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: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 6688a15..2dd2734 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -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 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 @@
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;
+ skb_out = ctx->tx_curr_skb;
- } 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 @@
}
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 @@
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 @@
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);
+ /* 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;
- 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;
-
- /* 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 @@
/* 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 @@
/* 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 */
+ memset(skb_put(skb_out, ctx->tx_max - skb_out->len), 0, ctx->tx_max - skb_out->len);
- /* final zero padding */
- cdc_ncm_zero_fill(skb_out->data, last_offset, offset, ctx->tx_max);
+ /* 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 */
- /* 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));
-
- 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));
-
- /* 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 @@
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;
