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Commit b91cd144 authored by Rémi Denis-Courmont's avatar Rémi Denis-Courmont Committed by David S. Miller
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f_phonet: use page-sized rather than MTU-sized RX buffers 



Instead of a large (physically) linear buffer, we generate a set of
paged sk_buff, so no extra memory copy is involved. This removes
high-order allocations and saves quite a bit of memory. Phonet MTU is
65541 bytes, so the two buffers were padded to 128 kilo-bytes each.
Now, we create 17 page buffers, almost a 75% memory use reduction.

Signed-off-by: default avatarRémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5da63cc4

drivers/usb/gadget/f_phonet.c

+51 −26
Original line number Diff line number Diff line
@@ -35,6 +35,10 @@ 
#include "u_phonet.h"



#define PN_MEDIA_USB	0x1B

#define MAXPACKET	512

#if (PAGE_SIZE % MAXPACKET)

#error MAXPACKET must divide PAGE_SIZE!

#endif



/*-------------------------------------------------------------------------*/
@@ -45,6 +49,10 @@ struct phonet_port { 


struct f_phonet {

	struct usb_function		function;

	struct {

		struct sk_buff		*skb;

		spinlock_t		lock;

	} rx;

	struct net_device		*dev;

	struct usb_ep			*in_ep, *out_ep;
@@ -52,7 +60,7 @@ struct f_phonet { 
	struct usb_request		*out_reqv[0];

};



static int phonet_rxq_size = 2;

static int phonet_rxq_size = 17;



static inline struct f_phonet *func_to_pn(struct usb_function *f)

{
@@ -138,7 +146,7 @@ pn_hs_sink_desc = { 


	.bEndpointAddress =	USB_DIR_OUT,

	.bmAttributes =		USB_ENDPOINT_XFER_BULK,

	.wMaxPacketSize =	cpu_to_le16(512),

	.wMaxPacketSize =	cpu_to_le16(MAXPACKET),

};



static struct usb_endpoint_descriptor
@@ -298,21 +306,21 @@ static void pn_net_setup(struct net_device *dev) 
static int

pn_rx_submit(struct f_phonet *fp, struct usb_request *req, gfp_t gfp_flags)

{

	struct sk_buff *skb;

	const size_t size = fp->dev->mtu;

	struct net_device *dev = fp->dev;

	struct page *page;

	int err;



	skb = alloc_skb(size, gfp_flags);

	if (!skb)

	page = __netdev_alloc_page(dev, gfp_flags);

	if (!page)

		return -ENOMEM;



	req->buf = skb->data;

	req->length = size;

	req->context = skb;

	req->buf = page_address(page);

	req->length = PAGE_SIZE;

	req->context = page;



	err = usb_ep_queue(fp->out_ep, req, gfp_flags);

	if (unlikely(err))

		dev_kfree_skb_any(skb);

		netdev_free_page(dev, page);

	return err;

}
@@ -320,25 +328,37 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req) 
{

	struct f_phonet *fp = ep->driver_data;

	struct net_device *dev = fp->dev;

	struct sk_buff *skb = req->context;

	struct page *page = req->context;

	struct sk_buff *skb;

	unsigned long flags;

	int status = req->status;



	switch (status) {

	case 0:

		if (unlikely(!netif_running(dev)))

			break;

		if (unlikely(req->actual < 1))

		spin_lock_irqsave(&fp->rx.lock, flags);

		skb = fp->rx.skb;

		if (!skb)

			skb = fp->rx.skb = netdev_alloc_skb(dev, 12);

		if (req->actual < req->length) /* Last fragment */

			fp->rx.skb = NULL;

		spin_unlock_irqrestore(&fp->rx.lock, flags);



		if (unlikely(!skb))

			break;

		skb_put(skb, req->actual);

		skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, 0,

				req->actual);

		page = NULL;



		if (req->actual < req->length) { /* Last fragment */

			skb->protocol = htons(ETH_P_PHONET);

			skb_reset_mac_header(skb);

		__skb_pull(skb, 1);

			pskb_pull(skb, 1);

			skb->dev = dev;

			dev->stats.rx_packets++;

			dev->stats.rx_bytes += skb->len;



			netif_rx(skb);

		skb = NULL;

		}

		break;



	/* Do not resubmit in these cases: */
@@ -356,8 +376,8 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req) 
		break;

	}



	if (skb)

		dev_kfree_skb_any(skb);

	if (page)

		netdev_free_page(dev, page);

	if (req)

		pn_rx_submit(fp, req, GFP_ATOMIC);

}
@@ -375,6 +395,10 @@ static void __pn_reset(struct usb_function *f) 


	usb_ep_disable(fp->out_ep);

	usb_ep_disable(fp->in_ep);

	if (fp->rx.skb) {

		dev_kfree_skb_irq(fp->rx.skb);

		fp->rx.skb = NULL;

	}

}



static int pn_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
@@ -573,6 +597,7 @@ int __init phonet_bind_config(struct usb_configuration *c) 
	fp->function.set_alt = pn_set_alt;

	fp->function.get_alt = pn_get_alt;

	fp->function.disable = pn_disconnect;

	spin_lock_init(&fp->rx.lock);



	err = usb_add_function(c, &fp->function);

	if (err)