[PATCH] : ir256_usb_cow_urballoc.diff

ir256_usb_cow_urballoc.diff :
 ---------------------------
	o [FEATURE] Don't use skb_cow() unless we really need to
	o [CORRECT] Reorder URB init to avoid races
	o [CORRECT] USB dealy adds processing time, not removes it
        <Following patch from Greg KH <greg@kroah.com> himself !!!>
	o [CRITICA] Use dynamically allocated URBs (instead of statically)

drivers/net/irda/irda-usb.c

@@ -255,7 +255,7 @@ static void irda_usb_change_speed_xbofs(struct irda_usb_cb *self)
 		   self->new_speed, self->new_xbofs);
 
 	/* Grab the speed URB */
-	urb = &self->speed_urb;
+	urb = self->speed_urb;
 	if (urb->status != 0) {
 		WARNING(__FUNCTION__ "(), URB still in use!\n");
 		return;
@@ -317,7 +317,7 @@ static void speed_bulk_callback(struct urb *urb)
 	urb->status = 0;
 
 	/* If it was the speed URB, allow the stack to send more packets */
-	if(urb == &self->speed_urb) {
+	if(urb == self->speed_urb) {
 		netif_wake_queue(self->netdev);
 	}
 }
@@ -329,7 +329,7 @@ static void speed_bulk_callback(struct urb *urb)
 static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
 	struct irda_usb_cb *self = netdev->priv;
-	struct urb *urb = &self->tx_urb;
+	struct urb *urb = self->tx_urb;
 	unsigned long flags;
 	s32 speed;
 	s16 xbofs;
@@ -378,11 +378,18 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev)
 		return 0;
 	}
 
-	/* Make room for IrDA-USB header (note skb->len += USB_IRDA_HEADER) */
+	/* Make sure there is room for IrDA-USB header. The actual
+	 * allocation will be done lower in skb_push().
+	 * Also, we don't use directly skb_cow(), because it require
+	 * headroom >= 16, which force unnecessary copies - Jean II */
+	if (skb_headroom(skb) < USB_IRDA_HEADER) {
+		IRDA_DEBUG(0, __FUNCTION__ "(), Insuficient skb headroom.\n");
 		if (skb_cow(skb, USB_IRDA_HEADER)) {
+			WARNING(__FUNCTION__ "(), failed skb_cow() !!!\n");
 			dev_kfree_skb(skb);
 			return 0;
 		}
+	}
 
 	spin_lock_irqsave(&self->lock, flags);
 
@@ -432,7 +439,7 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev)
 #ifdef IU_USB_MIN_RTT
 			/* Factor in USB delays -> Get rid of udelay() that
 			 * would be lost in the noise - Jean II */
-			diff -= IU_USB_MIN_RTT;
+			diff += IU_USB_MIN_RTT;
 #endif /* IU_USB_MIN_RTT */
 			if (diff < 0)
 				diff += 1000000;
@@ -546,7 +553,7 @@ static void irda_usb_net_timeout(struct net_device *netdev)
 	}
 
 	/* Check speed URB */
-	urb = &(self->speed_urb);
+	urb = self->speed_urb;
 	if (urb->status != 0) {
 		IRDA_DEBUG(0, "%s: Speed change timed out, urb->status=%d, urb->transfer_flags=0x%04X\n", netdev->name, urb->status, urb->transfer_flags);
 
@@ -571,7 +578,7 @@ static void irda_usb_net_timeout(struct net_device *netdev)
 	}
 
 	/* Check Tx URB */
-	urb = &(self->tx_urb);
+	urb = self->tx_urb;
 	if (urb->status != 0) {
 		struct sk_buff *skb = urb->context;
 
@@ -848,8 +855,8 @@ static void irda_usb_receive(struct urb *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 */
-	self->idle_rx_urb = urb;
 	urb->context = NULL;
+	self->idle_rx_urb = urb;
 }
 
 /*------------------------------------------------------------------*/
@@ -952,13 +959,17 @@ static int irda_usb_net_open(struct net_device *netdev)
 	/* Allow IrLAP to send data to us */
 	netif_start_queue(netdev);
 
+	/* We submit all the Rx URB except for one that we keep idle.
+	 * Need to be initialised before submitting other USBs, because
+	 * in some cases as soon as we submit the URBs the USB layer
+	 * will trigger a dummy receive - Jean II */
+	self->idle_rx_urb = self->rx_urb[IU_MAX_ACTIVE_RX_URBS];
+	self->idle_rx_urb->context = NULL;
+
 	/* Now that we can pass data to IrLAP, allow the USB layer
 	 * to send us some data... */
 	for (i = 0; i < IU_MAX_ACTIVE_RX_URBS; i++)
-		irda_usb_submit(self, NULL, &(self->rx_urb[i]));
-	/* Note : we submit all the Rx URB except for one - Jean II */
-	self->idle_rx_urb = &(self->rx_urb[IU_MAX_ACTIVE_RX_URBS]);
-	self->idle_rx_urb->context = NULL;
+		irda_usb_submit(self, NULL, self->rx_urb[i]);
 
 	/* Ready to play !!! */
 	MOD_INC_USE_COUNT;
@@ -992,7 +1003,7 @@ static int irda_usb_net_close(struct net_device *netdev)
 
 	/* 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]);
+		struct urb *urb = self->rx_urb[i];
 		struct sk_buff *skb = (struct sk_buff *) urb->context;
 		/* Cancel the receive command */
 		usb_unlink_urb(urb);
@@ -1003,8 +1014,8 @@ static int irda_usb_net_close(struct net_device *netdev)
 		}
 	}
 	/* Cancel Tx and speed URB */
-	usb_unlink_urb(&(self->tx_urb));
-	usb_unlink_urb(&(self->speed_urb));
+	usb_unlink_urb(self->tx_urb);
+	usb_unlink_urb(self->speed_urb);
 
 	/* Stop and remove instance of IrLAP */
 	if (self->irlap)
@@ -1429,6 +1440,30 @@ static void *irda_usb_probe(struct usb_device *dev, unsigned int ifnum,
 	self->present = 0;
 	self->netopen = 0;
 
+	/* Create all of the needed urbs */
+	for (i = 0; i < IU_MAX_RX_URBS; i++) {
+		self->rx_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
+		if (!self->rx_urb[i]) {
+			int j;
+			for (j = 0; j < i; j++)
+				usb_free_urb(self->rx_urb[j]);
+			return NULL;
+		}
+	}
+	self->tx_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!self->tx_urb) {
+		for (i = 0; i < IU_MAX_RX_URBS; i++)
+			usb_free_urb(self->rx_urb[i]);
+		return NULL;
+	}
+	self->speed_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!self->speed_urb) {
+		for (i = 0; i < IU_MAX_RX_URBS; i++)
+			usb_free_urb(self->rx_urb[i]);
+		usb_free_urb(self->tx_urb);
+		return NULL;
+	}
+
 	/* Is this really necessary? */
 	if (usb_set_configuration (dev, dev->config[0].bConfigurationValue) < 0) {
 		err("set_configuration failed");
@@ -1501,10 +1536,10 @@ static void irda_usb_disconnect(struct usb_device *dev, void *ptr)
 		netif_stop_queue(self->netdev);
 		/* Stop all the receive URBs */
 		for (i = 0; i < IU_MAX_RX_URBS; i++)
-			usb_unlink_urb(&(self->rx_urb[i]));
+			usb_unlink_urb(self->rx_urb[i]);
 		/* Cancel Tx and speed URB */
-		usb_unlink_urb(&(self->tx_urb));
-		usb_unlink_urb(&(self->speed_urb));
+		usb_unlink_urb(self->tx_urb);
+		usb_unlink_urb(self->speed_urb);
 
 		IRDA_DEBUG(0, __FUNCTION__ "(), postponing disconnect, network is still active...\n");
 		/* better not do anything just yet, usb_irda_cleanup()
@@ -1516,6 +1551,14 @@ static void irda_usb_disconnect(struct usb_device *dev, void *ptr)
 	irda_usb_close(self);
 	/* No longer attached to USB bus */
 	self->usbdev = NULL;
+
+	/* Clean up our urbs */
+	for (i = 0; i < IU_MAX_RX_URBS; i++)
+		usb_free_urb(self->rx_urb[i]);
+	/* Cancel Tx and speed URB */
+	usb_free_urb(self->tx_urb);
+	usb_free_urb(self->speed_urb);
+
 	IRDA_DEBUG(0, __FUNCTION__ "(), USB IrDA Disconnected\n");
 }
 

include/net/irda/irda-usb.h

@@ -139,10 +139,10 @@ struct irda_usb_cb {
 
 	wait_queue_head_t wait_q;	/* for timeouts */
 
-	struct urb rx_urb[IU_MAX_RX_URBS];	/* URBs used to receive data frames */
+	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 */
-	struct urb speed_urb;		/* URB used to send speed commands */
+	struct urb *tx_urb;		/* URB used to send data frames */
+	struct urb *speed_urb;		/* URB used to send speed commands */
 	
 	struct net_device *netdev;	/* Yes! we are some kind of netdev. */
 	struct net_device_stats stats;