[src/trunk]: src/sys/external/bsd/drm2/include/drm Reimplement task barrier w...

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

details:   https://anonhg.NetBSD.org/src/rev/0af096e7652b
branches:  trunk
changeset: 1028407:0af096e7652b
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 10:58:29 2021 +0000

description:
Reimplement task barrier without semaphores.

diffstat:

 sys/external/bsd/drm2/include/drm/task_barrier.h |  120 +++++++++++++++++++++++
 1 files changed, 120 insertions(+), 0 deletions(-)

diffs (124 lines):

diff -r c5f23927e621 -r 0af096e7652b sys/external/bsd/drm2/include/drm/task_barrier.h
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/external/bsd/drm2/include/drm/task_barrier.h  Sun Dec 19 10:58:29 2021 +0000
@@ -0,0 +1,120 @@
+/*     $NetBSD: task_barrier.h,v 1.1 2021/12/19 10:58:29 riastradh Exp $       */
+
+/*-
+ * Copyright (c) 2020 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * 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
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``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.
+ */
+
+#ifndef _DRM_TASK_BARRIER_H_
+#define _DRM_TASK_BARRIER_H_
+
+#include <sys/condvar.h>
+#include <sys/mutex.h>
+
+struct task_barrier {
+       kmutex_t        tb_lock;
+       kcondvar_t      tb_cv;
+       unsigned        tb_cur;
+       unsigned        tb_gen;
+       unsigned        tb_max;
+};
+
+static inline void
+task_barrier_init(struct task_barrier *tb)
+{
+
+       mutex_init(&tb->tb_lock, MUTEX_DEFAULT, IPL_VM);
+       cv_init(&tb->tb_cv, "taskbar");
+       tb->tb_cur = 0;
+       tb->tb_gen = 0;
+       tb->tb_max = 0;
+}
+
+static inline void
+task_barrier_destroy(struct task_barrier *tb)
+{
+
+       KASSERT(tb->tb_cur == 0);
+       cv_destroy(&tb->tb_cv);
+       mutex_destroy(&tb->tb_lock);
+}
+
+static inline void
+task_barrier_add_task(struct task_barrier *tb)
+{
+
+       tb->tb_max++;
+}
+
+static inline void
+task_barrier_rem_task(struct task_barrier *tb)
+{
+
+       tb->tb_max--;
+}
+
+static inline void
+task_barrier_enter(struct task_barrier *tb)
+{
+
+       mutex_enter(&tb->tb_lock);
+       KASSERT(tb->tb_cur < tb->tb_max);
+       if (++tb->tb_cur < tb->tb_max) {
+               unsigned gen = tb->tb_gen;
+               do {
+                       cv_wait(&tb->tb_cv, &tb->tb_lock);
+               } while (gen == tb->tb_gen);
+       } else {
+               tb->tb_gen++;
+               cv_broadcast(&tb->tb_cv);
+       }
+       mutex_exit(&tb->tb_lock);
+}
+
+static inline void
+task_barrier_exit(struct task_barrier *tb)
+{
+
+       mutex_enter(&tb->tb_lock);
+       KASSERT(tb->tb_cur > 0);
+       if (--tb->tb_cur > 0) {
+               unsigned gen = tb->tb_gen;
+               do {
+                       cv_wait(&tb->tb_cv, &tb->tb_lock);
+               } while (gen == tb->tb_gen);
+       } else {
+               tb->tb_gen++;
+               cv_broadcast(&tb->tb_cv);
+       }
+}
+
+static inline void
+task_barrier_full(struct task_barrier *tb)
+{
+
+       task_barrier_enter(tb);
+       task_barrier_exit(tb);
+}
+
+#endif /* _DRM_TASK_BARRIER_H_ */