Author: mjg
Date: Sun Dec 31 00:34:29 2017
New Revision: 327395
URL: https://svnweb.freebsd.org/changeset/base/327395
Log:
mtx: deduplicate indefinite wait check in spinlocks and thread lock
Modified:
head/sys/kern/kern_mutex.c
Modified: head/sys/kern/kern_mutex.c
==============================================================================
--- head/sys/kern/kern_mutex.c Sun Dec 31 00:33:28 2017 (r327394)
+++ head/sys/kern/kern_mutex.c Sun Dec 31 00:34:29 2017 (r327395)
@@ -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
/* 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 @@ retry:
/* 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;
@@ -1229,6 +1200,31 @@ mutex_init(void)
mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
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
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