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Add functions WITNESS so it can be asserted that the lock is not released for a

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section of code, this uses WITNESS_NORELEASE() and WITNESS_RELEASEOK() to mark
the boundaries. Both functions require the lock to be held when calling.

This is intended for scenarios like a bus asserting that the bus lock is not
dropped during a driver call. There doesn't appear to be a man page to
document this in.

Reviewed by:	jhb
This commit is contained in:
thompsa 2009-01-21 04:19:18 +00:00
parent 48be47ddbc
commit 50e14c608e
2 changed files with 59 additions and 0 deletions
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49
sys/kern/subr_witness.c
View File

@ -127,6 +127,7 @@ __FBSDID("$FreeBSD$");
#define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */
#define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
#define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */
/* Define this to check for blessed mutexes */
#undef BLESSING
@ -367,6 +368,7 @@ static struct witness_lock_order_data *witness_lock_order_get(
struct witness *parent,
struct witness *child);
static void witness_list_lock(struct lock_instance *instance);
static void witness_setflag(struct lock_object *lock, int flag, int set);
#ifdef KDB
#define witness_debugger(c) _witness_debugger(c, __func__)
@ -1509,6 +1511,11 @@ witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
instance->li_line);
panic("share->uexcl");
}
if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
lock->lo_name, file, line);
panic("lock marked norelease");
}
/* If we are recursed, unrecurse. */
if ((instance->li_flags & LI_RECURSEMASK) > 0) {
@ -2224,6 +2231,48 @@ witness_assert(struct lock_object *lock, int flags, const char *file, int line)
#endif /* INVARIANT_SUPPORT */
}
static void
witness_setflag(struct lock_object *lock, int flag, int set)
{
struct lock_list_entry *lock_list;
struct lock_instance *instance;
struct lock_class *class;
if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
return;
class = LOCK_CLASS(lock);
if (class->lc_flags & LC_SLEEPLOCK)
lock_list = curthread->td_sleeplocks;
else {
if (witness_skipspin)
return;
lock_list = PCPU_GET(spinlocks);
}
instance = find_instance(lock_list, lock);
if (instance == NULL)
panic("%s: lock (%s) %s not locked", __func__,
class->lc_name, lock->lo_name);
if (set)
instance->li_flags |= flag;
else
instance->li_flags &= ~flag;
}
void
witness_norelease(struct lock_object *lock)
{
witness_setflag(lock, LI_NORELEASE, 1);
}
void
witness_releaseok(struct lock_object *lock)
{
witness_setflag(lock, LI_NORELEASE, 0);
}
#ifdef DDB
static void
witness_ddb_list(struct thread *td)

10
sys/sys/lock.h
View File

@ -216,6 +216,8 @@ int witness_warn(int, struct lock_object *, const char *, ...);
void witness_assert(struct lock_object *, int, const char *, int);
void witness_display_spinlock(struct lock_object *, struct thread *);
int witness_line(struct lock_object *);
void witness_norelease(struct lock_object *);
void witness_releaseok(struct lock_object *);
const char *witness_file(struct lock_object *);
void witness_thread_exit(struct thread *);
@ -267,6 +269,12 @@ void witness_thread_exit(struct thread *);
#define WITNESS_RESTORE(lock, n) \
witness_restore((lock), __CONCAT(n, __wf), __CONCAT(n, __wl))
#define WITNESS_NORELEASE(lock) \
witness_norelease(&(lock)->lock_object)
#define WITNESS_RELEASEOK(lock) \
witness_releaseok(&(lock)->lock_object)
#define WITNESS_FILE(lock) \
witness_file(lock)
@ -287,6 +295,8 @@ void witness_thread_exit(struct thread *);
#define WITNESS_SAVE_DECL(n)
#define WITNESS_SAVE(lock, n)
#define WITNESS_RESTORE(lock, n)
#define WITNESS_NORELEASE(lock)
#define WITNESS_RELEASEOK(lock)
#define WITNESS_FILE(lock) ("?")
#define WITNESS_LINE(lock) (0)
#endif /* WITNESS */