Re: [PATCH 5/5] PCI: Rip out pci_bus_add_devices() from pci_scan_root_bus()

Yijing Wang
2014-11-20T01:14:39Z

On 2014/11/19 19:49, Lorenzo Pieralisi wrote:
> On Wed, Nov 19, 2014 at 07:32:49AM +0000, Yijing Wang wrote:
>> Just like pci_scan_bus(), we also should rip out
>> pci_bus_add_devices() from pci_scan_root_bus().
>> Lots platforms first call pci_scan_root_bus(), but
>> after that, they call pci_bus_size_bridges() and
>> pci_bus_assign_resources(). Place pci_bus_add_devices()
>> in pci_scan_root_bus() hurts PCI scan logic.
>> Should no functional change.
>
> I agree with the patch, I do not agree it provides no functional change.
> You are actually fixing an issue on systems where the root bus
> is scanned at device_initcall time and pci drivers may have already been
> registered, so they end up being probed with possibly unassigned
> resources as you correctly mention in the log.
>
> You could move the sequence:
>
> if (!pci_has_flag(PCI_PROBE_ONLY)) {
> pci_bus_size_bridges();
> pci_bus_assign_resources();
> }
>
> in pci_scan_root_bus() instead of taking pci_bus_add_devices() out ?

No, many drivers need additional setup before resources setup.

>
> Would this break any code ? Or add a helper function:
>
> pci_scan_root_bus(..., bool assign) ?

I don't think it's worth, this make scan function involved something not
scan business.

>
> arm64 xgene code has already been fixed by reshuffling the scanning code
> sequence.
>
> I think we should have a look at eg drivers/pci/host/pcie-xilinx.c, I
> think there is a possible initcall ordering issue there (drivers being probed
> with unassigned resources).

If pci device drivers(like network driver) are loaded before pcie host driver,
use pci_scan_root_bus() may cause problem, because pci_bus_add_devices() will
try to attach the device driver, but this time pci devices resources may not
be configured properly.

>
> Lorenzo
>
>>
>> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
>> CC: linux-alpha@vger.kernel.org
>> CC: linux-ia64@vger.kernel.org
>> CC: linux-mips@linux-mips.org
>> CC: linux-xtensa@linux-xtensa.org
>> CC: linux-arm-kernel@lists.infradead.org
>> CC: linux-sh@vger.kernel.org
>> CC: sparclinux@vger.kernel.org
>> ---
>> arch/alpha/kernel/pci.c | 2 ++
>> arch/frv/mb93090-mb00/pci-vdk.c | 6 ++++--
>> arch/ia64/sn/kernel/io_init.c | 1 +
>> arch/microblaze/pci/pci-common.c | 1 +
>> arch/mips/pci/pci.c | 1 +
>> arch/mn10300/unit-asb2305/pci.c | 5 ++++-
>> arch/s390/pci/pci.c | 2 +-
>> arch/sh/drivers/pci/pci.c | 1 +
>> arch/sparc/kernel/leon_pci.c | 1 +
>> arch/tile/kernel/pci.c | 2 ++
>> arch/tile/kernel/pci_gx.c | 2 ++
>> arch/x86/pci/common.c | 1 +
>> arch/xtensa/kernel/pci.c | 2 ++
>> drivers/pci/host/pci-xgene.c | 1 +
>> drivers/pci/probe.c | 1 -
>> 15 files changed, 24 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/alpha/kernel/pci.c b/arch/alpha/kernel/pci.c
>> index 076c35c..97f9730 100644
>> --- a/arch/alpha/kernel/pci.c
>> +++ b/arch/alpha/kernel/pci.c
>> @@ -334,6 +334,8 @@ common_init_pci(void)
>>
>> bus = pci_scan_root_bus(NULL, next_busno, alpha_mv.pci_ops,
>> hose, &resources);
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> hose->bus = bus;
>> hose->need_domain_info = need_domain_info;
>> next_busno = bus->busn_res.end + 1;
>> diff --git a/arch/frv/mb93090-mb00/pci-vdk.c b/arch/frv/mb93090-mb00/pci-vdk.c
>> index efa5d65..2b36044 100644
>> --- a/arch/frv/mb93090-mb00/pci-vdk.c
>> +++ b/arch/frv/mb93090-mb00/pci-vdk.c
>> @@ -316,6 +316,7 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>>
>> int __init pcibios_init(void)
>> {
>> + struct pci_bus *bus;
>> struct pci_ops *dir = NULL;
>> LIST_HEAD(resources);
>>
>> @@ -383,12 +384,13 @@ int __init pcibios_init(void)
>> printk("PCI: Probing PCI hardware\n");
>> pci_add_resource(&resources, &pci_ioport_resource);
>> pci_add_resource(&resources, &pci_iomem_resource);
>> - pci_scan_root_bus(NULL, 0, pci_root_ops, NULL, &resources);
>> + bus = pci_scan_root_bus(NULL, 0, pci_root_ops, NULL, &resources);
>>
>> pcibios_irq_init();
>> pcibios_fixup_irqs();
>> pcibios_resource_survey();
>> -
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> return 0;
>> }
>>
>> diff --git a/arch/ia64/sn/kernel/io_init.c b/arch/ia64/sn/kernel/io_init.c
>> index 0b5ce82..63b43a6 100644
>> --- a/arch/ia64/sn/kernel/io_init.c
>> +++ b/arch/ia64/sn/kernel/io_init.c
>> @@ -272,6 +272,7 @@ sn_pci_controller_fixup(int segment, int busnum, struct pci_bus *bus)
>> kfree(res);
>> kfree(controller);
>> }
>> + pci_bus_add_devices(bus);
>> }
>>
>> /*
>> diff --git a/arch/microblaze/pci/pci-common.c b/arch/microblaze/pci/pci-common.c
>> index 9037914..651e25d 100644
>> --- a/arch/microblaze/pci/pci-common.c
>> +++ b/arch/microblaze/pci/pci-common.c
>> @@ -1346,6 +1346,7 @@ static void pcibios_scan_phb(struct pci_controller *hose)
>> hose->bus = bus;
>>
>> hose->last_busno = bus->busn_res.end;
>> + pci_bus_add_devices(bus);
>> }
>>
>> static int __init pcibios_init(void)
>> diff --git a/arch/mips/pci/pci.c b/arch/mips/pci/pci.c
>> index 1bf60b1..f083688 100644
>> --- a/arch/mips/pci/pci.c
>> +++ b/arch/mips/pci/pci.c
>> @@ -113,6 +113,7 @@ static void pcibios_scanbus(struct pci_controller *hose)
>> if (!pci_has_flag(PCI_PROBE_ONLY)) {
>> pci_bus_size_bridges(bus);
>> pci_bus_assign_resources(bus);
>> + pci_bus_add_devices(bus);
>> }
>> }
>> }
>> diff --git a/arch/mn10300/unit-asb2305/pci.c b/arch/mn10300/unit-asb2305/pci.c
>> index 6b4339f..860aa35 100644
>> --- a/arch/mn10300/unit-asb2305/pci.c
>> +++ b/arch/mn10300/unit-asb2305/pci.c
>> @@ -345,6 +345,7 @@ void pcibios_fixup_bus(struct pci_bus *bus)
>> */
>> static int __init pcibios_init(void)
>> {
>> + struct pci_bus *bus;
>> resource_size_t io_offset, mem_offset;
>> LIST_HEAD(resources);
>>
>> @@ -376,11 +377,13 @@ static int __init pcibios_init(void)
>>
>> pci_add_resource_offset(&resources, &pci_ioport_resource, io_offset);
>> pci_add_resource_offset(&resources, &pci_iomem_resource, mem_offset);
>> - pci_scan_root_bus(NULL, 0, &pci_direct_ampci, NULL, &resources);
>> + bus = pci_scan_root_bus(NULL, 0, &pci_direct_ampci, NULL, &resources);
>>
>> pcibios_irq_init();
>> pcibios_fixup_irqs();
>> pcibios_resource_survey();
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> return 0;
>> }
>>
>> diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
>> index 552b990..98247f8 100644
>> --- a/arch/s390/pci/pci.c
>> +++ b/arch/s390/pci/pci.c
>> @@ -755,7 +755,7 @@ static int zpci_scan_bus(struct zpci_dev *zdev)
>> zpci_cleanup_bus_resources(zdev);
>> return -EIO;
>> }
>> -
>> + pci_bus_add_devices(zdev->bus);
>> zdev->bus->max_bus_speed = zdev->max_bus_speed;
>> return 0;
>> }
>> diff --git a/arch/sh/drivers/pci/pci.c b/arch/sh/drivers/pci/pci.c
>> index 1bc09ee..efc1051 100644
>> --- a/arch/sh/drivers/pci/pci.c
>> +++ b/arch/sh/drivers/pci/pci.c
>> @@ -69,6 +69,7 @@ static void pcibios_scanbus(struct pci_channel *hose)
>>
>> pci_bus_size_bridges(bus);
>> pci_bus_assign_resources(bus);
>> + pci_bus_add_devices(bus);
>> } else {
>> pci_free_resource_list(&resources);
>> }
>> diff --git a/arch/sparc/kernel/leon_pci.c b/arch/sparc/kernel/leon_pci.c
>> index 899b720..2971076 100644
>> --- a/arch/sparc/kernel/leon_pci.c
>> +++ b/arch/sparc/kernel/leon_pci.c
>> @@ -40,6 +40,7 @@ void leon_pci_init(struct platform_device *ofdev, struct leon_pci_info *info)
>>
>> /* Assign devices with resources */
>> pci_assign_unassigned_resources();
>> + pci_bus_add_devices(root_bus);
>> } else {
>> pci_free_resource_list(&resources);
>> }
>> diff --git a/arch/tile/kernel/pci.c b/arch/tile/kernel/pci.c
>> index 1f80a88..007466e 100644
>> --- a/arch/tile/kernel/pci.c
>> +++ b/arch/tile/kernel/pci.c
>> @@ -308,6 +308,8 @@ int __init pcibios_init(void)
>> pci_add_resource(&resources, &iomem_resource);
>> bus = pci_scan_root_bus(NULL, 0, controller->ops,
>> controller, &resources);
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> controller->root_bus = bus;
>> controller->last_busno = bus->busn_res.end;
>> }
>> diff --git a/arch/tile/kernel/pci_gx.c b/arch/tile/kernel/pci_gx.c
>> index e39f9c5..3f8fb2c 100644
>> --- a/arch/tile/kernel/pci_gx.c
>> +++ b/arch/tile/kernel/pci_gx.c
>> @@ -889,6 +889,8 @@ int __init pcibios_init(void)
>> controller->first_busno = next_busno;
>> bus = pci_scan_root_bus(NULL, next_busno, controller->ops,
>> controller, &resources);
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> controller->root_bus = bus;
>> next_busno = bus->busn_res.end + 1;
>> }
>> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
>> index 7b20bcc..300d39e 100644
>> --- a/arch/x86/pci/common.c
>> +++ b/arch/x86/pci/common.c
>> @@ -475,6 +475,7 @@ void pcibios_scan_root(int busnum)
>> pci_free_resource_list(&resources);
>> kfree(sd);
>> }
>> + pci_bus_add_devices(bus);
>> }
>>
>> void __init pcibios_set_cache_line_size(void)
>> diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c
>> index 5b34033..f2ae64e 100644
>> --- a/arch/xtensa/kernel/pci.c
>> +++ b/arch/xtensa/kernel/pci.c
>> @@ -185,6 +185,8 @@ static int __init pcibios_init(void)
>> pci_controller_apertures(pci_ctrl, &resources);
>> bus = pci_scan_root_bus(NULL, pci_ctrl->first_busno,
>> pci_ctrl->ops, pci_ctrl, &resources);
>> + if (bus)
>> + pci_bus_add_devices(bus);
>> pci_ctrl->bus = bus;
>> pci_ctrl->last_busno = bus->busn_res.end;
>> if (next_busno <= pci_ctrl->last_busno)
>> diff --git a/drivers/pci/host/pci-xgene.c b/drivers/pci/host/pci-xgene.c
>> index 9ecabfa..c17afe5 100644
>> --- a/drivers/pci/host/pci-xgene.c
>> +++ b/drivers/pci/host/pci-xgene.c
>> @@ -635,6 +635,7 @@ static int xgene_pcie_probe_bridge(struct platform_device *pdev)
>> if (!bus)
>> return -ENOMEM;
>>
>> + pci_bus_add_devices(bus);
>> platform_set_drvdata(pdev, port);
>> return 0;
>> }
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 79775b5..2ab5a40 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -2084,7 +2084,6 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
>> if (!found)
>> pci_bus_update_busn_res_end(b, max);
>>
>> - pci_bus_add_devices(b);
>> return b;
>> }
>> EXPORT_SYMBOL(pci_scan_root_bus);
>> --
>> 1.7.1
>>
>> --
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>>
>
> .
>

--
Thanks!
Yijing