From 1da480e9b7de87ebb5a9c01585eec43a75930415 Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <riastradh@NetBSD.org>
Date: Mon, 31 Jan 2022 14:26:43 +0000
Subject: [PATCH 36/39] driver(9): Make vdevgone call config_detach_commit if
 appropriate.

Make sure to do this before spec_node_lookup_by_dev -- that might wait
for a concurrent revoke to complete, which in turn might wait for a
concurrent open to complete, which in turn might be waiting for the
device to commit to detaching.
---
 sys/kern/subr_devsw.c | 36 ++++++++++++++++++++++++++++++++++++
 sys/kern/vfs_subr.c   | 14 ++++++++++++++
 sys/sys/conf.h        |  4 ++++
 3 files changed, 54 insertions(+)

diff --git a/sys/kern/subr_devsw.c b/sys/kern/subr_devsw.c
index d24480114f94..3087606aebf2 100644
--- a/sys/kern/subr_devsw.c
+++ b/sys/kern/subr_devsw.c
@@ -1068,6 +1068,24 @@ bdev_discard(dev_t dev, off_t pos, off_t len)
 	return rv;
 }
 
+void
+bdev_detached(dev_t dev)
+{
+	const struct bdevsw *d;
+	device_t dv;
+	int unit;
+
+	if ((d = bdevsw_lookup(dev)) == NULL)
+		return;
+	if (d->d_devtounit == NULL)
+		return;
+	if ((unit = (*d->d_devtounit)(dev)) == -1)
+		return;
+	if ((dv = device_lookup(d->d_cfdriver, unit)) == NULL)
+		return;
+	config_detach_commit(dv);
+}
+
 int
 cdev_open(dev_t dev, int flag, int devtype, lwp_t *l)
 {
@@ -1288,6 +1306,24 @@ cdev_type(dev_t dev)
 	return d->d_flag & D_TYPEMASK;
 }
 
+void
+cdev_detached(dev_t dev)
+{
+	const struct cdevsw *d;
+	device_t dv;
+	int unit;
+
+	if ((d = cdevsw_lookup(dev)) == NULL)
+		return;
+	if (d->d_devtounit == NULL)
+		return;
+	if ((unit = (*d->d_devtounit)(dev)) == -1)
+		return;
+	if ((dv = device_lookup(d->d_cfdriver, unit)) == NULL)
+		return;
+	config_detach_commit(dv);
+}
+
 /*
  * nommap(dev, off, prot)
  *
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index a64cffb97054..f6504733960d 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -511,6 +511,20 @@ vdevgone(int maj, int minl, int minh, enum vtype type)
 
 	for (mn = minl; mn <= minh; mn++) {
 		dev = makedev(maj, mn);
+		/*
+		 * Notify anyone trying to get at this device that it
+		 * has been detached, and then revoke it.
+		 */
+		switch (type) {
+		case VBLK:
+			bdev_detached(dev);
+			break;
+		case VCHR:
+			cdev_detached(dev);
+			break;
+		default:
+			panic("invalid specnode type: %d", type);
+		}
 		/*
 		 * Passing 0 as flags, instead of VDEAD_NOWAIT, means
 		 * spec_node_lookup_by_dev will wait for vnodes it
diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 16dd87e5480c..210a237b8c43 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -172,6 +172,8 @@ dev_type_dump(bdev_dump);
 dev_type_size(bdev_size);
 dev_type_discard(bdev_discard);
 
+void	bdev_detached(dev_t);
+
 dev_type_open(cdev_open);
 dev_type_close(cdev_close);
 dev_type_read(cdev_read);
@@ -184,6 +186,8 @@ dev_type_mmap(cdev_mmap);
 dev_type_kqfilter(cdev_kqfilter);
 dev_type_discard(cdev_discard);
 
+void	cdev_detached(dev_t);
+
 int	cdev_type(dev_t);
 int	cdev_flags(dev_t);
 int	bdev_type(dev_t);