linux-kernel - Re: [PATCH] pci: keep pci device resource name pointer right.

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Date:	Sat, 18 Apr 2009 12:19:21 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org, Greg KH <gregkh@...e.de>
Subject: Re: [PATCH] pci: keep pci device resource name pointer right.

Linus Torvalds wrote:
> 
> On Fri, 17 Apr 2009, Yinghai Lu wrote:
>> it turns that we need to reget res->name because dev->dev.kobj name is changed
>> after device_add.
> 
> Can we not make the rule be that the name should just be set before?
> 
> IOW, there is something else broken, I think. Rather than put this ugly 
> band-aid, why now make sure that whoever had that broken name fixes it?
> 

driver core guys are enforcing to use dev_name(device) instead of referring it.

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 we read the resource for pci_dev  at this point still need to use bus->devices to go over all pci_devices if needed.
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.

Will try to make kobject_add more smart to reuse the old one.

YH
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