Re: [PATCH v2, part 1 8/9] PCI: make PCI host bridge/bus creating and destroying logic symmetric

[Liu Jiang <liuj97@gmail.com>]

On Mon 20 May 2013 02:35:31 PM CST, Gu Zheng wrote:
>
> On 05/14/2013 12:08 AM, Jiang Liu wrote:
>
>> This patch makes PCI host bridge/bus creating and destroying logic
>> symmetric by using device_initialize()/device_add()/device_del()/put_device()
>> pairs as discussed in thread at:
>> http://comments.gmane.org/gmane.linux.kernel.pci/22073
>>
>> It also fixes a bug in error recovery path in pci_create_root_bus()
>> which may kfree() an in-use host bridge object.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
>> Cc: Yinghai Lu <yinghai@kernel.org>
>> ---
>>   drivers/pci/probe.c  | 84 +++++++++++++++++++++++-----------------------------
>>   drivers/pci/remove.c |  3 +-
>>   2 files changed, 39 insertions(+), 48 deletions(-)
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index bc075a3..a2617c2 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -451,7 +451,7 @@ void pci_read_bridge_bases(struct pci_bus *child)
>>   	}
>>   }
>>
>> -static struct pci_bus * pci_alloc_bus(void)
>> +static struct pci_bus *pci_alloc_bus(struct pci_ops *ops, void *sd, int bus)
>>   {
>>   	struct pci_bus *b;
>>
>> @@ -464,10 +464,32 @@ static struct pci_bus * pci_alloc_bus(void)
>>   		INIT_LIST_HEAD(&b->resources);
>>   		b->max_bus_speed = PCI_SPEED_UNKNOWN;
>>   		b->cur_bus_speed = PCI_SPEED_UNKNOWN;
>> +		b->sysdata = sd;
>> +		b->ops = ops;
>> +		b->number = bus;
>> +		b->busn_res.start = bus;
>> +		b->busn_res.end = 0xff;
>> +		b->busn_res.flags = IORESOURCE_BUS;
>> +		b->dev.class = &pcibus_class;
>> +		dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
>> +		device_initialize(&b->dev);
>>   	}
>> +
>>   	return b;
>>   }
>>
>> +static void pci_release_host_bridge_dev(struct device *dev)
>> +{
>> +	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
>> +
>> +	if (bridge->release_fn)
>> +		bridge->release_fn(bridge);
>> +
>> +	pci_free_resource_list(&bridge->windows);
>> +
>> +	kfree(bridge);
>> +}
>> +
>>   static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
>>   {
>>   	struct pci_host_bridge *bridge;
>> @@ -476,6 +498,10 @@ static struct pci_host_bridge *pci_alloc_host_bridge(struct pci_bus *b)
>>   	if (bridge) {
>>   		INIT_LIST_HEAD(&bridge->windows);
>>   		bridge->bus = b;
>> +		bridge->dev.release = pci_release_host_bridge_dev;
>> +		dev_set_name(&bridge->dev, "pci%04x:%02x",
>> +			     pci_domain_nr(b), b->number);
>> +		device_initialize(&bridge->dev);
>>   	}
>>
>>   	return bridge;
>> @@ -628,28 +654,13 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>>   	/*
>>   	 * Allocate a new bus, and inherit stuff from the parent..
>>   	 */
>> -	child = pci_alloc_bus();
>> +	child = pci_alloc_bus(parent->ops, parent->sysdata, busnr);
>>   	if (!child)
>>   		return NULL;
>>
>>   	child->parent = parent;
>> -	child->ops = parent->ops;
>> -	child->sysdata = parent->sysdata;
>>   	child->bus_flags = parent->bus_flags;
>> -
>> -	/* initialize some portions of the bus device, but don't register it
>> -	 * now as the parent is not properly set up yet.
>> -	 */
>> -	child->dev.class = &pcibus_class;
>> -	dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
>> -
>> -	/*
>> -	 * Set up the primary, secondary and subordinate
>> -	 * bus numbers.
>> -	 */
>> -	child->number = child->busn_res.start = busnr;
>>   	child->primary = parent->busn_res.start;
>> -	child->busn_res.end = 0xff;
>>
>>   	if (!bridge) {
>>   		child->dev.parent = parent->bridge;
>> @@ -670,7 +681,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
>>   	bridge->subordinate = child;
>>
>>   add_dev:
>> -	ret = device_register(&child->dev);
>> +	ret = device_add(&child->dev);
>>   	WARN_ON(ret < 0);
>>
>>   	pcibios_add_bus(child);
>> @@ -1190,18 +1201,6 @@ int pci_cfg_space_size(struct pci_dev *dev)
>>   	return PCI_CFG_SPACE_SIZE;
>>   }
>>
>> -static void pci_release_bus_bridge_dev(struct device *dev)
>> -{
>> -	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
>> -
>> -	if (bridge->release_fn)
>> -		bridge->release_fn(bridge);
>> -
>> -	pci_free_resource_list(&bridge->windows);
>> -
>> -	kfree(bridge);
>> -}
>> -
>>   struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
>>   {
>>   	struct pci_dev *dev;
>> @@ -1688,13 +1687,10 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>   	char bus_addr[64];
>>   	char *fmt;
>>
>> -	b = pci_alloc_bus();
>> +	b = pci_alloc_bus(ops, sysdata, bus);
>>   	if (!b)
>>   		return NULL;
>>
>> -	b->sysdata = sysdata;
>> -	b->ops = ops;
>> -	b->number = b->busn_res.start = bus;
>>   	b2 = pci_find_bus(pci_domain_nr(b), bus);
>>   	if (b2) {
>>   		/* If we already got to this bus through a different bridge, ignore it */
>> @@ -1706,27 +1702,22 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>   	if (!bridge)
>>   		goto err_out;
>>
>> -	bridge->dev.parent = parent;
>> -	bridge->dev.release = pci_release_bus_bridge_dev;
>> -	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>>   	error = pcibios_root_bridge_prepare(bridge);
>>   	if (error)
>>   		goto bridge_dev_reg_err;
>>
>> -	error = device_register(&bridge->dev);
>> +	bridge->dev.parent = parent;
>> +	error = device_add(&bridge->dev);
>>   	if (error)
>>   		goto bridge_dev_reg_err;
>> +
>>   	b->bridge = get_device(&bridge->dev);
>>   	device_enable_async_suspend(b->bridge);
>>   	pci_set_bus_of_node(b);
>> -
>>   	if (!parent)
>>   		set_dev_node(b->bridge, pcibus_to_node(b));
>> -
>> -	b->dev.class = &pcibus_class;
>>   	b->dev.parent = b->bridge;
>> -	dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
>> -	error = device_register(&b->dev);
>> +	error = device_add(&b->dev);
>>   	if (error)
>>   		goto class_dev_reg_err;
>>
>> @@ -1769,12 +1760,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>>   	return b;
>>
>>   class_dev_reg_err:
>> -	put_device(&bridge->dev);
>> -	device_unregister(&bridge->dev);
>> +	device_del(&bridge->dev);
>>   bridge_dev_reg_err:
>> -	kfree(bridge);
>> +	put_device(&bridge->dev);
>>   err_out:
>> -	kfree(b);
>> +	put_device(&b->dev);
>>   	return NULL;
>>   }
>
> Hi Jiang,
> 	I think the changes here may lead to memleak, doesn't it?
>
> Best regards,
> Gu
Hi Gu Zheng,
     I have checked to code again and didn't find the memory leakage 
issue.
Could you please help to give more hints about the leakage?
Thanks!
Gerry

>
>>
>> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
>> index 8fc54b7..b0ce875 100644
>> --- a/drivers/pci/remove.c
>> +++ b/drivers/pci/remove.c
>> @@ -52,7 +52,8 @@ void pci_remove_bus(struct pci_bus *bus)
>>   	up_write(&pci_bus_sem);
>>   	pci_remove_legacy_files(bus);
>>   	pcibios_remove_bus(bus);
>> -	device_unregister(&bus->dev);
>> +	device_del(&bus->dev);
>> +	put_device(&bus->dev);
>>   }
>>   EXPORT_SYMBOL(pci_remove_bus);
>>
>
>