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usb: musb: host: fix for musb_start_urb Oops 

when using musb_urb_enqueue to submit three urbs to the same endpoint, when
hep->hcpriv is NULL, qh will be allocated when the first urb is completed.

When the IRQ completes the next two urbs, qh->hep->hcpriv will be set to NULL.
Now the second urb get musb->lock and executes musb_schedule(), but
next_urb(qh) is NULL, so musb_start_urb will Oops.

[ balbi@ti.com : practically rewrote commit log so it makes sense ]

Signed-off-by: mayuzheng <myz147@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
yuzheng ma 2012-08-15 16:11:40 +08:00 committed by Felipe Balbi
parent 3b9c1c5ba7
commit 3067779b15
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/musb/musb_host.c
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@ -2049,7 +2049,7 @@ static int musb_urb_enqueue(
* we only have work to do in the former case.
*/
spin_lock_irqsave(&musb->lock, flags);
if (hep->hcpriv) {
if (hep->hcpriv || !next_urb(qh)) {
/* some concurrent activity submitted another urb to hep...
* odd, rare, error prone, but legal.
*/