From: Alex Hornung <ahornung@gmail.com>
Date: Fri, 11 Sep 2009 06:10:09 +0000 (+0100)
Subject: devfs - Add new make_dev_covering
X-Git-Tag: v2.4.0~30^2~3
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/47ae500fd01ad33b1d1c66e8c07e38876dab6f02

devfs - Add new make_dev_covering

* Add a new make_dev_covering which is used by systems such as the disk
  subsystem, that make_dev for an underlying device.
---

diff --git a/sys/kern/kern_conf.c b/sys/kern/kern_conf.c
index c9f458535a..d933a97ec3 100644
--- a/sys/kern/kern_conf.c
+++ b/sys/kern/kern_conf.c
@@ -186,7 +186,7 @@ make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 	 */
 	compile_dev_ops(ops);
 
-	devfs_dev = devfs_new_cdev(ops, minor);
+	devfs_dev = devfs_new_cdev(ops, minor, NULL);
 	__va_start(ap, fmt);
 	kvsnrprintf(devfs_dev->si_name, sizeof(devfs_dev->si_name),
 		    32, fmt, ap);
@@ -200,6 +200,38 @@ make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 	return (devfs_dev);
 }
 
+/*
+ * make_dev_covering has equivalent functionality to make_dev, except that it
+ * also takes the cdev of the underlying device. Hence this function should
+ * only be used by systems and drivers which create devices covering others
+ */
+cdev_t
+make_dev_covering(struct dev_ops *ops, cdev_t rdev, int minor, uid_t uid,
+	    gid_t gid, int perms, const char *fmt, ...)
+{
+	cdev_t	devfs_dev;
+	__va_list ap;
+
+	/*
+	 * compile the cdevsw and install the device
+	 */
+	compile_dev_ops(ops);
+
+	devfs_dev = devfs_new_cdev(ops, minor, rdev);
+	__va_start(ap, fmt);
+	kvsnrprintf(devfs_dev->si_name, sizeof(devfs_dev->si_name),
+		    32, fmt, ap);
+	__va_end(ap);
+
+	devfs_debug(DEVFS_DEBUG_INFO,
+		    "make_dev called for %s\n",
+		    devfs_dev->si_name);
+	devfs_create_dev(devfs_dev, uid, gid, perms);
+
+	return (devfs_dev);
+}
+
+
 
 cdev_t
 make_only_devfs_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
@@ -212,7 +244,7 @@ make_only_devfs_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 	 * compile the cdevsw and install the device
 	 */
 	compile_dev_ops(ops);
-	devfs_dev = devfs_new_cdev(ops, minor);
+	devfs_dev = devfs_new_cdev(ops, minor, NULL);
 
 	/*
 	 * Set additional fields (XXX DEVFS interface goes here)
@@ -239,7 +271,7 @@ make_only_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 	 * compile the cdevsw and install the device
 	 */
 	compile_dev_ops(ops);
-	devfs_dev = devfs_new_cdev(ops, minor);
+	devfs_dev = devfs_new_cdev(ops, minor, NULL);
 	devfs_dev->si_perms = perms;
 	devfs_dev->si_uid = uid;
 	devfs_dev->si_gid = gid;
diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 9522deabbb..6d4e052c2c 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -71,6 +71,7 @@ struct cdev {
 	uid_t		si_uid;
 	gid_t		si_gid;
 	int		si_perms;
+	cdev_t	si_rdev;
 	TAILQ_ENTRY(cdev) link;
 	int		si_uminor;
 	int		si_umajor;
diff --git a/sys/sys/devfs.h b/sys/sys/devfs.h
index ebd5967be7..cd2815937d 100644
--- a/sys/sys/devfs.h
+++ b/sys/sys/devfs.h
@@ -390,7 +390,7 @@ int devfs_destroy_subnames(char *);
 int devfs_destroy_dev_by_ops(struct dev_ops *, int);
 struct devfs_node *devfs_find_device_node_by_name(struct devfs_node *, char *);
 
-cdev_t devfs_new_cdev(struct dev_ops *, int);
+cdev_t devfs_new_cdev(struct dev_ops *, int, cdev_t);
 
 cdev_t devfs_find_device_by_name(const char *, ...);
 cdev_t devfs_find_device_by_udev(udev_t);
diff --git a/sys/sys/device.h b/sys/sys/device.h
index 169bc446a6..ef46a0b3a0 100644
--- a/sys/sys/device.h
+++ b/sys/sys/device.h
@@ -364,6 +364,8 @@ void dev_ops_restore(cdev_t, struct dev_ops *);
 
 cdev_t make_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 		int perms, const char *fmt, ...) __printflike(6, 7);
+cdev_t make_dev_covering(struct dev_ops *ops, cdev_t rdev, int minor, uid_t uid,
+	    gid_t gid, int perms, const char *fmt, ...) __printflike(7, 8);
 cdev_t make_only_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
 		int perms, const char *fmt, ...) __printflike(6, 7);
 cdev_t make_only_devfs_dev(struct dev_ops *ops, int minor, uid_t uid, gid_t gid,
diff --git a/sys/vfs/devfs/devfs_core.c b/sys/vfs/devfs/devfs_core.c
index 4a38783b59..7230e644e5 100644
--- a/sys/vfs/devfs/devfs_core.c
+++ b/sys/vfs/devfs/devfs_core.c
@@ -2067,7 +2067,7 @@ devfs_fetch_ino(void)
  * fields.
  */
 cdev_t
-devfs_new_cdev(struct dev_ops *ops, int minor)
+devfs_new_cdev(struct dev_ops *ops, int minor, cdev_t rdev)
 {
 	cdev_t dev = sysref_alloc(&cdev_sysref_class);
 
@@ -2087,7 +2087,11 @@ devfs_new_cdev(struct dev_ops *ops, int minor)
 	dev->si_flags = 0;
 	dev->si_umajor = 0;
 	dev->si_uminor = minor;
-	dev->si_inode = makeudev(devfs_reference_ops(ops), minor);
+	dev->si_rdev = rdev;
+	/* If there is a backing device, we reference its ops */
+	dev->si_inode = makeudev(
+		    devfs_reference_ops((rdev)?(rdev->si_ops):(ops)),
+		    minor );
 
 	return dev;
 }
@@ -2110,7 +2114,8 @@ devfs_cdev_terminate(cdev_t dev)
 	if (locked)
 		lockmgr(&devfs_lock, LK_RELEASE);
 
-	devfs_release_ops(dev->si_ops);
+	/* If there is a backing device, we release the backing device's ops */
+	devfs_release_ops((dev->si_rdev)?(dev->si_rdev->si_ops):(dev->si_ops));
 
 	/* Finally destroy the device */
 	sysref_put(&dev->si_sysref);