 @@ -1,17 +1,17 @@
-/*	$NetBSD: kern_lock.c,v 1.164 2019/12/03 15:20:59 riastradh Exp $	*/
+/*	$NetBSD: kern_lock.c,v 1.165 2020/01/17 20:26:22 ad Exp $	*/
 /*-
- * Copyright (c) 2002, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
+ * Copyright (c) 2002, 2006, 2007, 2008, 2009, 2020 The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
  * NASA Ames Research Center, and by Andrew Doran.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
 @@ -21,27 +21,27 @@
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.164 2019/12/03 15:20:59 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.165 2020/01/17 20:26:22 ad Exp $");
 #include <sys/param.h>
 #include <sys/proc.h>
 #include <sys/lock.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
 #include <sys/lockdebug.h>
 #include <sys/cpu.h>
 #include <sys/syslog.h>
 #include <sys/atomic.h>
 #include <sys/lwp.h>
 #include <sys/pserialize.h>
 @@ -154,120 +154,134 @@ _kernel_lock_dump(const volatile void *j
 	    ci->ci_biglock_count, (long)ci->ci_biglock_wanted);
+}
 /*
  * Acquire 'nlocks' holds on the kernel lock.
  */
 void
 _kernel_lock(int nlocks)
+{
 	struct cpu_info *ci;
 	LOCKSTAT_TIMER(spintime);
 	LOCKSTAT_FLAG(lsflag);
 	struct lwp *owant;
-	u_int spins;
+	u_int count;
 #ifdef LOCKDEBUG
 	u_int spins = 0;
 #endif
 	int s;
 	struct lwp *l = curlwp;
 	_KERNEL_LOCK_ASSERT(nlocks > 0);
 	s = splvm();
 	ci = curcpu();
 	if (ci->ci_biglock_count != 0) {
 		_KERNEL_LOCK_ASSERT(__SIMPLELOCK_LOCKED_P(kernel_lock));
 		ci->ci_biglock_count += nlocks;
 		l->l_blcnt += nlocks;
 		splx(s);
 		return;
+	}
 	_KERNEL_LOCK_ASSERT(l->l_blcnt == 0);
 	LOCKDEBUG_WANTLOCK(kernel_lock_dodebug, kernel_lock, RETURN_ADDRESS,
 );
-	if (__cpu_simple_lock_try(kernel_lock)) {
+	if (__predict_true(__cpu_simple_lock_try(kernel_lock))) {
 		ci->ci_biglock_count = nlocks;
 		l->l_blcnt = nlocks;
 		LOCKDEBUG_LOCKED(kernel_lock_dodebug, kernel_lock, NULL,
 		    RETURN_ADDRESS, 0);
 		splx(s);
 		return;
+	}
 	/*
 	 * To remove the ordering constraint between adaptive mutexes
 	 * and kernel_lock we must make it appear as if this thread is
 	 * blocking.  For non-interlocked mutex release, a store fence
 	 * is required to ensure that the result of any mutex_exit()
 	 * by the current LWP becomes visible on the bus before the set
 	 * of ci->ci_biglock_wanted becomes visible.
+	 *
 	 * However, we won't set ci_biglock_wanted until we've spun for
 	 * a bit, as we don't want to make any lock waiters in rw_oncpu()
 	 * or mutex_oncpu() block prematurely.
 	 */
 	membar_producer();
 	owant = ci->ci_biglock_wanted;
 	ci->ci_biglock_wanted = l;
 	/*
 	 * Spin until we acquire the lock.  Once we have it, record the
 	 * time spent with lockstat.
 	 */
 	LOCKSTAT_ENTER(lsflag);
 	LOCKSTAT_START_TIMER(lsflag, spintime);
-	spins = 0;
+	count = SPINLOCK_BACKOFF_MIN;
 	do {
 		splx(s);
 		while (__SIMPLELOCK_LOCKED_P(kernel_lock)) {
 #ifdef LOCKDEBUG
 			if (SPINLOCK_SPINOUT(spins)) {
 				extern int start_init_exec;
 				if (!start_init_exec)
 					_KERNEL_LOCK_ABORT("spinout");
+			}
-			SPINLOCK_BACKOFF_HOOK;
+#endif
-			SPINLOCK_SPIN_HOOK;
+			SPINLOCK_BACKOFF(count);
 			if (count == SPINLOCK_BACKOFF_MAX) {
 				/* Ok, waiting for real. */
 				ci->ci_biglock_wanted = l;
+			}
+		}
 		s = splvm();
 	} while (!__cpu_simple_lock_try(kernel_lock));
 	ci->ci_biglock_count = nlocks;
 	l->l_blcnt = nlocks;
 	splx(s);
 	LOCKSTAT_STOP_TIMER(lsflag, spintime);
 	LOCKDEBUG_LOCKED(kernel_lock_dodebug, kernel_lock, NULL,
 	    RETURN_ADDRESS, 0);
 	if (owant == NULL) {
 		LOCKSTAT_EVENT_RA(lsflag, kernel_lock,
 		    LB_KERNEL_LOCK | LB_SPIN, 1, spintime, RETURN_ADDRESS);
+	}
 	LOCKSTAT_EXIT(lsflag);
 	splx(s);
 	/*
 	 * Now that we have kernel_lock, reset ci_biglock_wanted.  This
 	 * store must be unbuffered (immediately visible on the bus) in
 	 * order for non-interlocked mutex release to work correctly.
 	 * It must be visible before a mutex_exit() can execute on this
 	 * processor.
+	 *
 	 * Note: only where CAS is available in hardware will this be
 	 * an unbuffered write, but non-interlocked release cannot be
 	 * done on CPUs without CAS in hardware.
 	 */
 	(void)atomic_swap_ptr(&ci->ci_biglock_wanted, owant);
 	/*
 	 * Issue a memory barrier as we have acquired a lock.  This also
 	 * prevents stores from a following mutex_exit() being reordered
 	 * to occur before our store to ci_biglock_wanted above.
 	 */
 #ifndef __HAVE_ATOMIC_AS_MEMBAR
 	membar_enter();
 #endif
+}
 /*
  * Release 'nlocks' holds on the kernel lock.  If 'nlocks' is zero, release
  * all holds.
  */
 void
 _kernel_unlock(int nlocks, int *countp)
+{
 	struct cpu_info *ci;
 	u_int olocks;
 	int s;
 	struct lwp *l = curlwp;