linux-kernel - Re: [2/9] driver core fixes: device_register() retval check in platform.c

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Date:	Mon, 25 Sep 2006 16:58:30 +0200
From:	Cornelia Huck <cornelia.huck@...ibm.com>
To:	Russell King <rmk+lkml@....linux.org.uk>
Cc:	Greg K-H <greg@...ah.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [2/9] driver core fixes: device_register() retval check in
 platform.c

On Sat, 23 Sep 2006 22:10:32 +0100,
Russell King <rmk+lkml@....linux.org.uk> wrote:

> I don't think there's much value in patches such as this - if the
> platform bus type didn't register, what happens when we then try
> to register a platform device driver or a platform device?  ISTR
> doing that before the bus type is registered leads to an OOPS.

Yes, since the klists have not yet been initialized.

> So, presumably to do this properly, if the platform_bus_type failed
> to register, you need to force all platform device/platform device
> driver registrations to also fail.

We should fail registration (gracefully) of all devices/drivers which
specify a bus that is !NULL but has not been registered. Unfortunately,
I don't see an easy way to do this.

However, we can fail the registration of devices that specify a parent
that is !NULL but not yet added to the tree. This catches platform
devices registering before platform_bus_type (since platform_bus is not
registered then), similar for other bus types like iucv.
(Unfortunately, not drivers...)


From: Cornelia Huck <cornelia.huck@...ibm.com>

Force parent devices to be registered before their children. Otherwise we'll
oops when creating the child's sysfs directory.

Signed-off-by: Cornelia Huck <cornelia.huck@...ibm.com>

---
 drivers/base/bus.c  |    6 ++++--
 drivers/base/core.c |    5 ++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

--- linux-2.6.18-mm1.orig/drivers/base/core.c
+++ linux-2.6.18-mm1/drivers/base/core.c
@@ -474,7 +474,10 @@ int device_add(struct device *dev)
 	}
 
 	parent = get_device(dev->parent);
-
+	if (parent && !device_is_registered(parent)) {
+		error = -EINVAL;
+		goto Error;
+	}
 	pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
 
 	/* first, register with generic layer. */
--- linux-2.6.18-mm1.orig/drivers/base/bus.c
+++ linux-2.6.18-mm1/drivers/base/bus.c
@@ -418,7 +418,8 @@ int bus_attach_device(struct device * de
 			ret = 0;
 		} else
 			dev->is_registered = 0;
-	}
+	} else
+		dev->is_registered = 1;
 	return ret;
 }
 
@@ -443,7 +444,8 @@ void bus_remove_device(struct device * d
 		pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
 		device_release_driver(dev);
 		put_bus(dev->bus);
-	}
+	} else
+		dev->is_registered = 0;
 }
 
 static int driver_add_attrs(struct bus_type * bus, struct device_driver * drv)
-
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