data associated with a lock while
@ -172,6 +180,7 @@ void witness_restore(struct lock_object *, const char *, int);
int witness_list_locks(struct lock_list_entry **);
int witness_list(struct proc *);
int witness_sleep(int, struct lock_object *, const char *, int);
void witness_assert(struct lock_object *, int, const char *, int);
#ifdef WITNESS
#define WITNESS_INIT(lock) \