From 0389e9be63c5e24ecedbb366c5682ddc2ff4de60 Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Fri, 24 Sep 2021 12:10:18 -0600
Subject: [PATCH] bus: retire DF_REBID

I did DF_REBID to allow for 'hoover' drivers that would attach to
otherwise unattached devices in the tree. This notion didn't catch on as
it was tricky to make work well and it was easier to just publish a /dev
node of some flavor by the parent device. It's been nothing but dead
weight for a long time.

Reviewed by:		mav
Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D32056
---
 sys/kern/subr_bus.c | 41 ++++++-----------------------------------
 sys/sys/bus.h       |  1 -
 2 files changed, 6 insertions(+), 36 deletions(-)

diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index 5e1b561155b..3f84b6e0c56 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -2083,10 +2083,9 @@ device_probe_child(device_t dev, device_t child)
 		panic("device_probe_child: parent device has no devclass");
 
 	/*
-	 * If the state is already probed, then return.  However, don't
-	 * return if we can rebid this object.
+	 * If the state is already probed, then return.
 	 */
-	if (child->state == DS_ALIVE && (child->flags & DF_REBID) == 0)
+	if (child->state == DS_ALIVE)
 		return (0);
 
 	for (; dc; dc = dc->parent) {
@@ -2188,29 +2187,7 @@ device_probe_child(device_t dev, device_t child)
 	/*
 	 * If we found a driver, change state and initialise the devclass.
 	 */
-	/* XXX What happens if we rebid and got no best? */
 	if (best) {
-		/*
-		 * If this device was attached, and we were asked to
-		 * rescan, and it is a different driver, then we have
-		 * to detach the old driver and reattach this new one.
-		 * Note, we don't have to check for DF_REBID here
-		 * because if the state is > DS_ALIVE, we know it must
-		 * be.
-		 *
-		 * This assumes that all DF_REBID drivers can have
-		 * their probe routine called at any time and that
-		 * they are idempotent as well as completely benign in
-		 * normal operations.
-		 *
-		 * We also have to make sure that the detach
-		 * succeeded, otherwise we fail the operation (or
-		 * maybe it should just fail silently?  I'm torn).
-		 */
-		if (child->state > DS_ALIVE && best->driver != child->driver)
-			if ((result = device_detach(dev)) != 0)
-				return (result);
-
 		/* Set the winning driver, devclass, and flags. */
 		if (!child->devclass) {
 			result = device_set_devclass(child, best->driver->name);
@@ -2229,11 +2206,7 @@ device_probe_child(device_t dev, device_t child)
 			 * sure that we have the right description.
 			 */
 			DEVICE_PROBE(child);
-#if 0
-			child->flags |= DF_REBID;
-#endif
-		} else
-			child->flags &= ~DF_REBID;
+		}
 		child->state = DS_ALIVE;
 
 		bus_data_generation_update();
@@ -2921,7 +2894,7 @@ device_probe(device_t dev)
 
 	GIANT_REQUIRED;
 
-	if (dev->state >= DS_ALIVE && (dev->flags & DF_REBID) == 0)
+	if (dev->state >= DS_ALIVE)
 		return (-1);
 
 	if (!(dev->flags & DF_ENABLED)) {
@@ -4145,8 +4118,7 @@ bus_generic_driver_added(device_t dev, driver_t *driver)
 
 	DEVICE_IDENTIFY(driver, dev);
 	TAILQ_FOREACH(child, &dev->children, link) {
-		if (child->state == DS_NOTPRESENT ||
-		    (child->flags & DF_REBID))
+		if (child->state == DS_NOTPRESENT)
 			device_probe_and_attach(child);
 	}
 }
@@ -5334,7 +5306,6 @@ print_device_short(device_t dev, int indent)
 	    (dev->flags&DF_FIXEDCLASS? "fixed,":""),
 	    (dev->flags&DF_WILDCARD? "wildcard,":""),
 	    (dev->flags&DF_DESCMALLOCED? "descmalloced,":""),
-	    (dev->flags&DF_REBID? "rebiddable,":""),
 	    (dev->flags&DF_SUSPENDED? "suspended,":""),
 	    (dev->ivars? "":"no "),
 	    (dev->softc? "":"no "),
@@ -5736,7 +5707,7 @@ devctl2_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
 	/* Perform the requested operation. */
 	switch (cmd) {
 	case DEV_ATTACH:
-		if (device_is_attached(dev) && (dev->flags & DF_REBID) == 0)
+		if (device_is_attached(dev))
 			error = EBUSY;
 		else if (!device_is_enabled(dev))
 			error = ENXIO;
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index ff86cbcf457..bf51bdbef38 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -90,7 +90,6 @@ struct u_device {
 #define	DF_QUIET	0x10		/* don't print verbose attach message */
 #define	DF_DONENOMATCH	0x20		/* don't execute DEVICE_NOMATCH again */
 #define	DF_EXTERNALSOFTC 0x40		/* softc not allocated by us */
-#define	DF_REBID	0x80		/* Can rebid after attach */
 #define	DF_SUSPENDED	0x100		/* Device is suspended. */
 #define	DF_QUIET_CHILDREN 0x200		/* Default to quiet for all my children */
 #define	DF_ATTACHED_ONCE 0x400		/* Has been attached at least once */
-- 
2.45.2