From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 25 Mar 2016 16:02:13 +0000 (-0700)
Subject: Revert "ppdev: use new parport device model"
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=1701f680407c;p=openwrt%2Fstaging%2Fblogic.git

Revert "ppdev: use new parport device model"

This reverts commit e7223f18603374d235d8bb0398532323e5f318b9.

It causes problems when a ppdev tries to register before the parport
driver has been registered with the device model. That will trigger the

        BUG_ON(!drv->bus->p);

at drivers/base/driver.c:153. The call chain is

  kernel_init ->
    kernel_init_freeable ->
      do_one_initcall ->
        ppdev_init ->
          __parport_register_driver ->
            driver_register *BOOM*

Reported-by: kernel test robot <fengguang.wu@intel.com>
Reported-by: Ross Zwisler <zwisler@gmail.com>
Reported-by: Petr Mladek <pmladek@suse.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index d23368874710..f8a483c67b07 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -286,7 +286,7 @@ static int register_device(int minor, struct pp_struct *pp)
 	struct parport *port;
 	struct pardevice *pdev = NULL;
 	char *name;
-	struct pardev_cb ppdev_cb;
+	int fl;
 
 	name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor);
 	if (name == NULL)
@@ -299,11 +299,9 @@ static int register_device(int minor, struct pp_struct *pp)
 		return -ENXIO;
 	}
 
-	memset(&ppdev_cb, 0, sizeof(ppdev_cb));
-	ppdev_cb.irq_func = pp_irq;
-	ppdev_cb.flags = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
-	ppdev_cb.private = pp;
-	pdev = parport_register_dev_model(port, name, &ppdev_cb, minor);
+	fl = (pp->flags & PP_EXCL) ? PARPORT_FLAG_EXCL : 0;
+	pdev = parport_register_device(port, name, NULL,
+				       NULL, pp_irq, fl, pp);
 	parport_put_port(port);
 
 	if (!pdev) {
@@ -801,23 +799,10 @@ static void pp_detach(struct parport *port)
 	device_destroy(ppdev_class, MKDEV(PP_MAJOR, port->number));
 }
 
-static int pp_probe(struct pardevice *par_dev)
-{
-	struct device_driver *drv = par_dev->dev.driver;
-	int len = strlen(drv->name);
-
-	if (strncmp(par_dev->name, drv->name, len))
-		return -ENODEV;
-
-	return 0;
-}
-
 static struct parport_driver pp_driver = {
 	.name		= CHRDEV,
-	.probe		= pp_probe,
-	.match_port	= pp_attach,
+	.attach		= pp_attach,
 	.detach		= pp_detach,
-	.devmodel	= true,
 };
 
 static int __init ppdev_init(void)