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Commit 3958fb34 authored by Samuel Ortiz's avatar Samuel Ortiz Committed by David S. Miller
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[IrDA]: irda-usb TX path optimization (was Re: IrDA spams logfiles - since 2.6.19) 



Since we stop using dev_alloc_skb on the IrDA TX frame, we constantly run
into the case of the skb headroom being 0, and thus we call skb_cow for
every IrDA TX frame.
This patch uses a local buffer and memcpy the skb to it, saving us a
kmalloc for each of those IrDA TX frames.

Signed-off-by: default avatarSamuel Ortiz <samuel@sortiz.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9d0f7d29

drivers/net/irda/irda-usb.c

+20 −23
Original line number Diff line number Diff line
@@ -441,25 +441,13 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev) 
		goto drop;

	}



	/* 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) < self->header_length) {

		IRDA_DEBUG(0, "%s(), Insuficient skb headroom.\n", __FUNCTION__);

		if (skb_cow(skb, self->header_length)) {

			IRDA_WARNING("%s(), failed skb_cow() !!!\n", __FUNCTION__);

			goto drop;

		}

	}

	memcpy(self->tx_buff + self->header_length, skb->data, skb->len);



	/* Change setting for next frame */



	if (self->capability & IUC_STIR421X) {

		__u8 turnaround_time;

		__u8* frame;

		__u8* frame = self->tx_buff;

		turnaround_time = get_turnaround_time( skb );

		frame= skb_push(skb, self->header_length);

		irda_usb_build_header(self, frame, 0);

		frame[2] = turnaround_time;

		if ((skb->len != 0) &&
@@ -472,7 +460,7 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev) 
			frame[1] = 0;

		}

	} else {

		irda_usb_build_header(self, skb_push(skb, self->header_length), 0);

		irda_usb_build_header(self, self->tx_buff, 0);

	}



	/* FIXME: Make macro out of this one */
@@ -480,9 +468,9 @@ static int irda_usb_hard_xmit(struct sk_buff *skb, struct net_device *netdev) 


	usb_fill_bulk_urb(urb, self->usbdev,

		      usb_sndbulkpipe(self->usbdev, self->bulk_out_ep),

                      skb->data, IRDA_SKB_MAX_MTU,

                      self->tx_buff, skb->len + self->header_length,

                      write_bulk_callback, skb);

	urb->transfer_buffer_length = skb->len;



	/* This flag (URB_ZERO_PACKET) indicates that what we send is not

	 * a continuous stream of data but separate packets.

	 * In this case, the USB layer will insert an empty USB frame (TD)
@@ -1455,6 +1443,9 @@ static inline void irda_usb_close(struct irda_usb_cb *self) 
	/* Remove the speed buffer */

	kfree(self->speed_buff);

	self->speed_buff = NULL;



	kfree(self->tx_buff);

	self->tx_buff = NULL;

}



/********************** USB CONFIG SUBROUTINES **********************/
@@ -1753,9 +1744,14 @@ static int irda_usb_probe(struct usb_interface *intf, 


	memset(self->speed_buff, 0, IRDA_USB_SPEED_MTU);



	self->tx_buff = kzalloc(IRDA_SKB_MAX_MTU + self->header_length,

				GFP_KERNEL);

	if (self->tx_buff == NULL)

		goto err_out_4;



	ret = irda_usb_open(self);

	if (ret) 

		goto err_out_4;

		goto err_out_5;



	IRDA_MESSAGE("IrDA: Registered device %s\n", net->name);

	usb_set_intfdata(intf, self);
@@ -1766,14 +1762,14 @@ static int irda_usb_probe(struct usb_interface *intf, 
		self->needspatch = (ret < 0);

		if (self->needspatch) {

			IRDA_ERROR("STIR421X: Couldn't upload patch\n");

			goto err_out_5;

			goto err_out_6;

		}



		/* replace IrDA class descriptor with what patched device is now reporting */

		irda_desc = irda_usb_find_class_desc (self->usbintf);

		if (irda_desc == NULL) {

			ret = -ENODEV;

			goto err_out_5;

			goto err_out_6;

		}

		if (self->irda_desc)

			kfree (self->irda_desc);
@@ -1782,9 +1778,10 @@ static int irda_usb_probe(struct usb_interface *intf, 
	}



	return 0;



err_out_5:

err_out_6:

	unregister_netdev(self->netdev);

err_out_5:

	kfree(self->tx_buff);

err_out_4:

	kfree(self->speed_buff);

err_out_3:

drivers/net/irda/irda-usb.h

+1 −0
Original line number Diff line number Diff line
@@ -156,6 +156,7 @@ struct irda_usb_cb { 
	struct irlap_cb   *irlap;	/* The link layer we are binded to */

	struct qos_info qos;

	char *speed_buff;		/* Buffer for speed changes */

	char *tx_buff;



	struct timeval stamp;

	struct timeval now;