From: Cyrille Pitchen <cyrille.pitchen@free-electrons.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Kishon Vijay Abraham I <kishon@ti.com>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
adouglas@cadence.com, stelford@cadence.com, dgary@cadence.com,
kgopi@cadence.com, eandrews@cadence.com,
thomas.petazzoni@free-electrons.com, sureshp@cadence.com,
nsekhar@ti.com, linux-kernel@vger.kernel.org, robh@kernel.org,
devicetree@vger.kernel.org
Subject: Re: [PATCH 0/5] PCI: Add support to the Cadence PCIe controller
Date: Thu, 30 Nov 2017 19:45:16 +0100 [thread overview]
Message-ID: <a02af401-2eb8-dc34-6f3c-092f04ec2636@free-electrons.com> (raw)
In-Reply-To: <20171130181819.GD12096@red-moon>
Hi all,
Le 30/11/2017 à 19:18, Lorenzo Pieralisi a écrit :
> On Thu, Nov 30, 2017 at 12:43:20PM +0530, Kishon Vijay Abraham I wrote:
>
> [...]
>
>>>> For linux-next, I applied this series on top of Kishon's patch
>>>> ("PCI: endpoint: Use EPC's device in dma_alloc_coherent/dma_free_coherent")
>>>> otherwise dma_alloc_coherent() fails when called by pci_epf_alloc_space().
>>>>
>>>> Also, I patched drivers/Makefile rather than drivers/pci/Makefile to make
>>>> the drivers/pci/cadence/pcie-cadence-ep.o linked after
>>
>> The reason to patch drivers/Makefile should be because pcie-cadence-ep has to
>> be compiled even when CONFIG_PCI is not enabled. CONFIG_PCI enables host
>> specific features and ENDPOINT shouldn't depend on CONFIG_PCI.
>>>> drivers/pci/endpoint/*.o objects, otherwise the built-in pci-cadence-ep
>>>> driver would be probed before the PCI endpoint framework would have been
>>>> initialized, which results in a kernel crash.
>>>
>>> Nice :( - isn't there a way to improve this (ie probe deferral or
>>> registering the EPF bus earlier) ?
>>>
>>>> I guess this is the reason why the "pci/dwc" line was also put in
>>>> drivers/Makefile, right after the "pci/endpoint" line.
>>>
>>> Or probably the other way around - see commit 5e8cb4033807
>>>
>>> @Kishon, thoughts ?
>>
>> Lorenzo, ordering Makefile is one way to initialize EP core before
>
> Makefile ordering is fragile, I do not like relying on it.
>
>> other drivers. the other way is to have PCI EP core have a different
>> initcall level.. subsys_initcall??
>
> Yes, registering the bus at eg postcore_initcall() as PCI does should do
> (if that's the problem this is solving) but still, the code must not
> crash if the ordering is not correct, we have to fix this regardless.
>
> I would appreciate if Cyrille can debug the cause of the kernel crash
> so that we can fix it in the longer term.
>
I had the crash kernel few weeks ago hence I have to test again to confirm
but if I remember correctly it was a NULL pointer dereferencing crash:
cdns_pcie_ep_probe()
|
+--> devm_pci_epc_create()
|
+--> __devm_pci_ep_create()
|
+--> __pci_epc_create()
|
+--> pci_ep_cfs_add_epc_group()
|
| /*
| * Here controllers_group is still NULL because
| * pci_ep_cfs_init() has not been called yet.
| */
+--> configfs_register_group(controllers_group, ...)
|
+--> link_group()
/* Dereferencing NULL pointer */
Best regards,
Cyrille
> Thanks,
> Lorenzo
>
--
Cyrille Pitchen, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2017-11-30 18:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-23 15:01 [PATCH 0/5] PCI: Add support to the Cadence PCIe controller Cyrille Pitchen
2017-11-23 15:01 ` [PATCH 2/5] dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe host controller Cyrille Pitchen
[not found] ` <895cbb8f862c712b78f780a53e05d5429d24cc35.1511439189.git.cyrille.pitchen-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-11-26 19:32 ` Rob Herring
[not found] ` <cover.1511439189.git.cyrille.pitchen-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-11-23 15:01 ` [PATCH 1/5] PCI: Add vendor ID for Cadence Cyrille Pitchen
[not found] ` <a93032cbbe02dc9efef8536a4b2a851d1b08ab6f.1511439189.git.cyrille.pitchen-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-12-06 21:27 ` Bjorn Helgaas
2017-11-23 15:01 ` [PATCH 3/5] PCI: cadence: Add host driver for Cadence PCIe controller Cyrille Pitchen
2017-11-28 20:41 ` Bjorn Helgaas
2017-11-28 20:46 ` Bjorn Helgaas
2017-11-29 14:14 ` Lorenzo Pieralisi
[not found] ` <20171128204114.GE11228-1RhO1Y9PlrlHTL0Zs8A6p5iNqAH0jzoTYJqu5kTmcBRl57MIdRCFDg@public.gmane.org>
2017-11-29 8:19 ` Thomas Petazzoni
2017-11-29 15:55 ` Bjorn Helgaas
2017-12-01 10:37 ` Cyrille Pitchen
[not found] ` <c6a0d70d-d584-2db8-f862-0c3ddbf6939d-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-12-01 16:20 ` Lorenzo Pieralisi
2017-11-29 17:34 ` Lorenzo Pieralisi
2017-12-03 20:44 ` Cyrille Pitchen
2017-12-04 18:20 ` Lorenzo Pieralisi
2017-12-04 18:49 ` Ard Biesheuvel
[not found] ` <CAKv+Gu_1XZmsKJ_7ay7D74xSAhDW0y++7-CC3YfG7LOUcNZSqA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-12-06 11:32 ` Lorenzo Pieralisi
2017-12-13 16:42 ` Cyrille Pitchen
2017-11-29 18:25 ` Lorenzo Pieralisi
2017-11-30 10:06 ` Lorenzo Pieralisi
2017-11-23 15:01 ` [PATCH 4/5] dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe endpoint controller Cyrille Pitchen
2017-11-26 19:33 ` Rob Herring
2017-11-23 15:01 ` [PATCH 5/5] PCI: cadence: add EndPoint Controller driver for Cadence PCIe controller Cyrille Pitchen
2017-12-01 12:20 ` Lorenzo Pieralisi
2017-12-04 14:56 ` Cyrille Pitchen
2017-12-05 9:19 ` Kishon Vijay Abraham I
2017-12-07 10:05 ` Philippe Ombredanne
[not found] ` <CAOFm3uGQzAOrAmQLx7uJ0SJGQxMSB+oAniq9wd93tvupKWv=uA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-12-13 16:03 ` Cyrille Pitchen
[not found] ` <ed6d811e-608e-e6aa-7b07-2f2d2d68adbd-l0cyMroinI0@public.gmane.org>
2017-12-13 16:50 ` Cyrille Pitchen
2017-12-14 17:03 ` Cyrille Pitchen
[not found] ` <e43929c8-e283-f774-eca3-3b0ffcdfb49d-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-12-15 5:49 ` Kishon Vijay Abraham I
[not found] ` <4c1e8ba7-8084-7802-df4e-47c6f3ed7816-l0cyMroinI0@public.gmane.org>
2017-12-15 11:49 ` Cyrille Pitchen
2017-11-28 15:50 ` [PATCH 0/5] PCI: Add support to the " Lorenzo Pieralisi
2017-11-30 7:13 ` Kishon Vijay Abraham I
2017-11-30 18:18 ` Lorenzo Pieralisi
2017-11-30 18:45 ` Cyrille Pitchen [this message]
[not found] ` <a02af401-2eb8-dc34-6f3c-092f04ec2636-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
2017-11-30 20:05 ` Cyrille Pitchen
2017-11-30 23:05 ` Bjorn Helgaas
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