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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index 00521f1..cf3fc91 100644 (file)
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -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) {

diff --git a/drivers/usb/storage/usb.h b/drivers/usb/storage/usb.h
index 6dac1ff..6445665 100644 (file)
--- a/drivers/usb/storage/usb.h
+++ b/drivers/usb/storage/usb.h
@@ -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      */