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- Allow mtx_trylock() to recurse on a recursive mutex. Attempts to recurse

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on a non-recursive mutex will fail but will not trigger any assertions.
- Add an assertion to mtx_lock() that one never recurses on a non-recursive
  mutex.  This is mostly useful for the non-WITNESS case.

Requested by:	deischen, julian, others (1)
This commit is contained in:
John Baldwin 2004-01-05 23:09:51 +00:00
parent 973e839bed
commit eac097962f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=124161
1 changed files with 11 additions and 5 deletions
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16
sys/kern/kern_mutex.c
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@ -338,10 +338,8 @@ _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
/*
* The important part of mtx_trylock{,_flags}()
* Tries to acquire lock `m.' We do NOT handle recursion here. If this
* function is called on a recursed mutex, it will return failure and
* will not recursively acquire the lock. You are expected to know what
* you are doing.
* Tries to acquire lock `m.' If this function is called on a mutex that
* is already owned, it will recursively acquire the lock.
*/
int
_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
@ -350,7 +348,12 @@ _mtx_trylock(struct mtx *m, int opts, const char *file, int line)
MPASS(curthread != NULL);
rval = _obtain_lock(m, curthread);
if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
rval = 1;
} else
rval = _obtain_lock(m, curthread);
LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
if (rval)
@ -380,6 +383,9 @@ _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
#endif
if (mtx_owned(m)) {
KASSERT((m->mtx_object.lo_flags & LO_RECURSABLE) != 0,
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
m->mtx_object.lo_name, file, line));
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
if (LOCK_LOG_TEST(&m->mtx_object, opts))