linux-kernel - Re: [PATCH] pci: Add support for unbinding the generic PCI host controller

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Message-ID: <ca98db38-cfe3-eafd-cf04-2f927b1d2dea@siemens.com>
Date:   Mon, 22 Aug 2016 13:23:57 -0400
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Will Deacon <will.deacon@....com>, linux-pci@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pci: Add support for unbinding the generic PCI host
 controller

On 2016-08-22 13:05, Bjorn Helgaas wrote:
> Hi Jan,
> 
> On Tue, Jun 21, 2016 at 08:07:50PM +0200, Jan Kiszka wrote:
>> Particularly useful when working in virtual environments where the
>> controller may come and go, but possibly not only there.
> 
> I'm not sure where we're at with this.  Will had a few questions about
> the tear-down paths, and I couldn't tell what the resolution was.

Likely already the existing code leaks memory when rolling back on
errors. That needs to be analysed and resolved. Then it will be simple
to make unbinding leak-free as well.

I'm not familiar enough with the functions involved and still need to
find the required time to dig into this.

Jan

> 
>> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
>> ---
>>  drivers/pci/ecam.h                  |  1 +
>>  drivers/pci/host/pci-host-common.c  | 13 +++++++++++++
>>  drivers/pci/host/pci-host-generic.c |  1 +
>>  3 files changed, 15 insertions(+)
>>
>> diff --git a/drivers/pci/ecam.h b/drivers/pci/ecam.h
>> index 9878beb..5a5f607 100644
>> --- a/drivers/pci/ecam.h
>> +++ b/drivers/pci/ecam.h
>> @@ -63,5 +63,6 @@ extern struct pci_ecam_ops pci_generic_ecam_ops;
>>  /* for DT-based PCI controllers that support ECAM */
>>  int pci_host_common_probe(struct platform_device *pdev,
>>  			  struct pci_ecam_ops *ops);
>> +int pci_host_common_remove(struct platform_device *pdev);
>>  #endif
>>  #endif
>> diff --git a/drivers/pci/host/pci-host-common.c b/drivers/pci/host/pci-host-common.c
>> index 8cba7ab..c0ff4b1 100644
>> --- a/drivers/pci/host/pci-host-common.c
>> +++ b/drivers/pci/host/pci-host-common.c
>> @@ -164,6 +164,19 @@ int pci_host_common_probe(struct platform_device *pdev,
>>  	}
>>  
>>  	pci_bus_add_devices(bus);
>> +	platform_set_drvdata(pdev, bus);
>> +	return 0;
>> +}
>> +
>> +int pci_host_common_remove(struct platform_device *pdev)
>> +{
>> +	struct pci_bus *bus = platform_get_drvdata(pdev);
>> +
>> +	pci_lock_rescan_remove();
>> +	pci_stop_root_bus(bus);
>> +	pci_remove_root_bus(bus);
>> +	pci_unlock_rescan_remove();
>> +
>>  	return 0;
>>  }
>>  
>> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
>> index 6eaceab..0a2e75b 100644
>> --- a/drivers/pci/host/pci-host-generic.c
>> +++ b/drivers/pci/host/pci-host-generic.c
>> @@ -65,6 +65,7 @@ static struct platform_driver gen_pci_driver = {
>>  		.of_match_table = gen_pci_of_match,
>>  	},
>>  	.probe = gen_pci_probe,
>> +	.remove = pci_host_common_remove,
>>  };
>>  module_platform_driver(gen_pci_driver);
>>  
>> -- 
>> 2.1.4

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