[src/trunk]: src/sys/external/bsd/drm2/include/linux Make Linux ww_mutex use ...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4064b97f3660
branches:  trunk
changeset: 330796:4064b97f3660
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue Jul 22 02:38:31 2014 +0000

description:
Make Linux ww_mutex use a spin lock inside, not an adaptive lock.

diffstat:

 sys/external/bsd/drm2/include/linux/ww_mutex.h |  8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diffs (22 lines):

diff -r 084f8d574fc4 -r 4064b97f3660 sys/external/bsd/drm2/include/linux/ww_mutex.h
--- a/sys/external/bsd/drm2/include/linux/ww_mutex.h    Tue Jul 22 02:21:50 2014 +0000
+++ b/sys/external/bsd/drm2/include/linux/ww_mutex.h    Tue Jul 22 02:38:31 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ww_mutex.h,v 1.1 2014/07/16 20:59:58 riastradh Exp $   */
+/*     $NetBSD: ww_mutex.h,v 1.2 2014/07/22 02:38:31 riastradh Exp $   */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -144,7 +144,11 @@
 ww_mutex_init(struct ww_mutex *mutex, struct ww_class *class)
 {
 
-       mutex_init(&mutex->wwm_lock, MUTEX_DEFAULT, IPL_NONE);
+       /*
+        * XXX Apparently Linux takes these with spin locks held.  That
+        * strikes me as a bad idea, but so it is...
+        */
+       mutex_init(&mutex->wwm_lock, MUTEX_DEFAULT, IPL_VM);
        mutex->wwm_state = WW_UNLOCKED;
        mutex->wwm_class = class;
        rb_tree_init(&mutex->wwm_waiters, &ww_acquire_ctx_rb_ops);