Commit c78b7c58 authored by Bjørn Mork's avatar Bjørn Mork Committed by David S. Miller
Browse files

net: cdc_ncm: refactoring for tx multiplexing 



Adding multiplexed NDP support to cdc_ncm_fill_tx_frame, allowing
transmissions of multiple independent sessions within the same NTB.

Refactoring the code quite a bit to avoid having to store copies
of multiple NDPs being prepared for tx. The old code would still
reserve enough room for a maximum sized NDP in the skb so we might
as well keep them in the skb while they are being prepared.

Signed-off-by: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff06ab13

drivers/net/usb/cdc_ncm.c

+102 −145
Original line number Diff line number Diff line
@@ -88,14 +88,11 @@ 
	(sizeof(struct usb_cdc_ncm_nth16) + sizeof(struct usb_cdc_ncm_ndp16) + \

	(CDC_NCM_DPT_DATAGRAMS_MAX + 1) * sizeof(struct usb_cdc_ncm_dpe16))



struct cdc_ncm_data {

	struct usb_cdc_ncm_nth16 nth16;

	struct usb_cdc_ncm_ndp16 ndp16;

	struct usb_cdc_ncm_dpe16 dpe16[CDC_NCM_DPT_DATAGRAMS_MAX + 1];

};

#define CDC_NCM_NDP_SIZE \

	(sizeof(struct usb_cdc_ncm_ndp16) +				\

	      (CDC_NCM_DPT_DATAGRAMS_MAX + 1) * sizeof(struct usb_cdc_ncm_dpe16))



struct cdc_ncm_ctx {

	struct cdc_ncm_data tx_ncm;

	struct usb_cdc_ncm_ntb_parameters ncm_parm;

	struct hrtimer tx_timer;

	struct tasklet_struct bh;
@@ -117,13 +114,12 @@ struct cdc_ncm_ctx { 


	struct sk_buff *tx_curr_skb;

	struct sk_buff *tx_rem_skb;

	__le32 tx_rem_sign;



	spinlock_t mtx;

	atomic_t stop;



	u32 tx_timer_pending;

	u32 tx_curr_offset;

	u32 tx_curr_last_offset;

	u32 tx_curr_frame_num;

	u32 rx_speed;

	u32 tx_speed;
@@ -658,51 +654,75 @@ static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf) 
	return ret;

}



static void cdc_ncm_zero_fill(u8 *ptr, u32 first, u32 end, u32 max)

static void cdc_ncm_align_tail(struct sk_buff *skb, size_t modulus, size_t remainder, size_t max)

{

	if (first >= max)

		return;

	if (first >= end)

		return;

	if (end > max)

		end = max;

	memset(ptr + first, 0, end - first);

	size_t align = ALIGN(skb->len, modulus) - skb->len + remainder;



	if (skb->len + align > max)

		align = max - skb->len;

	if (align && skb_tailroom(skb) >= align)

		memset(skb_put(skb, align), 0, align);

}



/* return a pointer to a valid struct usb_cdc_ncm_ndp16 of type sign, possibly

 * allocating a new one within skb

 */

static struct usb_cdc_ncm_ndp16 *cdc_ncm_ndp(struct cdc_ncm_ctx *ctx, struct sk_buff *skb, __le32 sign, size_t reserve)

{

	struct usb_cdc_ncm_ndp16 *ndp16 = NULL;

	struct usb_cdc_ncm_nth16 *nth16 = (void *)skb->data;

	size_t ndpoffset = le16_to_cpu(nth16->wNdpIndex);



	/* follow the chain of NDPs, looking for a match */

	while (ndpoffset) {

		ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb->data + ndpoffset);

		if  (ndp16->dwSignature == sign)

			return ndp16;

		ndpoffset = le16_to_cpu(ndp16->wNextNdpIndex);

	}



	/* align new NDP */

	cdc_ncm_align_tail(skb, ctx->tx_ndp_modulus, 0, ctx->tx_max);



	/* verify that there is room for the NDP and the datagram (reserve) */

	if ((ctx->tx_max - skb->len - reserve) < CDC_NCM_NDP_SIZE)

		return NULL;



	/* link to it */

	if (ndp16)

		ndp16->wNextNdpIndex = cpu_to_le16(skb->len);

	else

		nth16->wNdpIndex = cpu_to_le16(skb->len);



	/* push a new empty NDP */

	ndp16 = (struct usb_cdc_ncm_ndp16 *)memset(skb_put(skb, CDC_NCM_NDP_SIZE), 0, CDC_NCM_NDP_SIZE);

	ndp16->dwSignature = sign;

	ndp16->wLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16) + sizeof(struct usb_cdc_ncm_dpe16));

	return ndp16;

}



static struct sk_buff *

cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb)

cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb, __le32 sign)

{

	struct usb_cdc_ncm_nth16 *nth16;

	struct usb_cdc_ncm_ndp16 *ndp16;

	struct sk_buff *skb_out;

	u32 rem;

	u32 offset;

	u32 last_offset;

	u16 n = 0, index;

	u16 n = 0, index, ndplen;

	u8 ready2send = 0;



	/* if there is a remaining skb, it gets priority */

	if (skb != NULL)

	if (skb != NULL) {

		swap(skb, ctx->tx_rem_skb);

	else

		swap(sign, ctx->tx_rem_sign);

	} else {

		ready2send = 1;



	/*

	 * +----------------+

	 * | skb_out        |

	 * +----------------+

	 *           ^ offset

	 *        ^ last_offset

	 */

	}



	/* check if we are resuming an OUT skb */

	if (ctx->tx_curr_skb != NULL) {

		/* pop variables */

	skb_out = ctx->tx_curr_skb;

		offset = ctx->tx_curr_offset;

		last_offset = ctx->tx_curr_last_offset;

		n = ctx->tx_curr_frame_num;



	} else {

		/* reset variables */

	/* allocate a new OUT skb */

	if (!skb_out) {

		skb_out = alloc_skb((ctx->tx_max + 1), GFP_ATOMIC);

		if (skb_out == NULL) {

			if (skb != NULL) {
@@ -711,35 +731,21 @@ cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb) 
			}

			goto exit_no_skb;

		}

		/* fill out the initial 16-bit NTB header */

		nth16 = (struct usb_cdc_ncm_nth16 *)memset(skb_put(skb_out, sizeof(struct usb_cdc_ncm_nth16)), 0, sizeof(struct usb_cdc_ncm_nth16));

		nth16->dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);

		nth16->wHeaderLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16));

		nth16->wSequence = cpu_to_le16(ctx->tx_seq++);



		/* make room for NTH and NDP */

		offset = ALIGN(sizeof(struct usb_cdc_ncm_nth16),

					ctx->tx_ndp_modulus) +

					sizeof(struct usb_cdc_ncm_ndp16) +

					(ctx->tx_max_datagrams + 1) *

					sizeof(struct usb_cdc_ncm_dpe16);



		/* store last valid offset before alignment */

		last_offset = offset;

		/* align first Datagram offset correctly */

		offset = ALIGN(offset, ctx->tx_modulus) + ctx->tx_remainder;

		/* zero buffer till the first IP datagram */

		cdc_ncm_zero_fill(skb_out->data, 0, offset, offset);

		n = 0;

		/* count total number of frames in this NTB */

		ctx->tx_curr_frame_num = 0;

	}



	for (; n < ctx->tx_max_datagrams; n++) {

		/* check if end of transmit buffer is reached */

		if (offset >= ctx->tx_max) {

			ready2send = 1;

			break;

		}

		/* compute maximum buffer size */

		rem = ctx->tx_max - offset;



	for (n = ctx->tx_curr_frame_num; n < ctx->tx_max_datagrams; n++) {

		/* send any remaining skb first */

		if (skb == NULL) {

			skb = ctx->tx_rem_skb;

			sign = ctx->tx_rem_sign;

			ctx->tx_rem_skb = NULL;



			/* check for end of skb */
@@ -747,7 +753,14 @@ cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb) 
				break;

		}



		if (skb->len > rem) {

		/* get the appropriate NDP for this skb */

		ndp16 = cdc_ncm_ndp(ctx, skb_out, sign, skb->len + ctx->tx_modulus + ctx->tx_remainder);



		/* align beginning of next frame */

		cdc_ncm_align_tail(skb_out,  ctx->tx_modulus, ctx->tx_remainder, ctx->tx_max);



		/* check if we had enough room left for both NDP and frame */

		if (!ndp16 || skb_out->len + skb->len > ctx->tx_max) {

			if (n == 0) {

				/* won't fit, MTU problem? */

				dev_kfree_skb_any(skb);
@@ -760,31 +773,30 @@ cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb) 
					ctx->netdev->stats.tx_dropped++;

				}

				ctx->tx_rem_skb = skb;

				ctx->tx_rem_sign = sign;

				skb = NULL;

				ready2send = 1;

			}

			break;

		}



		memcpy(((u8 *)skb_out->data) + offset, skb->data, skb->len);



		ctx->tx_ncm.dpe16[n].wDatagramLength = cpu_to_le16(skb->len);

		ctx->tx_ncm.dpe16[n].wDatagramIndex = cpu_to_le16(offset);



		/* update offset */

		offset += skb->len;

		/* calculate frame number withing this NDP */

		ndplen = le16_to_cpu(ndp16->wLength);

		index = (ndplen - sizeof(struct usb_cdc_ncm_ndp16)) / sizeof(struct usb_cdc_ncm_dpe16) - 1;



		/* store last valid offset before alignment */

		last_offset = offset;



		/* align offset correctly */

		offset = ALIGN(offset, ctx->tx_modulus) + ctx->tx_remainder;



		/* zero padding */

		cdc_ncm_zero_fill(skb_out->data, last_offset, offset,

								ctx->tx_max);

		/* OK, add this skb */

		ndp16->dpe16[index].wDatagramLength = cpu_to_le16(skb->len);

		ndp16->dpe16[index].wDatagramIndex = cpu_to_le16(skb_out->len);

		ndp16->wLength = cpu_to_le16(ndplen + sizeof(struct usb_cdc_ncm_dpe16));

		memcpy(skb_put(skb_out, skb->len), skb->data, skb->len);

		dev_kfree_skb_any(skb);

		skb = NULL;



		/* send now if this NDP is full */

		if (index >= CDC_NCM_DPT_DATAGRAMS_MAX) {

			ready2send = 1;

			break;

		}

	}



	/* free up any dangling skb */
@@ -800,16 +812,12 @@ cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb) 
		/* wait for more frames */

		/* push variables */

		ctx->tx_curr_skb = skb_out;

		ctx->tx_curr_offset = offset;

		ctx->tx_curr_last_offset = last_offset;

		goto exit_no_skb;



	} else if ((n < ctx->tx_max_datagrams) && (ready2send == 0)) {

		/* wait for more frames */

		/* push variables */

		ctx->tx_curr_skb = skb_out;

		ctx->tx_curr_offset = offset;

		ctx->tx_curr_last_offset = last_offset;

		/* set the pending count */

		if (n < CDC_NCM_RESTART_TIMER_DATAGRAM_CNT)

			ctx->tx_timer_pending = CDC_NCM_TIMER_PENDING_CNT;
@@ -820,75 +828,24 @@ cdc_ncm_fill_tx_frame(struct cdc_ncm_ctx *ctx, struct sk_buff *skb) 
		/* variables will be reset at next call */

	}



	/* check for overflow */

	if (last_offset > ctx->tx_max)

		last_offset = ctx->tx_max;



	/* revert offset */

	offset = last_offset;



	/*

	 * If collected data size is less or equal CDC_NCM_MIN_TX_PKT bytes,

	 * we send buffers as it is. If we get more data, it would be more

	 * efficient for USB HS mobile device with DMA engine to receive a full

	 * size NTB, than canceling DMA transfer and receiving a short packet.

	 */

	if (offset > CDC_NCM_MIN_TX_PKT)

		offset = ctx->tx_max;



	if (skb_out->len > CDC_NCM_MIN_TX_PKT)

		/* final zero padding */

	cdc_ncm_zero_fill(skb_out->data, last_offset, offset, ctx->tx_max);



	/* store last offset */

	last_offset = offset;



	if (((last_offset < ctx->tx_max) && ((last_offset %

			le16_to_cpu(ctx->out_ep->desc.wMaxPacketSize)) == 0)) ||

	    (((last_offset == ctx->tx_max) && ((ctx->tx_max %

		le16_to_cpu(ctx->out_ep->desc.wMaxPacketSize)) == 0)) &&

		(ctx->tx_max < le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize)))) {

		/* force short packet */

		*(((u8 *)skb_out->data) + last_offset) = 0;

		last_offset++;

	}



	/* zero the rest of the DPEs plus the last NULL entry */

	for (; n <= CDC_NCM_DPT_DATAGRAMS_MAX; n++) {

		ctx->tx_ncm.dpe16[n].wDatagramLength = 0;

		ctx->tx_ncm.dpe16[n].wDatagramIndex = 0;

	}



	/* fill out 16-bit NTB header */

	ctx->tx_ncm.nth16.dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);

	ctx->tx_ncm.nth16.wHeaderLength =

					cpu_to_le16(sizeof(ctx->tx_ncm.nth16));

	ctx->tx_ncm.nth16.wSequence = cpu_to_le16(ctx->tx_seq);

	ctx->tx_ncm.nth16.wBlockLength = cpu_to_le16(last_offset);

	index = ALIGN(sizeof(struct usb_cdc_ncm_nth16), ctx->tx_ndp_modulus);

	ctx->tx_ncm.nth16.wNdpIndex = cpu_to_le16(index);



	memcpy(skb_out->data, &(ctx->tx_ncm.nth16), sizeof(ctx->tx_ncm.nth16));

	ctx->tx_seq++;



	/* fill out 16-bit NDP table */

	ctx->tx_ncm.ndp16.dwSignature =

				cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN);

	rem = sizeof(ctx->tx_ncm.ndp16) + ((ctx->tx_curr_frame_num + 1) *

					sizeof(struct usb_cdc_ncm_dpe16));

	ctx->tx_ncm.ndp16.wLength = cpu_to_le16(rem);

	ctx->tx_ncm.ndp16.wNextNdpIndex = 0; /* reserved */



	memcpy(((u8 *)skb_out->data) + index,

						&(ctx->tx_ncm.ndp16),

						sizeof(ctx->tx_ncm.ndp16));

		memset(skb_put(skb_out, ctx->tx_max - skb_out->len), 0, ctx->tx_max - skb_out->len);



	memcpy(((u8 *)skb_out->data) + index + sizeof(ctx->tx_ncm.ndp16),

					&(ctx->tx_ncm.dpe16),

					(ctx->tx_curr_frame_num + 1) *

					sizeof(struct usb_cdc_ncm_dpe16));

	/* do we need to prevent a ZLP? */

	if (((skb_out->len % le16_to_cpu(ctx->out_ep->desc.wMaxPacketSize)) == 0) &&

	    (skb_out->len < le32_to_cpu(ctx->ncm_parm.dwNtbOutMaxSize)) && skb_tailroom(skb_out))

		*skb_put(skb_out, 1) = 0;	/* force short packet */



	/* set frame length */

	skb_put(skb_out, last_offset);

	/* set final frame length */

	nth16 = (struct usb_cdc_ncm_nth16 *)skb_out->data;

	nth16->wBlockLength = cpu_to_le16(skb_out->len);



	/* return skb */

	ctx->tx_curr_skb = NULL;
@@ -955,7 +912,7 @@ cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags) 
		goto error;



	spin_lock_bh(&ctx->mtx);

	skb_out = cdc_ncm_fill_tx_frame(ctx, skb);

	skb_out = cdc_ncm_fill_tx_frame(ctx, skb, cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN));

	spin_unlock_bh(&ctx->mtx);

	return skb_out;

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