[IRDA]: irda-usb bug fixes

This patch fixes 2 bugs in the USB-IrDA code.

The first one is a buffer overrun in the RX path. We are now using
IRDA_SKB_MAX_MTU when initializing the Rx URB.

The second one is a potential stack recursion when unplugging the USB
dongle.  It seems that first we get the Rx URB with a generic error
code, and after a while the Rx URB comes again with a "disconnect"
error code.  Since we are resubmitting the Rx URB immediately after
receiving the first error one, we might enter an endless loop.

When getting an error Rx URB, the patch defers the Rx URB resubmitting
so that it gives us a chance to catch the disconnect one, in case the
dongle has juts been unplugged.

Tested against 2.6.16-rc2.

Patch from Jean Tourrilhes

Signed-off-by: Jean Tourrilhes <jt@hpl.hp.com>
Signed-off-by: Samuel Ortiz <samuel.ortiz@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/irda/irda-usb.c

@@ -108,6 +108,7 @@ static void irda_usb_close(struct irda_usb_cb *self);
 static void speed_bulk_callback(struct urb *urb, struct pt_regs *regs);
 static void write_bulk_callback(struct urb *urb, struct pt_regs *regs);
 static void irda_usb_receive(struct urb *urb, struct pt_regs *regs);
+static void irda_usb_rx_defer_expired(unsigned long data);
 static int irda_usb_net_open(struct net_device *dev);
 static int irda_usb_net_close(struct net_device *dev);
 static int irda_usb_net_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
@@ -677,6 +678,12 @@ static void irda_usb_net_timeout(struct net_device *netdev)
  * on the interrupt pipe and hang the Rx URB only when an interrupt is
  * received.
  * Jean II
+ *
+ * Note : don't read the above as what we are currently doing, but as
+ * something we could do with KC dongle. Also don't forget that the
+ * interrupt pipe is not part of the original standard, so this would
+ * need to be optional...
+ * Jean II
  */
 
 /*------------------------------------------------------------------*/
@@ -704,10 +711,8 @@ static void irda_usb_submit(struct irda_usb_cb *self, struct sk_buff *skb, struc
 	/* Reinitialize URB */
 	usb_fill_bulk_urb(urb, self->usbdev, 
 		      usb_rcvbulkpipe(self->usbdev, self->bulk_in_ep), 
-		      skb->data, skb->truesize,
+		      skb->data, IRDA_SKB_MAX_MTU,
                       irda_usb_receive, skb);
-	/* Note : unlink *must* be synchronous because of the code in 
-	 * irda_usb_net_close() -> free the skb - Jean II */
 	urb->status = 0;
 
 	/* Can be called from irda_usb_receive (irq handler) -> GFP_ATOMIC */
@@ -734,6 +739,7 @@ static void irda_usb_receive(struct urb *urb, struct pt_regs *regs)
 	struct irda_skb_cb *cb;
 	struct sk_buff *newskb;
 	struct sk_buff *dataskb;
+	struct urb *next_urb;
 	int		docopy;
 
 	IRDA_DEBUG(2, "%s(), len=%d\n", __FUNCTION__, urb->actual_length);
@@ -755,20 +761,37 @@ static void irda_usb_receive(struct urb *urb, struct pt_regs *regs)
 	if (urb->status != 0) {
 		switch (urb->status) {
 		case -EILSEQ:
-			self->stats.rx_errors++;
 			self->stats.rx_crc_errors++;	
-			break;
+			/* Also precursor to a hot-unplug on UHCI. */
+			/* Fallthrough... */
 		case -ECONNRESET:		/* -104 */
-			IRDA_DEBUG(0, "%s(), Connection Reset (-104), transfer_flags 0x%04X \n", __FUNCTION__, urb->transfer_flags);
+			/* Random error, if I remember correctly */
 			/* uhci_cleanup_unlink() is going to kill the Rx
 			 * URB just after we return. No problem, at this
 			 * point the URB will be idle ;-) - Jean II */
-			break;
+		case -ESHUTDOWN:		/* -108 */
+			/* That's usually a hot-unplug. Submit will fail... */
+		case -ETIMEDOUT:		/* -110 */
+			/* Usually precursor to a hot-unplug on OHCI. */
 		default:
-			IRDA_DEBUG(0, "%s(), RX status %d,transfer_flags 0x%04X \n", __FUNCTION__, urb->status, urb->transfer_flags);
+			self->stats.rx_errors++;
+			IRDA_DEBUG(0, "%s(), RX status %d, transfer_flags 0x%04X \n", __FUNCTION__, urb->status, urb->transfer_flags);
 			break;
 		}
-		goto done;
+		/* If we received an error, we don't want to resubmit the
+		 * Rx URB straight away but to give the USB layer a little
+		 * bit of breathing room.
+		 * We are in the USB thread context, therefore there is a
+		 * danger of recursion (new URB we submit fails, we come
+		 * back here).
+		 * With recent USB stack (2.6.15+), I'm seeing that on
+		 * hot unplug of the dongle...
+		 * Lowest effective timer is 10ms...
+		 * Jean II */
+		self->rx_defer_timer.function = &irda_usb_rx_defer_expired;
+		self->rx_defer_timer.data = (unsigned long) urb;
+		mod_timer(&self->rx_defer_timer, jiffies + (10 * HZ / 1000));
+		return;
 	}
 	
 	/* Check for empty frames */
@@ -845,13 +868,45 @@ done:
 	 * idle slot....
 	 * Jean II */
 	/* Note : with this scheme, we could submit the idle URB before
-	 * processing the Rx URB. Another time... Jean II */
+	 * processing the Rx URB. I don't think it would buy us anything as
+	 * we are running in the USB thread context. Jean II */
+	next_urb = self->idle_rx_urb;
 
-	/* Submit the idle URB to replace the URB we've just received */
-	irda_usb_submit(self, skb, self->idle_rx_urb);
 	/* Recycle Rx URB : Now, the idle URB is the present one */
 	urb->context = NULL;
 	self->idle_rx_urb = urb;
+
+	/* Submit the idle URB to replace the URB we've just received.
+	 * Do it last to avoid race conditions... Jean II */
+	irda_usb_submit(self, skb, next_urb);
+}
+
+/*------------------------------------------------------------------*/
+/*
+ * In case of errors, we want the USB layer to have time to recover.
+ * Now, it is time to resubmit ouur Rx URB...
+ */
+static void irda_usb_rx_defer_expired(unsigned long data)
+{
+	struct urb *urb = (struct urb *) data;
+	struct sk_buff *skb = (struct sk_buff *) urb->context;
+	struct irda_usb_cb *self; 
+	struct irda_skb_cb *cb;
+	struct urb *next_urb;
+
+	IRDA_DEBUG(2, "%s()\n", __FUNCTION__);
+
+	/* Find ourselves */
+	cb = (struct irda_skb_cb *) skb->cb;
+	IRDA_ASSERT(cb != NULL, return;);
+	self = (struct irda_usb_cb *) cb->context;
+	IRDA_ASSERT(self != NULL, return;);
+
+	/* Same stuff as when Rx is done, see above... */
+	next_urb = self->idle_rx_urb;
+	urb->context = NULL;
+	self->idle_rx_urb = urb;
+	irda_usb_submit(self, skb, next_urb);
 }
 
 /*------------------------------------------------------------------*/
@@ -990,6 +1045,9 @@ static int irda_usb_net_close(struct net_device *netdev)
 	/* Stop network Tx queue */
 	netif_stop_queue(netdev);
 
+	/* Kill defered Rx URB */
+	del_timer(&self->rx_defer_timer);
+
 	/* Deallocate all the Rx path buffers (URBs and skb) */
 	for (i = 0; i < IU_MAX_RX_URBS; i++) {
 		struct urb *urb = self->rx_urb[i];
@@ -1365,6 +1423,7 @@ static int irda_usb_probe(struct usb_interface *intf,
 	self = net->priv;
 	self->netdev = net;
 	spin_lock_init(&self->lock);
+	init_timer(&self->rx_defer_timer);
 
 	/* Create all of the needed urbs */
 	for (i = 0; i < IU_MAX_RX_URBS; i++) {
@@ -1498,6 +1557,9 @@ static void irda_usb_disconnect(struct usb_interface *intf)
 	 * This will stop/desactivate the Tx path. - Jean II */
 	self->present = 0;
 
+	/* Kill defered Rx URB */
+	del_timer(&self->rx_defer_timer);
+
 	/* We need to have irq enabled to unlink the URBs. That's OK,
 	 * at this point the Tx path is gone - Jean II */
 	spin_unlock_irqrestore(&self->lock, flags);
@@ -1507,11 +1569,11 @@ static void irda_usb_disconnect(struct usb_interface *intf)
 		/* Accept no more transmissions */
 		/*netif_device_detach(self->netdev);*/
 		netif_stop_queue(self->netdev);
-		/* Stop all the receive URBs */
+		/* Stop all the receive URBs. Must be synchronous. */
 		for (i = 0; i < IU_MAX_RX_URBS; i++)
 			usb_kill_urb(self->rx_urb[i]);
 		/* Cancel Tx and speed URB.
-		 * Toggle flags to make sure it's synchronous. */
+		 * Make sure it's synchronous to avoid races. */
 		usb_kill_urb(self->tx_urb);
 		usb_kill_urb(self->speed_urb);
 	}

drivers/net/irda/irda-usb.h

@@ -136,8 +136,6 @@ struct irda_usb_cb {
 	__u16 bulk_out_mtu;		/* Max Tx packet size in bytes */
 	__u8  bulk_int_ep;		/* Interrupt Endpoint assignments */
 
-	wait_queue_head_t wait_q;	/* for timeouts */
-
 	struct urb *rx_urb[IU_MAX_RX_URBS];	/* URBs used to receive data frames */
 	struct urb *idle_rx_urb;	/* Pointer to idle URB in Rx path */
 	struct urb *tx_urb;		/* URB used to send data frames */
@@ -147,17 +145,18 @@ struct irda_usb_cb {
 	struct net_device_stats stats;
 	struct irlap_cb   *irlap;	/* The link layer we are binded to */
 	struct qos_info qos;
-	hashbin_t *tx_list;		/* Queued transmit skb's */
 	char *speed_buff;		/* Buffer for speed changes */
 
 	struct timeval stamp;
 	struct timeval now;
 
-	spinlock_t lock;		/* For serializing operations */
+	spinlock_t lock;		/* For serializing Tx operations */
 
 	__u16 xbofs;			/* Current xbofs setting */
 	__s16 new_xbofs;		/* xbofs we need to set */
 	__u32 speed;			/* Current speed */
 	__s32 new_speed;		/* speed we need to set */
+
+	struct timer_list rx_defer_timer;	/* Wait for Rx error to clear */
 };