Disable suspend when we're shutting down. This solves the "tell FreeBSD

to shut down; close laptop lid" scenario which otherwise tended to end
with a laptop overheating or the battery dying.

The implementation uses a new sysctl, kern.suspend_blocked; init(8) sets
this while rc.suspend runs, and the ACPI sleep code ignores requests while
the sysctl is set.

Discussed on:	freebsd-acpi (35 emails)
MFC after:	1 week

4 files changed, 24 insertions, 2 deletions

diff --git a/sbin/init/init.c b/sbin/init/init.c
index 5ab3527c073d..edc38e66ea3e 100644
--- a/sbin/init/init.c
+++ b/sbin/init/init.c
@@ -1487,6 +1487,15 @@ static state_func_t
 death(void)
 {
 	session_t *sp;
+	int block, blocked;
+	size_t len;
+
+	/* Temporarily block suspend. */
+	len = sizeof(blocked);
+	block = 1;
+	if (sysctlbyname("kern.suspend_blocked", &blocked, &len,
+	    &block, sizeof(block)) == -1)
+		blocked = 0;
 
 	/*
 	 * Also revoke the TTY here.  Because runshutdown() may reopen
@@ -1503,6 +1512,11 @@ death(void)
 	/* Try to run the rc.shutdown script within a period of time */
 	runshutdown();
 
+	/* Unblock suspend if we blocked it. */
+	if (!blocked)
+		sysctlbyname("kern.suspend_blocked", NULL, NULL,
+		    &blocked, sizeof(blocked));
+
 	return (state_func_t) death_single;
 }
 
diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index 92f1292f0258..0593235c97df 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -2574,8 +2574,11 @@ acpi_ReqSleepState(struct acpi_softc *sc, int state)
     if (!acpi_sleep_states[state])
 	return (EOPNOTSUPP);
 
-    /* If a suspend request is already in progress, just return. */
-    if (sc->acpi_next_sstate != 0) {
+    /*
+     * If a reboot/shutdown/suspend request is already in progress or
+     * suspend is blocked due to an upcoming shutdown, just return.
+     */
+    if (rebooting || sc->acpi_next_sstate != 0 || suspend_blocked) {
 	return (0);
     }
 
diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index 29ea6931cad9..87e7d6388a71 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -137,6 +137,10 @@ static int show_busybufs = 1;
 SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
 	&show_busybufs, 0, "");
 
+int suspend_blocked = 0;
+SYSCTL_INT(_kern, OID_AUTO, suspend_blocked, CTLFLAG_RW,
+	&suspend_blocked, 0, "Block suspend due to a pending shutdown");
+
 /*
  * Variable panicstr contains argument to first call to panic; used as flag
  * to indicate that the kernel has already called panic.
diff --git a/sys/sys/systm.h b/sys/sys/systm.h
index 592112a0c860..6c688028d83e 100644
--- a/sys/sys/systm.h
+++ b/sys/sys/systm.h
@@ -46,6 +46,7 @@
 #include <sys/stdint.h>		/* for people using printf mainly */
 
 extern int cold;		/* nonzero if we are doing a cold boot */
+extern int suspend_blocked;	/* block suspend due to pending shutdown */
 extern int rebooting;		/* kern_reboot() has been called. */
 extern const char *panicstr;	/* panic message */
 extern char version[];		/* system version */