[PATCH 11/13] USBATM: handle urbs containing partial cells

From: Duncan Sands
Date: Fri Jan 13 2006 - 05:06:21 EST


The receive logic has always assumed that urbs contain an integral
number of ATM cells, which is a bit naughty, though it never caused
any problems with bulk transfers. Isochronous urbs spank us soundly
for this. Fixed thanks to this patch, mostly by Stanislaw Gruszka.

Signed-off-by: Duncan Sands <baldrick@xxxxxxx>
Index: Linux/drivers/usb/atm/usbatm.c
===================================================================
--- Linux.orig/drivers/usb/atm/usbatm.c 2006-01-13 09:12:53.000000000 +0100
+++ Linux/drivers/usb/atm/usbatm.c 2006-01-13 09:25:43.000000000 +0100
@@ -296,126 +296,159 @@
return NULL;
}

-static void usbatm_extract_cells(struct usbatm_data *instance,
- unsigned char *source, unsigned int avail_data)
+static void usbatm_extract_one_cell(struct usbatm_data *instance, unsigned char *source)
{
- struct usbatm_vcc_data *cached_vcc = NULL;
struct atm_vcc *vcc;
struct sk_buff *sarb;
- unsigned int stride = instance->rx_channel.stride;
- int vci, cached_vci = 0;
- short vpi, cached_vpi = 0;
- u8 pti;
+ short vpi = ((source[0] & 0x0f) << 4) | (source[1] >> 4);
+ int vci = ((source[1] & 0x0f) << 12) | (source[2] << 4) | (source[3] >> 4);
+ u8 pti = ((source[3] & 0xe) >> 1);

- for (; avail_data >= stride; avail_data -= stride, source += stride) {
- vpi = ((source[0] & 0x0f) << 4) | (source[1] >> 4);
- vci = ((source[1] & 0x0f) << 12) | (source[2] << 4) | (source[3] >> 4);
- pti = ((source[3] & 0xe) >> 1);
+ vdbg("%s: vpi %hd, vci %d, pti %d", __func__, vpi, vci, pti);

- vdbg("%s: vpi %hd, vci %d, pti %d", __func__, vpi, vci, pti);
+ if ((vci != instance->cached_vci) || (vpi != instance->cached_vpi)) {
+ instance->cached_vpi = vpi;
+ instance->cached_vci = vci;

- if ((vci != cached_vci) || (vpi != cached_vpi)) {
- cached_vpi = vpi;
- cached_vci = vci;
+ instance->cached_vcc = usbatm_find_vcc(instance, vpi, vci);

- cached_vcc = usbatm_find_vcc(instance, vpi, vci);
+ if (!instance->cached_vcc)
+ atm_rldbg(instance, "%s: unknown vpi/vci (%hd/%d)!\n", __func__, vpi, vci);
+ }

- if (!cached_vcc)
- atm_rldbg(instance, "%s: unknown vpi/vci (%hd/%d)!\n", __func__, vpi, vci);
- }
+ if (!instance->cached_vcc)
+ return;

- if (!cached_vcc)
- continue;
+ vcc = instance->cached_vcc->vcc;

- vcc = cached_vcc->vcc;
+ /* OAM F5 end-to-end */
+ if (pti == ATM_PTI_E2EF5) {
+ if (printk_ratelimit())
+ atm_warn(instance, "%s: OAM not supported (vpi %d, vci %d)!\n",
+ __func__, vpi, vci);
+ atomic_inc(&vcc->stats->rx_err);
+ return;
+ }

- /* OAM F5 end-to-end */
- if (pti == ATM_PTI_E2EF5) {
- if (printk_ratelimit())
- atm_warn(instance, "%s: OAM not supported (vpi %d, vci %d)!\n",
- __func__, vpi, vci);
+ sarb = instance->cached_vcc->sarb;
+
+ if (sarb->tail + ATM_CELL_PAYLOAD > sarb->end) {
+ atm_rldbg(instance, "%s: buffer overrun (sarb->len %u, vcc: 0x%p)!\n",
+ __func__, sarb->len, vcc);
+ /* discard cells already received */
+ skb_trim(sarb, 0);
+ UDSL_ASSERT(sarb->tail + ATM_CELL_PAYLOAD <= sarb->end);
+ }
+
+ memcpy(sarb->tail, source + ATM_CELL_HEADER, ATM_CELL_PAYLOAD);
+ __skb_put(sarb, ATM_CELL_PAYLOAD);
+
+ if (pti & 1) {
+ struct sk_buff *skb;
+ unsigned int length;
+ unsigned int pdu_length;
+
+ length = (source[ATM_CELL_SIZE - 6] << 8) + source[ATM_CELL_SIZE - 5];
+
+ /* guard against overflow */
+ if (length > ATM_MAX_AAL5_PDU) {
+ atm_rldbg(instance, "%s: bogus length %u (vcc: 0x%p)!\n",
+ __func__, length, vcc);
atomic_inc(&vcc->stats->rx_err);
- continue;
+ goto out;
}

- sarb = cached_vcc->sarb;
+ pdu_length = usbatm_pdu_length(length);

- if (sarb->tail + ATM_CELL_PAYLOAD > sarb->end) {
- atm_rldbg(instance, "%s: buffer overrun (sarb->len %u, vcc: 0x%p)!\n",
- __func__, sarb->len, vcc);
- /* discard cells already received */
- skb_trim(sarb, 0);
- UDSL_ASSERT(sarb->tail + ATM_CELL_PAYLOAD <= sarb->end);
- }
-
- memcpy(sarb->tail, source + ATM_CELL_HEADER, ATM_CELL_PAYLOAD);
- __skb_put(sarb, ATM_CELL_PAYLOAD);
-
- if (pti & 1) {
- struct sk_buff *skb;
- unsigned int length;
- unsigned int pdu_length;
-
- length = (source[ATM_CELL_SIZE - 6] << 8) + source[ATM_CELL_SIZE - 5];
-
- /* guard against overflow */
- if (length > ATM_MAX_AAL5_PDU) {
- atm_rldbg(instance, "%s: bogus length %u (vcc: 0x%p)!\n",
- __func__, length, vcc);
- atomic_inc(&vcc->stats->rx_err);
- goto out;
- }
+ if (sarb->len < pdu_length) {
+ atm_rldbg(instance, "%s: bogus pdu_length %u (sarb->len: %u, vcc: 0x%p)!\n",
+ __func__, pdu_length, sarb->len, vcc);
+ atomic_inc(&vcc->stats->rx_err);
+ goto out;
+ }

- pdu_length = usbatm_pdu_length(length);
+ if (crc32_be(~0, sarb->tail - pdu_length, pdu_length) != 0xc704dd7b) {
+ atm_rldbg(instance, "%s: packet failed crc check (vcc: 0x%p)!\n",
+ __func__, vcc);
+ atomic_inc(&vcc->stats->rx_err);
+ goto out;
+ }

- if (sarb->len < pdu_length) {
- atm_rldbg(instance, "%s: bogus pdu_length %u (sarb->len: %u, vcc: 0x%p)!\n",
- __func__, pdu_length, sarb->len, vcc);
- atomic_inc(&vcc->stats->rx_err);
- goto out;
- }
+ vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);

- if (crc32_be(~0, sarb->tail - pdu_length, pdu_length) != 0xc704dd7b) {
- atm_rldbg(instance, "%s: packet failed crc check (vcc: 0x%p)!\n",
- __func__, vcc);
- atomic_inc(&vcc->stats->rx_err);
- goto out;
- }
+ if (!(skb = dev_alloc_skb(length))) {
+ if (printk_ratelimit())
+ atm_err(instance, "%s: no memory for skb (length: %u)!\n",
+ __func__, length);
+ atomic_inc(&vcc->stats->rx_drop);
+ goto out;
+ }

- vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);
+ vdbg("%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);

- if (!(skb = dev_alloc_skb(length))) {
- if (printk_ratelimit())
- atm_err(instance, "%s: no memory for skb (length: %u)!\n",
- __func__, length);
- atomic_inc(&vcc->stats->rx_drop);
- goto out;
- }
+ if (!atm_charge(vcc, skb->truesize)) {
+ atm_rldbg(instance, "%s: failed atm_charge (skb->truesize: %u)!\n",
+ __func__, skb->truesize);
+ dev_kfree_skb_any(skb);
+ goto out; /* atm_charge increments rx_drop */
+ }

- vdbg("%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);
+ memcpy(skb->data, sarb->tail - pdu_length, length);
+ __skb_put(skb, length);

- if (!atm_charge(vcc, skb->truesize)) {
- atm_rldbg(instance, "%s: failed atm_charge (skb->truesize: %u)!\n",
- __func__, skb->truesize);
- dev_kfree_skb_any(skb);
- goto out; /* atm_charge increments rx_drop */
- }
+ vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
+ __func__, skb, skb->len, skb->truesize);

- memcpy(skb->data, sarb->tail - pdu_length, length);
- __skb_put(skb, length);
+ PACKETDEBUG(skb->data, skb->len);

- vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
- __func__, skb, skb->len, skb->truesize);
+ vcc->push(vcc, skb);

- PACKETDEBUG(skb->data, skb->len);
+ atomic_inc(&vcc->stats->rx);
+ out:
+ skb_trim(sarb, 0);
+ }
+}

- vcc->push(vcc, skb);
+static void usbatm_extract_cells(struct usbatm_data *instance,
+ unsigned char *source, unsigned int avail_data)
+{
+ unsigned int stride = instance->rx_channel.stride;
+ unsigned int buf_usage = instance->buf_usage;

- atomic_inc(&vcc->stats->rx);
- out:
- skb_trim(sarb, 0);
+ /* extract cells from incoming data, taking into account that
+ * the length of avail data may not be a multiple of stride */
+
+ if (buf_usage > 0) {
+ /* we have a partially received atm cell */
+ unsigned char *cell_buf = instance->cell_buf;
+ unsigned int space_left = stride - buf_usage;
+
+ UDSL_ASSERT(buf_usage <= stride);
+
+ if (avail_data >= space_left) {
+ /* add new data and process cell */
+ memcpy(cell_buf + buf_usage, source, space_left);
+ source += space_left;
+ avail_data -= space_left;
+ usbatm_extract_one_cell(instance, cell_buf);
+ instance->buf_usage = 0;
+ } else {
+ /* not enough data to fill the cell */
+ memcpy(cell_buf + buf_usage, source, avail_data);
+ instance->buf_usage = buf_usage + avail_data;
+ return;
}
}
+
+ for (; avail_data >= stride; avail_data -= stride, source += stride)
+ usbatm_extract_one_cell(instance, source);
+
+ if (avail_data > 0) {
+ /* length was not a multiple of stride -
+ * save remaining data for next call */
+ memcpy(instance->cell_buf, source, avail_data);
+ instance->buf_usage = avail_data;
+ }
}


@@ -496,16 +529,40 @@
vdbg("%s: processing urb 0x%p", __func__, urb);

if (usb_pipeisoc(urb->pipe)) {
+ unsigned char *merge_start = NULL;
+ unsigned int merge_length = 0;
+ const unsigned int packet_size = instance->rx_channel.packet_size;
int i;
- for (i = 0; i < urb->number_of_packets; i++)
- if (!urb->iso_frame_desc[i].status)
- usbatm_extract_cells(instance,
- (u8 *)urb->transfer_buffer + urb->iso_frame_desc[i].offset,
- urb->iso_frame_desc[i].actual_length);
- }
- else
+
+ for (i = 0; i < urb->number_of_packets; i++) {
+ if (!urb->iso_frame_desc[i].status) {
+ unsigned int actual_length = urb->iso_frame_desc[i].actual_length;
+
+ UDSL_ASSERT(actual_length <= packet_size);
+
+ if (!merge_length)
+ merge_start = (unsigned char *)urb->transfer_buffer + urb->iso_frame_desc[i].offset;
+ merge_length += actual_length;
+ if (merge_length && (actual_length < packet_size)) {
+ usbatm_extract_cells(instance, merge_start, merge_length);
+ merge_length = 0;
+ }
+ } else {
+ atm_rldbg(instance, "%s: status %d in frame %d!\n", __func__, urb->status, i);
+ if (merge_length)
+ usbatm_extract_cells(instance, merge_start, merge_length);
+ merge_length = 0;
+ instance->buf_usage = 0;
+ }
+ }
+
+ if (merge_length)
+ usbatm_extract_cells(instance, merge_start, merge_length);
+ } else
if (!urb->status)
usbatm_extract_cells(instance, urb->transfer_buffer, urb->actual_length);
+ else
+ instance->buf_usage = 0;

if (usbatm_submit_urb(urb))
return;
@@ -797,6 +854,9 @@
vcc->dev_data = new;

tasklet_disable(&instance->rx_channel.tasklet);
+ instance->cached_vcc = new;
+ instance->cached_vpi = vpi;
+ instance->cached_vci = vci;
list_add(&new->list, &instance->vcc_list);
tasklet_enable(&instance->rx_channel.tasklet);

@@ -836,6 +896,11 @@
down(&instance->serialize); /* vs self, usbatm_atm_open, usbatm_usb_disconnect */

tasklet_disable(&instance->rx_channel.tasklet);
+ if (instance->cached_vcc == vcc_data) {
+ instance->cached_vcc = NULL;
+ instance->cached_vpi = ATM_VPI_UNSPEC;
+ instance->cached_vci = ATM_VCI_UNSPEC;
+ }
list_del(&vcc_data->list);
tasklet_enable(&instance->rx_channel.tasklet);

@@ -1146,6 +1211,16 @@
__func__, urb->transfer_buffer, urb->transfer_buffer_length, urb);
}

+ instance->cached_vpi = ATM_VPI_UNSPEC;
+ instance->cached_vci = ATM_VCI_UNSPEC;
+ instance->cell_buf = kmalloc(instance->rx_channel.stride, GFP_KERNEL);
+
+ if (!instance->cell_buf) {
+ dev_err(dev, "%s: no memory for cell buffer!\n", __func__);
+ error = -ENOMEM;
+ goto fail_unbind;
+ }
+
if (!(instance->flags & UDSL_SKIP_HEAVY_INIT) && driver->heavy_init) {
error = usbatm_heavy_init(instance);
} else {
@@ -1165,6 +1240,8 @@
if (instance->driver->unbind)
instance->driver->unbind(instance, intf);
fail_free:
+ kfree(instance->cell_buf);
+
for (i = 0; i < num_rcv_urbs + num_snd_urbs; i++) {
if (instance->urbs[i])
kfree(instance->urbs[i]->transfer_buffer);
@@ -1236,6 +1313,8 @@
usb_free_urb(instance->urbs[i]);
}

+ kfree(instance->cell_buf);
+
/* ATM finalize */
if (instance->atm_dev)
atm_dev_deregister(instance->atm_dev);
Index: Linux/drivers/usb/atm/usbatm.h
===================================================================
--- Linux.orig/drivers/usb/atm/usbatm.h 2006-01-13 09:12:53.000000000 +0100
+++ Linux/drivers/usb/atm/usbatm.h 2006-01-13 09:25:43.000000000 +0100
@@ -187,6 +187,13 @@
struct sk_buff_head sndqueue;
struct sk_buff *current_skb; /* being emptied */

+ struct usbatm_vcc_data *cached_vcc;
+ int cached_vci;
+ short cached_vpi;
+
+ unsigned char *cell_buf; /* holds partial rx cell */
+ unsigned int buf_usage;
+
struct urb *urbs[0];
};