isdn: mISDN: use irqsave() in USB's complete callback

The USB completion callback does not disable interrupts while acquiring
the ->lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/hfcsusb.c

@@ -819,6 +819,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 	int		fifon = fifo->fifonum;
 	int		i;
 	int		hdlc = 0;
+	unsigned long	flags;
 
 	if (debug & DBG_HFC_CALL_TRACE)
 		printk(KERN_DEBUG "%s: %s: fifo(%i) len(%i) "
@@ -835,7 +836,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 		return;
 	}
 
-	spin_lock(&hw->lock);
+	spin_lock_irqsave(&hw->lock, flags);
 	if (fifo->dch) {
 		rx_skb = fifo->dch->rx_skb;
 		maxlen = fifo->dch->maxlen;
@@ -844,7 +845,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 	if (fifo->bch) {
 		if (test_bit(FLG_RX_OFF, &fifo->bch->Flags)) {
 			fifo->bch->dropcnt += len;
-			spin_unlock(&hw->lock);
+			spin_unlock_irqrestore(&hw->lock, flags);
 			return;
 		}
 		maxlen = bchannel_get_rxbuf(fifo->bch, len);
@@ -854,7 +855,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 				skb_trim(rx_skb, 0);
 			pr_warning("%s.B%d: No bufferspace for %d bytes\n",
 				   hw->name, fifo->bch->nr, len);
-			spin_unlock(&hw->lock);
+			spin_unlock_irqrestore(&hw->lock, flags);
 			return;
 		}
 		maxlen = fifo->bch->maxlen;
@@ -878,7 +879,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 			} else {
 				printk(KERN_DEBUG "%s: %s: No mem for rx_skb\n",
 				       hw->name, __func__);
-				spin_unlock(&hw->lock);
+				spin_unlock_irqrestore(&hw->lock, flags);
 				return;
 			}
 		}
@@ -888,7 +889,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 			       "for fifo(%d) HFCUSB_D_RX\n",
 			       hw->name, __func__, fifon);
 			skb_trim(rx_skb, 0);
-			spin_unlock(&hw->lock);
+			spin_unlock_irqrestore(&hw->lock, flags);
 			return;
 		}
 	}
@@ -942,7 +943,7 @@ hfcsusb_rx_frame(struct usb_fifo *fifo, __u8 *data, unsigned int len,
 		/* deliver transparent data to layer2 */
 		recv_Bchannel(fifo->bch, MISDN_ID_ANY, false);
 	}
-	spin_unlock(&hw->lock);
+	spin_unlock_irqrestore(&hw->lock, flags);
 }
 
 static void
@@ -979,18 +980,19 @@ rx_iso_complete(struct urb *urb)
 	__u8 *buf;
 	static __u8 eof[8];
 	__u8 s0_state;
+	unsigned long flags;
 
 	fifon = fifo->fifonum;
 	status = urb->status;
 
-	spin_lock(&hw->lock);
+	spin_lock_irqsave(&hw->lock, flags);
 	if (fifo->stop_gracefull) {
 		fifo->stop_gracefull = 0;
 		fifo->active = 0;
-		spin_unlock(&hw->lock);
+		spin_unlock_irqrestore(&hw->lock, flags);
 		return;
 	}
-	spin_unlock(&hw->lock);
+	spin_unlock_irqrestore(&hw->lock, flags);
 
 	/*
 	 * ISO transfer only partially completed,
@@ -1096,15 +1098,16 @@ rx_int_complete(struct urb *urb)
 	struct usb_fifo *fifo = (struct usb_fifo *) urb->context;
 	struct hfcsusb *hw = fifo->hw;
 	static __u8 eof[8];
+	unsigned long flags;
 
-	spin_lock(&hw->lock);
+	spin_lock_irqsave(&hw->lock, flags);
 	if (fifo->stop_gracefull) {
 		fifo->stop_gracefull = 0;
 		fifo->active = 0;
-		spin_unlock(&hw->lock);
+		spin_unlock_irqrestore(&hw->lock, flags);
 		return;
 	}
-	spin_unlock(&hw->lock);
+	spin_unlock_irqrestore(&hw->lock, flags);
 
 	fifon = fifo->fifonum;
 	if ((!fifo->active) || (urb->status)) {
@@ -1172,12 +1175,13 @@ tx_iso_complete(struct urb *urb)
 	int *tx_idx;
 	int frame_complete, fifon, status, fillempty = 0;
 	__u8 threshbit, *p;
+	unsigned long flags;
 
-	spin_lock(&hw->lock);
+	spin_lock_irqsave(&hw->lock, flags);
 	if (fifo->stop_gracefull) {
 		fifo->stop_gracefull = 0;
 		fifo->active = 0;
-		spin_unlock(&hw->lock);
+		spin_unlock_irqrestore(&hw->lock, flags);
 		return;
 	}
 
@@ -1195,7 +1199,7 @@ tx_iso_complete(struct urb *urb)
 	} else {
 		printk(KERN_DEBUG "%s: %s: neither BCH nor DCH\n",
 		       hw->name, __func__);
-		spin_unlock(&hw->lock);
+		spin_unlock_irqrestore(&hw->lock, flags);
 		return;
 	}
 
@@ -1375,7 +1379,7 @@ tx_iso_complete(struct urb *urb)
 			       hw->name, __func__,
 			       symbolic(urb_errlist, status), status, fifon);
 	}
-	spin_unlock(&hw->lock);
+	spin_unlock_irqrestore(&hw->lock, flags);
 }
 
 /*