On Wed, 20 Jun 2012, Sergei Shtylyov wrote:
> Hello.
>
> On 20-06-2012 6:06, Lan Tianyu wrote:
>
> >>> -struct dev_state {
> >>> - struct list_head list; /* state list */
> >>> - struct usb_device *dev;
> >>> - struct file *file;
> >>> - spinlock_t lock; /* protects the async urb lists */
> >>> - struct list_head async_pending;
> >>> - struct list_head async_completed;
> >>> - wait_queue_head_t wait; /* wake up if a request completed */
> >>> - unsigned int discsignr;
> >>> - struct pid *disc_pid;
> >>> - const struct cred *cred;
> >>> - void __user *disccontext;
> >>> - unsigned long ifclaimed;
> >>> - u32 secid;
> >>> - u32 disabled_bulk_eps;
> >>> -};
>
> >> Please don't move the definition of this structure. It is private to
> >> devio.c.
>
> > But the struct dev_state will be used in the hub.c.
>
> Only to declare the pointer to that structure. We don't need to know its
> members for that.
Right. To put it another way, hub.c doesn't use struct dev_state -- it
uses only _pointers_ to struct dev_state, which is quite a different
thing.
> > Is there
> > other ways to do that without moving the definition of struct
> > dev_state to a head file?
>
> Yes, of course: incomplete declaration of the structure in hub.c:
>
> struct dev_state;
Even that isn't needed. The compiler will realize that dev_state is an
incomplete structure the first time it sees
struct dev_state *owner;
Alan Stern
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