On 2012年06月20日 22:43, Alan Stern wrote:
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;
hi all:
Thanks for your help. I find declaration of "struct dev_state" is
necessary and it should be in the driver/usb/core/usb.h. Because the declaration
of usb_hub_claim_port(), usb_hub_release_port() and usb_hub_release_all_ports()
in the driver/usb/core/usb.h also needs the declaration of "struct dev_state".
Alan Stern
--
Best Regards
Tianyu Lan
linux kernel enabling team
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