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add defines to control whether or not mutex operations are skipped

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after we have panic'd.  no functional change.
This commit is contained in:
chs 2018-02-25 18:54:29 +00:00
parent 3084abc1e1
commit e5440b91e0
1 changed files with 15 additions and 2 deletions
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17
sys/kern/kern_mutex.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_mutex.c,v 1.72 2018/02/06 07:46:24 ozaki-r Exp $ */
/* $NetBSD: kern_mutex.c,v 1.73 2018/02/25 18:54:29 chs Exp $ */
/*-
* Copyright (c) 2002, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@ -40,7 +40,7 @@
#define __MUTEX_PRIVATE
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_mutex.c,v 1.72 2018/02/06 07:46:24 ozaki-r Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_mutex.c,v 1.73 2018/02/25 18:54:29 chs Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
@ -60,6 +60,9 @@ __KERNEL_RCSID(0, "$NetBSD: kern_mutex.c,v 1.72 2018/02/06 07:46:24 ozaki-r Exp
#include <machine/lock.h>
#define MUTEX_PANIC_SKIP_SPIN 1
#define MUTEX_PANIC_SKIP_ADAPTIVE 1
/*
* When not running a debug kernel, spin mutexes are not much
* more than an splraiseipl() and splx() pair.
@ -489,8 +492,10 @@ mutex_vector_enter(kmutex_t *mtx)
* to reduce cache line ping-ponging between CPUs.
*/
do {
#if MUTEX_PANIC_SKIP_SPIN
if (panicstr != NULL)
break;
#endif
while (MUTEX_SPINBIT_LOCKED_P(mtx)) {
SPINLOCK_BACKOFF(count);
#ifdef LOCKDEBUG
@ -547,10 +552,12 @@ mutex_vector_enter(kmutex_t *mtx)
owner = mtx->mtx_owner;
continue;
}
#if MUTEX_PANIC_SKIP_ADAPTIVE
if (__predict_false(panicstr != NULL)) {
KPREEMPT_ENABLE(curlwp);
return;
}
#endif
if (__predict_false(MUTEX_OWNER(owner) == curthread)) {
MUTEX_ABORT(mtx, "locking against myself");
}
@ -726,8 +733,10 @@ mutex_vector_exit(kmutex_t *mtx)
if (MUTEX_SPIN_P(mtx)) {
#ifdef FULL
if (__predict_false(!MUTEX_SPINBIT_LOCKED_P(mtx))) {
#if MUTEX_PANIC_SKIP_SPIN
if (panicstr != NULL)
return;
#endif
MUTEX_ABORT(mtx, "exiting unheld spin mutex");
}
MUTEX_UNLOCKED(mtx);
@ -737,11 +746,13 @@ mutex_vector_exit(kmutex_t *mtx)
return;
}
#ifdef MUTEX_PANIC_SKIP_ADAPTIVE
if (__predict_false((uintptr_t)panicstr | cold)) {
MUTEX_UNLOCKED(mtx);
MUTEX_RELEASE(mtx);
return;
}
#endif
curthread = (uintptr_t)curlwp;
MUTEX_DASSERT(mtx, curthread != 0);
@ -932,8 +943,10 @@ mutex_spin_retry(kmutex_t *mtx)
* to reduce cache line ping-ponging between CPUs.
*/
do {
#if MUTEX_PANIC_SKIP_SPIN
if (panicstr != NULL)
break;
#endif
while (MUTEX_SPINBIT_LOCKED_P(mtx)) {
SPINLOCK_BACKOFF(count);
#ifdef LOCKDEBUG