Re: [PATCH v12 06/12] PCI: Create pci_host_bridge before its associated bus in pci_create_root_bus.

[Bjorn Helgaas]

On Thu, Sep 25, 2014 at 12:15 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Tue, Sep 23, 2014 at 12:01 PM, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote:
>> Before commit 7b5436635800 the pci_host_bridge was created before the root bus.
>> As that commit has added a needless dependency on the bus for pci_alloc_host_bridge()
>> the creation order has been changed for no good reason. Revert the order of
>> creation as we are going to depend on the pci_host_bridge structure to retrieve the
>> domain number of the root bus.
>>
>> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>> Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
>> Acked-by: Grant Likely <grant.likely@xxxxxxxxxx>
>> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Tested-by: Tanmay Inamdar <tinamdar@xxxxxxx>
>> ---
>>  drivers/pci/probe.c | 32 +++++++++++++++++---------------
>>  1 file changed, 17 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index e3cf8a2..5ff72ec 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -515,7 +515,7 @@ static void pci_release_host_bridge_dev(struct device *dev)
>>         kfree(bridge);
>>  }
>>
>> -static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
>> +static struct pci_host_bridge *pci_alloc_host_bridge(void)
>>  {
>>         struct pci_host_bridge *bridge;
>>
>> @@ -524,7 +524,8 @@ static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
>>                 return NULL;
>>
>>         INIT_LIST_HEAD(&bridge->windows);
>> -       bridge->bus = b;
>> +       bridge->dev.release = pci_release_host_bridge_dev;
>> +
>>         return bridge;
>>  }
>>
>> @@ -1761,9 +1762,15 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>         char bus_addr[64];
>>         char *fmt;
>>
>> +       bridge = pci_alloc_host_bridge();
>> +       if (!bridge)
>> +               return NULL;
>> +
>> +       bridge->dev.parent = parent;
>> +
>>         b = pci_alloc_bus();
>>         if (!b)
>> -               return NULL;
>> +               goto err_out;
>>
>>         b->sysdata = sysdata;
>>         b->ops = ops;
>> @@ -1772,26 +1779,19 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>         if (b2) {
>>                 /* If we already got to this bus through a different bridge, ignore it */
>>                 dev_dbg(&b2->dev, "bus already known\n");
>> -               goto err_out;
>> +               goto err_bus_out;
>>         }
>>
>> -       bridge = pci_alloc_host_bridge(b);
>> -       if (!bridge)
>> -               goto err_out;
>> -
>> -       bridge->dev.parent = parent;
>> -       bridge->dev.release = pci_release_host_bridge_dev;
>> +       bridge->bus = b;
>>         dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>>         error = pcibios_root_bridge_prepare(bridge);
>> -       if (error) {
>> -               kfree(bridge);
>> +       if (error)
>>                 goto err_out;
>> -       }
>>
>>         error = device_register(&bridge->dev);
>>         if (error) {
>>                 put_device(&bridge->dev);
>> -               goto err_out;
>> +               goto err_bus_out;
>>         }
>>         b->bridge = get_device(&bridge->dev);
>>         device_enable_async_suspend(b->bridge);
>> @@ -1848,8 +1848,10 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>  class_dev_reg_err:
>>         put_device(&bridge->dev);
>>         device_unregister(&bridge->dev);
>> -err_out:
>> +err_bus_out:
>>         kfree(b);
>> +err_out:
>> +       kfree(bridge);
>>         return NULL;
>>  }
>
> Hi Bjorn,
>
> Noticed that you put this one into pci/next.
>
> This patch has problem for the class_dev_reg_err path.
> as device_unregister(&bridge->dev) will trigger pci_release_host_bridge_dev.
> So will have double free for bridge or else.
>
> Please drop this patch from pci/next.
>
> Also looks strange that the patch have long CC list, but just omit me
> and Jiang Liu that
> touched those code before.

Thanks for noticing that.  I was concerned, but couldn't remember the details.

I dropped this patch and the subsequent ones from pci/host and rebased
my "next" branch.

Sorry I didn't notice you weren't on the CC list.

Bjorn
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