Tue Jul 22 02:38:31 2014 UTC ()
Make Linux ww_mutex use a spin lock inside, not an adaptive lock.


(riastradh)
diff -r1.1 -r1.2 src/sys/external/bsd/drm2/include/linux/ww_mutex.h
cvs diff -r1.1 -r1.2 src/sys/external/bsd/drm2/include/linux/ww_mutex.h (expand / switch to unified diff)

--- src/sys/external/bsd/drm2/include/linux/ww_mutex.h 2014/07/16 20:59:58 1.1
+++ src/sys/external/bsd/drm2/include/linux/ww_mutex.h 2014/07/22 02:38:31 1.2
@@ -1,14 +1,14 @@ @@ -1,14 +1,14 @@
1/* $NetBSD: ww_mutex.h,v 1.1 2014/07/16 20:59:58 riastradh Exp $ */ 1/* $NetBSD: ww_mutex.h,v 1.2 2014/07/22 02:38:31 riastradh Exp $ */
2 2
3/*- 3/*-
4 * Copyright (c) 2014 The NetBSD Foundation, Inc. 4 * Copyright (c) 2014 The NetBSD Foundation, Inc.
5 * All rights reserved. 5 * All rights reserved.
6 * 6 *
7 * This code is derived from software contributed to The NetBSD Foundation 7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell. 8 * by Taylor R. Campbell.
9 * 9 *
10 * Redistribution and use in source and binary forms, with or without 10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions 11 * modification, are permitted provided that the following conditions
12 * are met: 12 * are met:
13 * 1. Redistributions of source code must retain the above copyright 13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer. 14 * notice, this list of conditions and the following disclaimer.
@@ -134,27 +134,31 @@ struct ww_mutex { @@ -134,27 +134,31 @@ struct ww_mutex {
134 union { 134 union {
135 struct lwp *owner; 135 struct lwp *owner;
136 struct ww_acquire_ctx *ctx; 136 struct ww_acquire_ctx *ctx;
137 } wwm_u; 137 } wwm_u;
138 struct ww_class *wwm_class; 138 struct ww_class *wwm_class;
139 struct rb_tree wwm_waiters; 139 struct rb_tree wwm_waiters;
140 kcondvar_t wwm_cv; 140 kcondvar_t wwm_cv;
141}; 141};
142 142
143static inline void 143static inline void
144ww_mutex_init(struct ww_mutex *mutex, struct ww_class *class) 144ww_mutex_init(struct ww_mutex *mutex, struct ww_class *class)
145{ 145{
146 146
147 mutex_init(&mutex->wwm_lock, MUTEX_DEFAULT, IPL_NONE); 147 /*
 148 * XXX Apparently Linux takes these with spin locks held. That
 149 * strikes me as a bad idea, but so it is...
 150 */
 151 mutex_init(&mutex->wwm_lock, MUTEX_DEFAULT, IPL_VM);
148 mutex->wwm_state = WW_UNLOCKED; 152 mutex->wwm_state = WW_UNLOCKED;
149 mutex->wwm_class = class; 153 mutex->wwm_class = class;
150 rb_tree_init(&mutex->wwm_waiters, &ww_acquire_ctx_rb_ops); 154 rb_tree_init(&mutex->wwm_waiters, &ww_acquire_ctx_rb_ops);
151 cv_init(&mutex->wwm_cv, "linuxwwm"); 155 cv_init(&mutex->wwm_cv, "linuxwwm");
152} 156}
153 157
154static inline void 158static inline void
155ww_mutex_destroy(struct ww_mutex *mutex) 159ww_mutex_destroy(struct ww_mutex *mutex)
156{ 160{
157 161
158 cv_destroy(&mutex->wwm_cv); 162 cv_destroy(&mutex->wwm_cv);
159#if 0 163#if 0
160 rb_tree_destroy(&mutex->wwm_waiters, &ww_acquire_ctx_rb_ops); 164 rb_tree_destroy(&mutex->wwm_waiters, &ww_acquire_ctx_rb_ops);