Module Name: src
Committed By: thorpej
Date: Wed Jan 1 21:09:12 UTC 2020
Modified Files:
src/sys/dev: clock_subr.h
src/sys/kern: init_main.c kern_todr.c
Log Message:
First steps towards properly serializing access to the TOD clock.
- Add a mutex around the TODR, and provide lock/unlock/lock-owned
functions to manipulate it.
- Rename inittodr() to todr_set_systime() and resettodr() to
todr_save_systime() to better reflect what they do. These functions
are intended to be called with the TODR lock held, which will allow
for a pattern like:
-> todr_lock()
-> todr_save_systime()
-> [do machine-dependent stuff to sleep/suspend]
-> [magically awaken]
-> todr_set_systime(...)
-> todr_unlock()
- Provide historically-named wrappers inittodr() and resettodr() that
do the dance of acquiring / releasing the lock around the actual
substance.
NOTE: resettodr()'s use of the TODR lock is currently disabled (and
todr_save_systime() does not assert it's held) until such time as
issues around shutdown / reboot under duress can be addressed.
To generate a diff of this commit:
cvs rdiff -u -r1.28 -r1.29 src/sys/dev/clock_subr.h
cvs rdiff -u -r1.514 -r1.515 src/sys/kern/init_main.c
cvs rdiff -u -r1.43 -r1.44 src/sys/kern/kern_todr.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/clock_subr.h
diff -u src/sys/dev/clock_subr.h:1.28 src/sys/dev/clock_subr.h:1.29
--- src/sys/dev/clock_subr.h:1.28 Wed Jan 1 19:24:03 2020
+++ src/sys/dev/clock_subr.h Wed Jan 1 21:09:11 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: clock_subr.h,v 1.28 2020/01/01 19:24:03 thorpej Exp $ */
+/* $NetBSD: clock_subr.h,v 1.29 2020/01/01 21:09:11 thorpej Exp $ */
/*-
- * Copyright (c) 1996 The NetBSD Foundation, Inc.
+ * Copyright (c) 1996, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -93,10 +93,13 @@ struct todr_chip_handle {
};
typedef struct todr_chip_handle *todr_chip_handle_t;
-/*
- * Machine-dependent function that machine-independent RTC drivers can
- * use to register their todr_chip_handle_t with inittodr()/resettodr().
- */
+void todr_init(void);
void todr_attach(todr_chip_handle_t);
+void todr_lock(void);
+void todr_unlock(void);
+bool todr_lock_owned(void);
+
+void todr_set_systime(time_t base);
+void todr_save_systime(void);
#endif /* _DEV_CLOCK_SUBR_H_ */
Index: src/sys/kern/init_main.c
diff -u src/sys/kern/init_main.c:1.514 src/sys/kern/init_main.c:1.515
--- src/sys/kern/init_main.c:1.514 Tue Dec 31 13:07:13 2019
+++ src/sys/kern/init_main.c Wed Jan 1 21:09:11 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: init_main.c,v 1.514 2019/12/31 13:07:13 ad Exp $ */
+/* $NetBSD: init_main.c,v 1.515 2020/01/01 21:09:11 thorpej Exp $ */
/*-
- * Copyright (c) 2008, 2009, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2008, 2009, 2019, The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -97,7 +97,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.514 2019/12/31 13:07:13 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: init_main.c,v 1.515 2020/01/01 21:09:11 thorpej Exp $");
#include "opt_ddb.h"
#include "opt_inet.h"
@@ -204,6 +204,8 @@ extern void *_binary_splash_image_end;
#include <sys/pax.h>
+#include <dev/clock_subr.h>
+
#include <secmodel/secmodel.h>
#include <ufs/ufs/quota.h>
@@ -298,6 +300,7 @@ main(void)
kernel_lock_init();
once_init();
+ todr_init();
mi_cpu_init();
kernconfig_lock_init();
Index: src/sys/kern/kern_todr.c
diff -u src/sys/kern/kern_todr.c:1.43 src/sys/kern/kern_todr.c:1.44
--- src/sys/kern/kern_todr.c:1.43 Wed Jan 1 19:24:03 2020
+++ src/sys/kern/kern_todr.c Wed Jan 1 21:09:11 2020
@@ -1,4 +1,33 @@
-/* $NetBSD: kern_todr.c,v 1.43 2020/01/01 19:24:03 thorpej Exp $ */
+/* $NetBSD: kern_todr.c,v 1.44 2020/01/01 21:09:11 thorpej Exp $ */
+
+/*-
+ * Copyright (c) 2020 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Jason R. Thorpe.
+ *
+ * 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.
+ */
/*
* Copyright (c) 1988 University of Utah.
@@ -41,7 +70,7 @@
#include "opt_todr.h"
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_todr.c,v 1.43 2020/01/01 19:24:03 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_todr.c,v 1.44 2020/01/01 21:09:11 thorpej Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -50,35 +79,98 @@ __KERNEL_RCSID(0, "$NetBSD: kern_todr.c,
#include <sys/timetc.h>
#include <sys/intr.h>
#include <sys/rndsource.h>
+#include <sys/mutex.h>
#include <dev/clock_subr.h> /* hmm.. this should probably move to sys */
static int todr_gettime(todr_chip_handle_t, struct timeval *);
static int todr_settime(todr_chip_handle_t, struct timeval *);
-static todr_chip_handle_t todr_handle = NULL;
+static kmutex_t todr_mutex;
+static todr_chip_handle_t todr_handle;
+static bool todr_initialized;
+
+/*
+ * todr_init:
+ * Initialize TOD clock data.
+ */
+void
+todr_init(void)
+{
+
+ mutex_init(&todr_mutex, MUTEX_DEFAULT, IPL_NONE);
+ todr_initialized = true;
+}
+
+/*
+ * todr_lock:
+ * Acquire the TODR lock.
+ */
+void
+todr_lock(void)
+{
+
+ mutex_enter(&todr_mutex);
+}
+
+/*
+ * todr_unlock:
+ * Release the TODR lock.
+ */
+void
+todr_unlock(void)
+{
+
+ mutex_exit(&todr_mutex);
+}
+
+/*
+ * todr_lock_owned:
+ * Return true if the current thread owns the TODR lock.
+ * This is to be used by diagnostic assertions only.
+ */
+bool
+todr_lock_owned(void)
+{
+
+ return mutex_owned(&todr_mutex) ? true : false;
+}
/*
- * Attach the clock device to todr_handle.
+ * todr_attach:
+ * Attach the clock device to todr_handle.
*/
void
todr_attach(todr_chip_handle_t todr)
{
+ /*
+ * todr_init() is called very early in main(), but this is
+ * here to catch a case where todr_attach() is called before
+ * main().
+ */
+ KASSERT(todr_initialized);
+
+ todr_lock();
if (todr_handle) {
+ todr_unlock();
printf("todr_attach: TOD already configured\n");
return;
}
todr_handle = todr;
+ todr_unlock();
}
static bool timeset = false;
/*
- * Set up the system's time, given a `reasonable' time value.
+ * todr_set_systime:
+ * Set up the system's time. The "base" argument is a best-guess
+ * close-enough value to use if the TOD clock is unavailable or
+ * contains garbage. Must be called with the TODR lock held.
*/
void
-inittodr(time_t base)
+todr_set_systime(time_t base)
{
bool badbase = false;
bool waszero = (base == 0);
@@ -87,6 +179,8 @@ inittodr(time_t base)
struct timespec ts;
struct timeval tv;
+ KASSERT(todr_lock_owned());
+
rnd_add_data(NULL, &base, sizeof(base), 0);
if (base < 5 * SECS_PER_COMMON_YEAR) {
@@ -180,17 +274,19 @@ inittodr(time_t base)
}
/*
- * Reset the TODR based on the time value; used when the TODR
- * has a preposterous value and also when the time is reset
- * by the stime system call. Also called when the TODR goes past
- * TODRZERO + 100*(SECS_PER_COMMON_YEAR+2*SECS_PER_DAY)
- * (e.g. on Jan 2 just after midnight) to wrap the TODR around.
+ * todr_save_systime:
+ * Save the current system time back to the TOD clock.
+ * Must be called with the TODR lock held.
*/
void
-resettodr(void)
+todr_save_systime(void)
{
struct timeval tv;
+#if notyet
+ KASSERT(todr_lock_owned());
+#endif
+
/*
* We might have been called by boot() due to a crash early
* on. Don't reset the clock chip if we don't know what time
@@ -209,6 +305,47 @@ resettodr(void)
printf("Cannot set TOD clock time\n");
}
+/*
+ * inittodr:
+ * Legacy wrapper around todr_set_systime().
+ */
+void
+inittodr(time_t base)
+{
+
+ todr_lock();
+ todr_set_systime(base);
+ todr_unlock();
+}
+
+/*
+ * resettodr:
+ * Legacy wrapper around todr_save_systime().
+ */
+void
+resettodr(void)
+{
+
+#if notyet
+ /*
+ * If we're shutting down, we don't want to get stuck in case
+ * someone was already fiddling with the TOD clock.
+ */
+ if (shutting_down) {
+ if (mutex_tryenter(&todr_mutex) == 0) {
+ printf("WARNING: Cannot set TOD clock time (busy)\n");
+ return;
+ }
+ } else {
+ todr_lock();
+ }
+#endif
+ todr_save_systime();
+#if notyet
+ todr_unlock();
+#endif
+}
+
#ifdef TODR_DEBUG
static void
todr_debug(const char *prefix, int rv, struct clock_ymdhms *dt,
