From: Jean Tourrilhes <jt@bougret.hpl.hp.com>
To: Marcelo Tosatti <marcelo@conectiva.com.br>,
Linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: [PATCH] : ir249_usb_cow-2.diff
Date: Tue, 5 Mar 2002 17:54:06 -0800 [thread overview]
Message-ID: <20020305175406.H1577@bougret.hpl.hp.com> (raw)
ir249_usb_cow-2.diff :
--------------------
o [FEATURE] Don't use skb_cow() unless we really need to
o [CORRECT] Reorder URB init to avoid races
o [CORRECT] USB delay adds processing time, not removes it
diff -u -p linux/drivers/net/irda/irda-usb.d4.c linux/drivers/net/irda/irda-usb.c
--- linux/drivers/net/irda/irda-usb.d4.c Tue Mar 5 16:04:01 2002
+++ linux/drivers/net/irda/irda-usb.c Tue Mar 5 16:46:27 2002
@@ -378,10 +378,17 @@ static int irda_usb_hard_xmit(struct sk_
return 0;
}
- /* Make room for IrDA-USB header (note skb->len += USB_IRDA_HEADER) */
- if (skb_cow(skb, USB_IRDA_HEADER)) {
- dev_kfree_skb(skb);
- return 0;
+ /* 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_
#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;
@@ -848,8 +855,8 @@ done:
/* 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 = purb;
purb->context = NULL;
+ self->idle_rx_urb = purb;
}
/*------------------------------------------------------------------*/
@@ -952,13 +959,17 @@ static int irda_usb_net_open(struct net_
/* 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;
/* Ready to play !!! */
MOD_INC_USE_COUNT;
reply other threads:[~2002-03-06 1:55 UTC|newest]
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