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Commit ed76cacb authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: usb-storage: use kthread_stop() for the control thread 



This patch (as923) makes usb-storage's control thread use
kthread_should_stop()/kthread_stop().  The scanning thread can't be
similarly converted until the core kthread implementation allows
threads to call do_exit().

The advantage of this change is that we can now be certain the control
thread has terminated before storage_disconnect() returns.  This will
simplify the locking requirements when autosuspend support is added.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarMatthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 3fc154b6

drivers/usb/storage/usb.c

+13 −25
Original line number Diff line number Diff line
@@ -425,23 +425,15 @@ SkipForAbort: 
		mutex_unlock(&us->dev_mutex);

	} /* for (;;) */



	scsi_host_put(host);



	/* notify the exit routine that we're actually exiting now 

	 *

	 * complete()/wait_for_completion() is similar to up()/down(),

	 * except that complete() is safe in the case where the structure

	 * is getting deleted in a parallel mode of execution (i.e. just

	 * after the down() -- that's necessary for the thread-shutdown

	 * case.

	 *

	 * complete_and_exit() goes even further than this -- it is safe in

	 * the case that the thread of the caller is going away (not just

	 * the structure) -- this is necessary for the module-remove case.

	 * This is important in preemption kernels, which transfer the flow

	 * of execution immediately upon a complete().

	 */

	complete_and_exit(&threads_gone, 0);

	/* Wait until we are told to stop */

	for (;;) {

		set_current_state(TASK_INTERRUPTIBLE);

		if (kthread_should_stop())

			break;

		schedule();

	}

	__set_current_state(TASK_RUNNING);

	return 0;

}	



/***********************************************************************
@@ -809,19 +801,13 @@ static int usb_stor_acquire_resources(struct us_data *us) 
	}



	/* Start up our control thread */

	th = kthread_create(usb_stor_control_thread, us, "usb-storage");

	th = kthread_run(usb_stor_control_thread, us, "usb-storage");

	if (IS_ERR(th)) {

		printk(KERN_WARNING USB_STORAGE 

		       "Unable to start control thread\n");

		return PTR_ERR(th);

	}



	/* Take a reference to the host for the control thread and

	 * count it among all the threads we have launched.  Then

	 * start it up. */

	scsi_host_get(us_to_host(us));

	atomic_inc(&total_threads);

	wake_up_process(th);

	us->ctl_thread = th;



	return 0;

}
@@ -838,6 +824,8 @@ static void usb_stor_release_resources(struct us_data *us) 
	US_DEBUGP("-- sending exit command to thread\n");

	set_bit(US_FLIDX_DISCONNECTING, &us->flags);

	up(&us->sema);

	if (us->ctl_thread)

		kthread_stop(us->ctl_thread);



	/* Call the destructor routine, if it exists */

	if (us->extra_destructor) {

drivers/usb/storage/usb.h

+1 −0
Original line number Diff line number Diff line
@@ -144,6 +144,7 @@ struct us_data { 
	unsigned char		*sensebuf;	 /* sense data buffer	 */

	dma_addr_t		cr_dma;		 /* buffer DMA addresses */

	dma_addr_t		iobuf_dma;

	struct task_struct	*ctl_thread;	 /* the control thread   */



	/* mutual exclusion and synchronization structures */

	struct semaphore	sema;		 /* to sleep thread on	    */