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Write a magic value into mtx_lock when destroying a mutex that will force 

all other mtx_lock() operations to block.  Previously, when the mutex was
destroyed, it would still have a valid value in mtx_lock(): either the
unowned cookie, which would allow a subsequent mtx_lock() to succeed, or a
pointer to the thread who destroyed the mutex if the mutex was locked when
it was destroyed.

MFC after:	3 days
This commit is contained in:
John Baldwin 2006-07-27 19:58:18 +00:00
parent f30e89ced3
commit 186abbd727
2 changed files with 16 additions and 0 deletions
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11
sys/kern/kern_mutex.c
View File

@ -276,6 +276,8 @@ _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_lock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep,
("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
@ -301,6 +303,8 @@ _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep,
("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
@ -380,6 +384,8 @@ _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin,
("mtx_lock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
@ -396,6 +402,8 @@ _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
MPASS(curthread != NULL);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_spin,
("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
@ -417,6 +425,8 @@ _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
int rval;
MPASS(curthread != NULL);
KASSERT(m->mtx_lock != MTX_DESTROYED,
("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
KASSERT(LOCK_CLASS(&m->mtx_object) == &lock_class_mtx_sleep,
("mtx_trylock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
@ -885,6 +895,7 @@ mtx_destroy(struct mtx *m)
__LINE__);
}
m->mtx_lock = MTX_DESTROYED;
lock_destroy(&m->mtx_object);
}

5
sys/sys/mutex.h
View File

@ -73,6 +73,11 @@
#define MTX_UNOWNED 0x00000004 /* Cookie for free mutex */
#define MTX_FLAGMASK (MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED)
/*
* Value stored in mutex->mtx_lock to denote a destroyed mutex.
*/
#define MTX_DESTROYED (MTX_CONTESTED | MTX_UNOWNED)
#endif /* _KERNEL */
#ifndef LOCORE