linux-kernel - Re: [RFC PATCH v5 3/8] PCI: add a blocking notifier chain for PCI bus addition/removal

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Date:	Tue, 22 Jan 2013 00:18:55 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Yijing Wang <wangyijing@...wei.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Toshi Kani <toshi.kani@...com>,
	Myron Stowe <myron.stowe@...hat.com>
Subject: Re: [RFC PATCH v5 3/8] PCI: add a blocking notifier chain for PCI
 bus addition/removal

On 01/21/2013 07:54 AM, Rafael J. Wysocki wrote:
> On Saturday, January 19, 2013 12:07:41 AM Jiang Liu wrote:
>> When adding/removing a PCI bus, some other components want to be
snip
>> +
>> +void pci_bus_call_notifier(struct pci_bus *bus, unsigned long code)
>> +{
>> +	int ret;
>> +
>> +	ret = blocking_notifier_call_chain(&pci_bus_notifier_chain,
>> +					   code, bus);
>> +	WARN_ON(ret != NOTIFY_DONE && ret != NOTIFY_OK);
> 
> I'm not sure if this is a good idea.  WARN_ON() is quite a heavy tool.
Hi Rafael,
	How about WARN_ONCE() here?

> 
>> +}
>> +
>>  void pci_add_resource_offset(struct list_head *resources, struct resource *res,
>>  			     resource_size_t offset)
>>  {
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index ee21795..12e5447 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1033,6 +1033,18 @@ const struct pci_device_id *pci_match_id(const struct pci_device_id *ids,
>>  int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
>>  		    int pass);
>>  
>> +/*
>> + * All notifiers below get called with the target struct pci_bus *bus as
>> + * an argument.
>> + * Note: all PCI bus notifier must return success. Currently there's no
>> + * error handling if any notifier returns error code.
>> + */
>> +#define	PCI_NOTIFY_POST_BUS_ADD		0x00000001 /* PCI bus has been added */
>> +#define	PCI_NOTIFY_PRE_BUS_DEL		0x00000002 /* PCI bus will be deleted */
> 
> I would call them PCI_EVENT_BUS_ADDED and PCI_EVENT_BUS_REMOVE, respectively.
Sure, will use them in next version.

> 
>> +
>> +int pci_bus_register_notifier(struct notifier_block *nb);
>> +int pci_bus_unregister_notifier(struct notifier_block *nb);
>> +
>>  void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
>>  		  void *userdata);
>>  int pci_cfg_space_size_ext(struct pci_dev *dev);
> 
> Apart from the nitpicks above, looks good.
Thanks for review!

Regards!
Gerry
> 
> Thanks,
> Rafael
> 
> 

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