Revert r263754, re-adding support for hw.bus.devctl_disable. Breaking

old devd's and thus hosts that get IP addresses from DHCP was too much
of a POLA violation.

The sysctl may be removed again after r263758 has been merged to at
least stable/9 and stable/10, and releases have been cut from those
branches.

Discussed with:	mjg
Reported by:	theraven, rwatson

1 files changed, 37 insertions, 3 deletions

diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index dbe88b2..53b10ec 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -355,6 +355,13 @@ device_sysctl_fini(device_t dev)
  * tested since 3.4 or 2.2.8!
  */
 
+/* Deprecated way to adjust queue length */
+static int sysctl_devctl_disable(SYSCTL_HANDLER_ARGS);
+/* XXX Need to support old-style tunable hw.bus.devctl_disable" */
+SYSCTL_PROC(_hw_bus, OID_AUTO, devctl_disable, CTLTYPE_INT | CTLFLAG_RW |
+    CTLFLAG_MPSAFE, NULL, 0, sysctl_devctl_disable, "I",
+    "devctl disable -- deprecated");
+
 #define DEVCTL_DEFAULT_QUEUE_LEN 1000
 static int sysctl_devctl_queue(SYSCTL_HANDLER_ARGS);
 static int devctl_queue_length = DEVCTL_DEFAULT_QUEUE_LEN;
@@ -685,9 +692,9 @@ devctl_notify(const char *system, const char *subsystem, const char *type,
  * Common routine that tries to make sending messages as easy as possible.
  * We allocate memory for the data, copy strings into that, but do not
  * free it unless there's an error.  The dequeue part of the driver should
- * free the data.  We don't send data when queue length is 0.  We do send
- * data, even when we have no listeners, because we wish to avoid races
- * relating to startup and restart of listening applications.
+ * free the data.  We don't send data when the device is disabled.  We do
+ * send data, even when we have no listeners, because we wish to avoid
+ * races relating to startup and restart of listening applications.
  *
  * devaddq is designed to string together the type of event, with the
  * object of that event, plus the plug and play info and location info
@@ -779,6 +786,33 @@ devnomatch(device_t dev)
 }
 
 static int
+sysctl_devctl_disable(SYSCTL_HANDLER_ARGS)
+{
+	struct dev_event_info *n1;
+	int dis, error;
+
+	dis = devctl_queue_length == 0;
+	error = sysctl_handle_int(oidp, &dis, 0, req);
+	if (error || !req->newptr)
+		return (error);
+	mtx_lock(&devsoftc.mtx);
+	if (dis) {
+		while (!TAILQ_EMPTY(&devsoftc.devq)) {
+			n1 = TAILQ_FIRST(&devsoftc.devq);
+			TAILQ_REMOVE(&devsoftc.devq, n1, dei_link);
+			free(n1->dei_data, M_BUS);
+			free(n1, M_BUS);
+		}
+		devsoftc.queued = 0;
+		devctl_queue_length = 0;
+	} else {
+		devctl_queue_length = DEVCTL_DEFAULT_QUEUE_LEN;
+	}
+	mtx_unlock(&devsoftc.mtx);
+	return (0);
+}
+
+static int
 sysctl_devctl_queue(SYSCTL_HANDLER_ARGS)
 {
 	struct dev_event_info *n1;