SCENARIO: In host mode, I am trying to copy some files from the pendrive to the sdcard or vice-versa using the astro file manager.During the file transfer, if I disconnect the pendrive,and then reconnect it back,it is observed that re-enumeration is not taking place. ANALYSIS: >From the stack trace,we see that there are 2 main threads involved: 1) usb-storage thread: When file transfer is in progress,the pendrive is removed.In this context,usb_sg_wait() function is waiting infinitely for the IO to complete (wait_for_completion(&io->complete)). Since the drive is removed,this wait never completes. 2) khubd thread On disconnecting the pendrive, during the device delete operation, usb_stor_disconnect() function is called which is trying to release the storage resources and then tries to stop the usb-storage thread via kthread_stop(). The usb_storage thread is not listening on kthread_should_stop as it is waiting infinitely on usb_sg_wait(). Hence the hub thread is also blocked as it tries to stop the storage thread. QUESTIONS: 1)Why is the wait_for_completion(&io->complete) not a timed wait? (* After adding a timeout of 5 seconds,this issue is no longer seen , the pendrive enumerates each time) 2)If we do put a timed wait,what should be the ideal timeout value? Kindly provide appropriate feedback. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
