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mtx: deduplicate indefinite wait check in spinlocks and thread lock

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This commit is contained in:
mjg 2017-12-31 00:34:29 +00:00
parent a59af230d8
commit c7b2a94e2a
1 changed files with 31 additions and 35 deletions
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66
sys/kern/kern_mutex.c
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@ -170,6 +170,8 @@ LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
struct mtx blocked_lock;
struct mtx __exclusive_cache_line Giant;
static void _mtx_lock_indefinite_check(struct mtx *, struct lock_delay_arg *);
void
assert_mtx(const struct lock_object *lock, int what)
{
@ -674,25 +676,6 @@ __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v)
#endif
}
static void
_mtx_lock_spin_failed(struct mtx *m)
{
struct thread *td;
td = mtx_owner(m);
/* If the mutex is unlocked, try again. */
if (td == NULL)
return;
printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
m, m->lock_object.lo_name, td, td->td_tid);
#ifdef WITNESS
witness_display_spinlock(&m->lock_object, td, printf);
#endif
panic("spin lock held too long");
}
#ifdef SMP
/*
* _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
@ -764,16 +747,10 @@ _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v)
/* Give interrupts a chance while we spin. */
spinlock_exit();
do {
if (lda.spin_cnt < 10000000) {
if (__predict_true(lda.spin_cnt < 10000000)) {
lock_delay(&lda);
} else {
lda.spin_cnt++;
if (lda.spin_cnt < 60000000 || kdb_active ||
panicstr != NULL)
DELAY(1);
else
_mtx_lock_spin_failed(m);
cpu_spinwait();
_mtx_lock_indefinite_check(m, &lda);
}
v = MTX_READ_VALUE(m);
} while (v != MTX_UNOWNED);
@ -931,16 +908,10 @@ thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
/* Give interrupts a chance while we spin. */
spinlock_exit();
do {
if (lda.spin_cnt < 10000000) {
if (__predict_true(lda.spin_cnt < 10000000)) {
lock_delay(&lda);
} else {
lda.spin_cnt++;
if (lda.spin_cnt < 60000000 ||
kdb_active || panicstr != NULL)
DELAY(1);
else
_mtx_lock_spin_failed(m);
cpu_spinwait();
_mtx_lock_indefinite_check(m, &lda);
}
if (m != td->td_lock)
goto retry;
@ -1231,6 +1202,31 @@ mutex_init(void)
mtx_lock(&Giant);
}
static void __noinline
_mtx_lock_indefinite_check(struct mtx *m, struct lock_delay_arg *ldap)
{
struct thread *td;
ldap->spin_cnt++;
if (ldap->spin_cnt < 60000000 || kdb_active || panicstr != NULL)
DELAY(1);
else {
td = mtx_owner(m);
/* If the mutex is unlocked, try again. */
if (td == NULL)
return;
printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
m, m->lock_object.lo_name, td, td->td_tid);
#ifdef WITNESS
witness_display_spinlock(&m->lock_object, td, printf);
#endif
panic("spin lock held too long");
}
cpu_spinwait();
}
#ifdef DDB
void
db_show_mtx(const struct lock_object *lock)