Introducing mutexes - cpu-owned spinning locks with spl semantics.

This is the MI (slightly inefficient and not MP safe) implementation.

deraadt@ ok Tested by many. (this and following commits)

3 files changed, 193 insertions, 1 deletions

diff --git a/sys/conf/files b/sys/conf/files
index 2afb58e8498..caf2d05e24d 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -1,4 +1,4 @@
-#	$OpenBSD: files,v 1.309 2004/07/15 12:10:44 henning Exp $
+#	$OpenBSD: files,v 1.310 2004/07/20 20:15:13 art Exp $
 #	$NetBSD: files,v 1.87 1996/05/19 17:17:50 jonathan Exp $
 
 #	@(#)files.newconf	7.5 (Berkeley) 5/10/93
@@ -581,6 +581,7 @@ file kern/subr_disk.c
 file kern/subr_evcount.c
 file kern/subr_extent.c
 file kern/subr_log.c
+file kern/subr_mutex.c
 file kern/subr_pool.c
 file kern/subr_prf.c
 file kern/subr_prof.c
diff --git a/sys/kern/subr_mutex.c b/sys/kern/subr_mutex.c
new file mode 100644
index 00000000000..d4f397466ae
--- /dev/null
+++ b/sys/kern/subr_mutex.c
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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/param.h>
+#include <sys/mutex.h>
+#include <sys/systm.h>
+
+#ifndef __HAVE_MUTEX
+
+/*
+ * Single processor systems don't need any mutexes, but they need the spl
+ * raising semantics of the mutexes.
+ */
+void
+mtx_init1(struct mutex *mtx, int wantipl)
+{
+	mtx->mtx_oldipl = 0;
+	mtx->mtx_wantipl = wantipl;
+	mtx->mtx_lock = 0;
+}
+
+void
+mtx_enter(struct mutex *mtx)
+{
+#define UGLY(lc, uc)	case MUTEX_IPL_##uc: mtx->mtx_oldipl = spl##lc(); break
+
+	switch (mtx->mtx_wantipl) {
+	UGLY(high, HIGH);
+	UGLY(statclock, STATCLOCK);
+#ifdef IPL_SCHED
+	UGLY(sched, SCHED);
+#endif
+	UGLY(clock, CLOCK);
+	UGLY(vm, VM);
+	UGLY(tty, TTY);
+	UGLY(net, NET);	
+	UGLY(bio, BIO);
+	UGLY(softnet, SOFTNET);
+	UGLY(softclock, SOFTCLOCK);
+	case MUTEX_IPL_NONE:
+		break;
+	default:
+		panic("mtx_enter: ipl not implemented");
+	}
+#undef UGLY
+
+	MUTEX_ASSERT_UNLOCKED(mtx);
+	mtx->mtx_lock = 1;
+}
+
+void
+mtx_leave(struct mutex *mtx)
+{
+	MUTEX_ASSERT_LOCKED(mtx);
+	mtx->mtx_lock = 0;
+	if (mtx->mtx_wantipl != MUTEX_IPL_NONE)
+		splx(mtx->mtx_oldipl);
+}
+
+#endif
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
new file mode 100644
index 00000000000..51e08d702d0
--- /dev/null
+++ b/sys/sys/mutex.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2004 Artur Grabowski <art@openbsd.org>
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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 _SYS_MUTEX_H_
+#define _SYS_MUTEX_H_
+
+/*
+ * A mutex is:
+ *  - owned by a cpu.
+ *  - non-recursive.
+ *  - spinning.
+ *  - not providing mutual exclusion between processes, only cpus.
+ *  - providing interrupt blocking when necessary.
+ *
+ * Different mutexes can be nested, but not interleaved. This is ok:
+ * "mtx_enter(foo); mtx_enter(bar); mtx_leave(bar); mtx_leave(foo);"
+ * This is _not_ ok:
+ * "mtx_enter(foo); mtx_enter(bar); mtx_leave(foo); mtx_leave(bar);"
+ */
+
+#ifdef __HAVE_MUTEX
+#include <machine/mutex.h>
+#else
+
+/*
+ * Simple non-mp implementation.
+ */
+struct mutex {
+	int mtx_lock;
+	int mtx_wantipl;
+	int mtx_oldipl;
+};
+
+/*
+ * Since the alpha IPL levels are so messed up, we have to do magic to get
+ * this right.
+ */
+#define MUTEX_IPL(ipl) MUTEX_##ipl
+#define MUTEX_IPL_NONE		0
+#define MUTEX_IPL_SOFTSERIAL	1
+#define MUTEX_IPL_SOFTCLOCK	2
+#define MUTEX_IPL_SOFTNET	3
+#define MUTEX_IPL_NET		4
+#define MUTEX_IPL_BIO		5
+#define MUTEX_IPL_VM		6
+#define MUTEX_IPL_TTY		7
+#define MUTEX_IPL_SERIAL	8
+#define MUTEX_IPL_AUDIO		9
+#define MUTEX_IPL_CLOCK		10
+#define MUTEX_IPL_STATCLOCK	11
+#define MUTEX_IPL_SCHED		12
+#define MUTEX_IPL_HIGH		13
+
+void mtx_init1(struct mutex *, int);
+#define mtx_init(mtx, ipl) mtx_init1(mtx, MUTEX_##ipl)
+
+#define MUTEX_INITIALIZER(ipl) { 0, MUTEX_##ipl, 0 }
+
+#ifdef DIAGNOSTIC
+#define MUTEX_ASSERT_LOCKED(mtx) do {					\
+	if ((mtx)->mtx_lock == 0)					\
+		panic("mutex %p not held in %s\n", (mtx), __func__);	\
+} while (0)
+
+#define MUTEX_ASSERT_UNLOCKED(mtx) do {					\
+	if ((mtx)->mtx_lock != 0)					\
+		panic("mutex %p held in %s\n", (mtx), __func__);	\
+} while (0)
+#else
+#define MUTEX_ASSERT_LOCKED(mtx) do { } while (0)
+#define MUTEX_ASSERT_UNLOCKED(mtx) do { } while (0)
+#endif
+
+#define MUTEX_OLDIPL(mtx)	(mtx)->mtx_oldipl
+
+#endif
+
+/*
+ * Some architectures need to do magic for the ipl, so they need a macro.
+ */
+#ifndef mtx_init
+void mtx_init(struct mutex *, int);
+#endif
+void mtx_enter(struct mutex *);
+void mtx_leave(struct mutex *);
+
+#endif