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Commit f4660cc9 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Greg Kroah-Hartman
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vhost/vsock: use static minor number 



Vhost-vsock is a software device so there is no probe call that causes
the driver to register its misc char device node.  This creates a
chicken and egg problem: userspace applications must open
/dev/vhost-vsock to use the driver but the file doesn't exist until the
kernel module has been loaded.

Use the devname modalias mechanism so that /dev/vhost-vsock is created
at boot.  The vhost_vsock kernel module is automatically loaded when the
first application opens /dev/host-vsock.

Note that the "reserved for local use" range in
Documentation/admin-guide/devices.txt is incorrect.  The userio driver
already occupies part of that range.  I've updated the documentation
accordingly.

Cc: device@lanana.org
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ff35eb23

Documentation/admin-guide/devices.txt

+3 −1
Original line number Diff line number Diff line
@@ -369,8 +369,10 @@ 
		237 = /dev/loop-control Loopback control device

		238 = /dev/vhost-net	Host kernel accelerator for virtio net

		239 = /dev/uhid		User-space I/O driver support for HID subsystem

		240 = /dev/userio	Serio driver testing device

		241 = /dev/vhost-vsock	Host kernel driver for virtio vsock



		240-254			Reserved for local use

		242-254			Reserved for local use

		255			Reserved for MISC_DYNAMIC_MINOR



  11 char	Raw keyboard device	(Linux/SPARC only)

drivers/vhost/vsock.c

+3 −1
Original line number Diff line number Diff line
@@ -706,7 +706,7 @@ static const struct file_operations vhost_vsock_fops = { 
};



static struct miscdevice vhost_vsock_misc = {

	.minor = MISC_DYNAMIC_MINOR,

	.minor = VHOST_VSOCK_MINOR,

	.name = "vhost-vsock",

	.fops = &vhost_vsock_fops,

};
@@ -778,3 +778,5 @@ module_exit(vhost_vsock_exit); 
MODULE_LICENSE("GPL v2");

MODULE_AUTHOR("Asias He");

MODULE_DESCRIPTION("vhost transport for vsock ");

MODULE_ALIAS_MISCDEV(VHOST_VSOCK_MINOR);

MODULE_ALIAS("devname:vhost-vsock");

include/linux/miscdevice.h

+1 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#define VHOST_NET_MINOR		238

#define UHID_MINOR		239

#define USERIO_MINOR		240

#define VHOST_VSOCK_MINOR	241

#define MISC_DYNAMIC_MINOR	255



struct device;