Date:	Thu, 05 Jun 2008 11:32:54 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Alex Chiang <achiang@...com>, jbarnes@...tuousgeek.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	kaneshige.kenji@...fujitsu.com, Matthew Wilcox <matthew@....cx>,
	Andrew Morton <akpm@...ux-foundation.org>,
	kristen.c.accardi@...el.com, greg@...ah.com, lenb@...nel.org,
	pbadari@...ibm.com, linux-pci@...r.kernel.org,
	pcihpd-discuss@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4, v14] PCI, ACPI: Physical PCI slot objects

Hi Alex-san,

I tried to test your patch using latest linux-next, but I could
not apply your patch with the following messages:

$ quilt push
Applying patch patches/fakephp-construct-one-fakephp-slot-per-pci-slot.patch
(Stripping trailing CRs from patch.)
patching file drivers/pci/hotplug/fakephp.c
Hunk #2 succeeded at 102 (offset 1 line).
Hunk #3 FAILED at 116.
Hunk #4 succeeded at 154 (offset 4 lines).
Hunk #5 succeeded at 299 (offset 1 line).
Hunk #6 succeeded at 314 (offset 4 lines).
patch unexpectedly ends in middle of line
1 out of 6 hunks FAILED -- rejects in file drivers/pci/hotplug/fakephp.c
patch unexpectedly ends in middle of line
Patch patches/fakephp-construct-one-fakephp-slot-per-pci-slot.patch does not apply (enforce with -f)


I think maybe your patch is conflicting with the following patch.

commit 372fa8fa0a77c47c7bcfae0ccd14e0c5f97d17fe
Author: Kay Sievers <kay.sievers@...y.org>
Date:   Fri May 2 06:02:41 2008 +0200

    driver-core: prepare for removal of 20 char limit from struct device

    The access of struct device->bus_id is replaced by dev_name(), to
    be able to use the non-limited kobject name after the conversion
    of the device register callers.

Thanks,
Kenji Kaneshige


Alex Chiang wrote:
> Hi Jesse, Ben, Kenji-san,
> 
> This is v14 of the physical PCI slot series.
> 
> This patchset has been kicking around -mm for the past few
> months, and they were getting clobbered on a continual basis, so
> let's say I'm quite motivated to get them into mainline. ;)
> 
> This mail describes two things:
> 
> 	- an update for handling pSeries
> 	- explanation of how I did not regress Kenji-san's latest
> 	  changes
> 
> Review comments are much appreciated.
> 
> -----------------------
> pSeries-related changes
> -----------------------
> The most recent outstanding issue with this series was breakage
> with pSeries. In a nutshell, the problem was:
> 
> 	- pci_hp_register() interface changed to require a devfn
> 	  when registering a slot
> 
> 	- pSeries doesn't necessarily know the devfn of an
> 	  unpopulated slot
> 
> There are more details, of course, and they are in the archives.
> I can dig them up if people want more context.
> 
> After working offline with BenH and Willy, we thought that the
> best way forward was for the new infrastructure to provide a new
> API, pci_update_slot_number(), which can be used by callers to
> modify the slot number after slot creation. 
> 
> This change goes hand in hand with modifying the semantics of
> pci_hp_register() where callers are now allowed to pass -1 for
> slot_nr to create a 'placeholder' slot.
> 
> The third related change is that the infrastructure will only
> display an 'address' value of 'dddd:bb' (domain:bus) when the
> device is -1. In the normal case, the full address of dddd:bb:dd
> is displayed.
> 
> I did fold an earlier -mm fixup patch into these changes to
> improve future bisectability.
> 
> I added kerneldoc to explain the APIs.
> 
> -----------------------------
> maintaining Kenji-san's fixes
> -----------------------------
> Finally, this patch series slightly changes the logic introduced
> by Kenji-san's patches:
> 
> 	9e4f2e8d4ddb04ad16a3828cd9a369a5a5287009
> 	a86161b3134465f072d965ca7508ec9c1e2e52c7
> 
> For a86161b31344, the check against registering a slot with the
> same name multiple times is removed. That check prevents a
> scenario where multiple pcihp drivers try to claim the same slot.
> 
> The check is removed because the new code allows multiple callers
> of pci_create_slot(). One callsite is pci_hp_register(), the
> other is in the ACPI slot detection driver provided in patch 4/4.
> In the case of multiple legitimate callers, the correct thing to
> do is refcount the struct pci_slot's kobj.
> 
> In the case of two pcihp drivers attempting to claim the same
> slot, pci_hp_register() returns -EBUSY to indicate it has already
> been claimed. This logic has been part of the patch series from
> the beginning.
> 
> Thus, the end behavior introduced by a86161b31344 is preserved,
> although in a slightly different implementation.
> 
> The firmware defect that Kenji-san is trying to fix with
> 9e4f2e8d4d is the case where broken firmware will present the
> kernel with slots like bb1:dd1, name "A" and bb2:dd2, name "A".
> 
> In other words, two different busses or two different devices on
> the same bus, but both have the same name.
> 
> In this case, pci_create_slot() thinks they are two different
> physical slots (which is true), and tries to register them with
> the kobject core, which will then complain about registering two
> objects with the same name. -EEXIST will be returned back up
> through the pcihp core and back to pciehp, which will then printk
> the message added by 9e4f2e8d4d.
> 
> Thus, the condition Kenji-san is trying to warn about with
> 9e4f2e8d4d is preserved.
> 
> Thanks,
> 
> /ac
> 
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> 
> 


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