read / write / close sync for device files

[Greg KH]

On Mon, Jul 04, 2011 at 06:13:49PM +0530, Amit Nagal wrote:
> Hi ,
> 
> if  a application is  doing read /write I/O with a  usb device ,  in 2
> different threads in userspace ,

What type of USB device?

> and at usb disconnect event ,  read thread returns with error and
> application calls close() subsequently without waiting for write
> thread to finish .
> 
> Do  the VFS upper layers  maintain locks that  take care that until
> both read and write methods in usb driver donot finish and return with
> error in kernel space
> 
> close will pend and usb driver release method will not be called ?

No, close will succeed, and then all will be cleaned up properly.

Try it yourself and see :)

greg k-h