APM was calling the suspend process from a timeout. This meant that

other timeouts could not happen while suspending, including timeouts
for things like msleep.  This caused the system to hang on suspend
when the cbb was enabled, since its suspend path powered down the
socket which used a timeout to wait for it to be done.

APM now creates a thread when it is enabled, and deletes the thread
when it is disabled.  This thread takes the place of the timeout by
doing its polling every ~.9s.  When the thread is disabled, it will
wakeup early, otherwise it times out and polls the varius things the
old timeout polled (APM events, suspend delays, etc).

This makes my Sony VAIO 505TS suspend/resume correctly when APM is
enabled (ACPI is black listed on my 505TS).

This will likely fix other problems with the suspend path where
drivers would sleep with msleep and/or do other timeouts.  Maybe
there's some special case code that would use DELAY while suspending
and msleep otherwise that can be revisited and removed.

This was also tested by glebius@, who pointed out that in the patch I
sent him, I'd forgotten apm_saver.c

MFC After: 3 weeks

2 files changed, 42 insertions, 27 deletions

diff --git a/sys/i386/bios/apm.c b/sys/i386/bios/apm.c
index b9b446d..4e3dba3 100644
--- a/sys/i386/bios/apm.c
+++ b/sys/i386/bios/apm.c
@@ -23,10 +23,14 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/bus.h>
 #include <sys/conf.h>
+#include <sys/condvar.h>
 #include <sys/eventhandler.h>
 #include <sys/fcntl.h>
 #include <sys/kernel.h>
+#include <sys/kthread.h>
+#include <sys/lock.h>
 #include <sys/module.h>
+#include <sys/mutex.h>
 #include <sys/poll.h>
 #include <sys/power.h>
 #include <sys/reboot.h>
@@ -98,10 +102,6 @@ static struct apmhook	*hook[NAPM_HOOK];		/* XXX */
 /* Map version number to integer (keeps ordering of version numbers) */
 #define INTVERSION(major, minor)	((major)*100 + (minor))
 
-static struct callout_handle apm_timeout_ch = 
-    CALLOUT_HANDLE_INITIALIZER(&apm_timeout_ch);
-
-static timeout_t apm_timeout;
 static d_open_t apmopen;
 static d_close_t apmclose;
 static d_write_t apmwrite;
@@ -728,31 +728,32 @@ apm_cpu_busy(void)
 
 
 /*
- * APM timeout routine:
+ * APM thread loop.
  *
- * This routine is automatically called by timer once per second.
+ * This routine wakes up from time to time to deal with delaying the
+ * suspend of the system, or other events.
  */
-
 static void
-apm_timeout(void *dummy)
+apm_event_thread(void *arg)
 {
 	struct apm_softc *sc = &apm_softc;
 
-	if (apm_op_inprog)
-		apm_lastreq_notify();
-
-	if (sc->standbys && sc->standby_countdown-- <= 0)
-		apm_do_standby();
-
-	if (sc->suspends && sc->suspend_countdown-- <= 0)
-		apm_do_suspend();
-
-	if (!sc->bios_busy)
-		apm_processevent();
-
-	if (sc->active == 1)
-		/* Run slightly more oftan than 1 Hz */
-		apm_timeout_ch = timeout(apm_timeout, NULL, hz - 1);
+	sc->running = 1;
+	while (sc->active) {
+		if (apm_op_inprog)
+			apm_lastreq_notify();
+		if (sc->standbys && sc->standby_countdown-- <= 0)
+			apm_do_standby();
+		if (sc->suspends && sc->suspend_countdown-- <= 0)
+			apm_do_suspend();
+		if (!sc->bios_busy)
+			apm_processevent();
+		mtx_lock(&sc->mtx);
+		cv_timedwait(&sc->cv, &sc->mtx, 10 * hz / 9);
+		mtx_unlock(&sc->mtx);
+	}
+	sc->running = 0;
+	kthread_exit(0);
 }
 
 /* enable APM BIOS */
@@ -766,8 +767,11 @@ apm_event_enable(void)
 	if (sc == NULL || sc->initialized == 0)
 		return;
 
+	/* Start the thread */
 	sc->active = 1;
-	apm_timeout(sc);
+	if (kthread_create(apm_event_thread, sc, &sc->event_thread, 0, 0,
+	    "apm worker"))
+		panic("Cannot create apm worker thread");
 
 	return;
 }
@@ -783,9 +787,14 @@ apm_event_disable(void)
 	if (sc == NULL || sc->initialized == 0)
 		return;
 
-	untimeout(apm_timeout, NULL, apm_timeout_ch);
+	mtx_lock(&sc->mtx);
 	sc->active = 0;
-
+	while (sc->running) {
+		cv_broadcast(&sc->cv);
+		msleep(sc->event_thread, &sc->mtx, PWAIT, "apmdie", 0);
+	}
+	mtx_unlock(&sc->mtx);
+	sc->event_thread = NULL;
 	return;
 }
 
@@ -1132,6 +1141,8 @@ apm_attach(device_t dev)
 #ifdef PC98
 	int			rid;
 #endif
+	mtx_init(&sc->mtx, device_get_nameunit(dev), "apm", MTX_DEF);
+	cv_init(&sc->cv, "cbb cv");
 
 	if (device_get_flags(dev) & 0x20)
 		statclock_disable = 1;
@@ -1223,6 +1234,7 @@ apm_attach(device_t dev)
 
 	sc->initialized = 1;
 	sc->suspending = 0;
+	sc->running = 0;
 
 	make_dev(&apm_cdevsw, 0, 0, 5, 0664, "apm");
 	make_dev(&apm_cdevsw, 8, 0, 5, 0660, "apmctl");
diff --git a/sys/i386/bios/apm.h b/sys/i386/bios/apm.h
index ce87c54..2b20e61 100644
--- a/sys/i386/bios/apm.h
+++ b/sys/i386/bios/apm.h
@@ -29,7 +29,10 @@ struct apm_softc {
 	bus_space_handle_t	sc_ioh;
 	struct resource 	*sc_res;
 #endif
-	int	initialized, active, bios_busy;
+	struct mtx	mtx;
+	struct cv	cv;
+	struct proc	*event_thread;
+	int	initialized, active, running, bios_busy;
 	int	always_halt_cpu, slow_idle_cpu;
 	int	disabled, disengaged;
 	int	suspending;