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USB: usb-storage: use kthread_stop() for the control thread

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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>
This commit is contained in:
Alan Stern 2007-06-07 17:12:25 -04:00 committed by Greg Kroah-Hartman
parent 3fc154b6b8
commit ed76cacbea
2 changed files with 14 additions and 25 deletions
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38
drivers/usb/storage/usb.c
View File

@ -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) {

1
drivers/usb/storage/usb.h
View File

@ -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 */