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USB: usb serial gadget smp related bug 

Adjust dev->dev_lock spinlock lock/unlock calls to be safe for SMP case.
Otherwise the following sequence may lead to a deadlock in SMP case:

gs_send()->usb_ep_queue()
	->(in case a request is satisfied immediatly) gs_write_complete()

for ex for pxa2xx_udc.c: 
usb_ep_queue()->pxa2xx_ep_queue()->write_fifo()->done()->gs_write_complete() 
(through req.complete pointer)

Signed-off-by: Eugeny S. Mints <emints@ru.mvista.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Eugeny S. Mints 2006-09-02 03:59:19 -07:00 committed by Greg Kroah-Hartman
parent 0e3c8c26c7
commit 80f8af0c59
1 changed files with 3 additions and 0 deletions
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3
drivers/usb/gadget/serial.c
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@ -1120,12 +1120,15 @@ static int gs_send(struct gs_dev *dev)
gs_debug_level(3, "gs_send: len=%d, 0x%2.2x 0x%2.2x 0x%2.2x ...\n", len, *((unsigned char *)req->buf), *((unsigned char *)req->buf+1), *((unsigned char *)req->buf+2));
list_del(&req_entry->re_entry);
req->length = len;
spin_unlock_irqrestore(&dev->dev_lock, flags);
if ((ret=usb_ep_queue(ep, req, GFP_ATOMIC))) {
printk(KERN_ERR
"gs_send: cannot queue read request, ret=%d\n",
ret);
spin_lock_irqsave(&dev->dev_lock, flags);
break;
}
spin_lock_irqsave(&dev->dev_lock, flags);
} else {
break;
}