Re: [RFC]confusions about 'struct' define

[Gaurav Jain <gjainroorkee@xxxxxxxxx>]

Those are forward declarations as they are being used in defining struct bus_attribute. It's nothing special about GNU-C. That's the case for ANSI-C too. Pretty standard.

On Wed, May 30, 2012 at 10:20 PM, harryxiyou <harryxiyou@xxxxxxxxx> wrote:

Hi guys,

When I read the linux/device.h file for some device driver usage, i find some
confusions like following.

$ head -60 device.h
[...]

struct device;
struct device_private;
struct device_driver;
struct driver_private;
struct module;
struct class;
struct subsys_private;
struct bus_type;
struct device_node;
struct iommu_ops;

struct bus_attribute {
       struct attribute        attr;
       ssize_t (*show)(struct bus_type *bus, char *buf);
       ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
};
[...]

I have never seen struct define like

"struct device;
struct device_private;
struct device_driver;
[...]
struct device_node;
struct iommu_ops;"

The common define is like this

"struct a{
  int a;
  int b;
[...]
}"

Is this just struct declaration or some extension about gcc? Cloud
anyone give me
some explanations?
Thanks in advance ;-)

Note: my kernel version is 3.0 around.

--
Thanks
Harry Wei

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--

Gaurav Jain

Associate Software Engineer

VxVM Escalations Team, SAMG

Symantec Software India Pvt. Ltd.

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