[PATCH 4.2.y-ckt 37/70] usb: renesas_usbhs: fix to avoid using a disabled ep in usbhsg_queue_done()

[Kamal Mostafa]

4.2.8-ckt8 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

commit 4fccb0767fdbdb781a9c5b5c15ee7b219443c89d upstream.

This patch fixes an issue that usbhsg_queue_done() may cause kernel
panic when dma callback is running and usb_ep_disable() is called
by interrupt handler. (Especially, we can reproduce this issue using
g_audio with usb-dmac driver.)

For example of a flow:
 usbhsf_dma_complete (on tasklet)
  --> usbhsf_pkt_handler (on tasklet)
   --> usbhsg_queue_done (on tasklet)
    *** interrupt happened and usb_ep_disable() is called ***
    --> usbhsg_queue_pop (on tasklet)
     Then, oops happened.

Fixes: e73a989 ("usb: renesas_usbhs: add DMAEngine support")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 drivers/usb/renesas_usbhs/mod_gadget.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c
index dc2aa32..0465296 100644
--- a/drivers/usb/renesas_usbhs/mod_gadget.c
+++ b/drivers/usb/renesas_usbhs/mod_gadget.c
@@ -154,10 +154,14 @@ static void usbhsg_queue_done(struct usbhs_priv *priv, struct usbhs_pkt *pkt)
 	struct usbhs_pipe *pipe = pkt->pipe;
 	struct usbhsg_uep *uep = usbhsg_pipe_to_uep(pipe);
 	struct usbhsg_request *ureq = usbhsg_pkt_to_ureq(pkt);
+	unsigned long flags;
 
 	ureq->req.actual = pkt->actual;
 
-	usbhsg_queue_pop(uep, ureq, 0);
+	usbhs_lock(priv, flags);
+	if (uep)
+		__usbhsg_queue_pop(uep, ureq, 0);
+	usbhs_unlock(priv, flags);
 }
 
 static void usbhsg_queue_push(struct usbhsg_uep *uep,
-- 
2.7.4