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
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -425,23 +425,15 @@
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 @@
}
/* 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 @@
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
--- a/drivers/usb/storage/usb.h
+++ b/drivers/usb/storage/usb.h
@@ -144,6 +144,7 @@
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 */