linux-kernel - [PATCH] driver: dont update dev_name via device

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Date:	Sat, 18 Apr 2009 15:05:45 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>, Kay Sievers <kay.sievers@...y.org>,
	Greg KH <gregkh@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: [PATCH] driver: dont update dev_name via device_add path

From: Kay Sievers <kay.sievers@...y.org>

notice one system /proc/iomem some entries missed the name for pci_devices

it turns that dev->dev.kobj name is changed after device_add.

for pci code:
via acpi_pci_root_driver.ops.add (aka acpi_pci_root_add) ==> pci_acpi_scan_root
is used to scan pci bus/device, and at the same time we read the resource for pci_dev
in the pci_read_bases, we have res->name = pci_name(pci_dev); pci_name is calling dev_name.

later via acpi_pci_root_driver.ops.start (aka acpi_pci_root_start) ==> pci_bus_add_device to
add all pci_dev in kobj tree.
pci_bus_add_device will call device_add.

actually in device_add

        /* first, register with generic layer. */
        error = kobject_add(&dev->kobj, dev->kobj.parent, "%s", dev_name(dev));
        if (error)
                goto Error;

will get one new name for that kobj, old name is freed.

[Impact: fix corrupted names in /proc/iomem ]

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 drivers/base/core.c |    3 ++-
 lib/kobject.c       |    3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -891,7 +891,8 @@ int device_add(struct device *dev)
 		set_dev_node(dev, dev_to_node(parent));
 
 	/* first, register with generic layer. */
-	error = kobject_add(&dev->kobj, dev->kobj.parent, "%s", dev_name(dev));
+	/* we require the name to be set before, and pass NULL */
+	error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
 	if (error)
 		goto Error;
 
Index: linux-2.6/lib/kobject.c
===================================================================
--- linux-2.6.orig/lib/kobject.c
+++ linux-2.6/lib/kobject.c
@@ -218,6 +218,9 @@ int kobject_set_name_vargs(struct kobjec
 	const char *old_name = kobj->name;
 	char *s;
 
+	if (kobj->name && !fmt)
+		return 0;
+
 	kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
 	if (!kobj->name)
 		return -ENOMEM;
--
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