[PATCH] USBATM: handle urbs containing partial cells

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@free.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 182 insertions, 96 deletions

diff --git a/drivers/usb/atm/usbatm.c b/drivers/usb/atm/usbatm.c
index 923f2d9269b..341430fbaf9 100644
--- a/drivers/usb/atm/usbatm.c
+++ b/drivers/usb/atm/usbatm.c
@@ -296,126 +296,159 @@ static inline struct usbatm_vcc_data *usbatm_find_vcc(struct usbatm_data *instan
         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);
-                        atomic_inc(&vcc->stats->rx_err);
-                        continue;
-                }
+        sarb = instance->cached_vcc->sarb;
 
-                sarb = 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);
+        }
 
-                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);
 
-                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;
 
-                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];
 
-                        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;
+                }
 
-                        /* 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;
-                        }
+                pdu_length = usbatm_pdu_length(length);
 
-                        pdu_length = usbatm_pdu_length(length);
+                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;
+                }
 
-                        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;
-                        }
+                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 (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;
-                        }
+                vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);
 
-                        vdbg("%s: got packet (length: %u, pdu_length: %u, vcc: 0x%p)", __func__, length, pdu_length, vcc);
+                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 (!(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: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);
 
-                        vdbg("%s: allocated new sk_buff (skb: 0x%p, skb->truesize: %u)", __func__, skb, skb->truesize);
+                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 */
+                }
 
-                        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 */
-                        }
+                memcpy(skb->data, sarb->tail - pdu_length, length);
+                __skb_put(skb, length);
 
-                        memcpy(skb->data, sarb->tail - pdu_length, length);
-                        __skb_put(skb, length);
+                vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
+                     __func__, skb, skb->len, skb->truesize);
 
-                        vdbg("%s: sending skb 0x%p, skb->len %u, skb->truesize %u",
-                             __func__, skb, skb->len, skb->truesize);
+                PACKETDEBUG(skb->data, skb->len);
 
-                        PACKETDEBUG(skb->data, skb->len);
+                vcc->push(vcc, skb);
 
-                        vcc->push(vcc, skb);
+                atomic_inc(&vcc->stats->rx);
+        out:
+                skb_trim(sarb, 0);
+        }
+}
 
-                        atomic_inc(&vcc->stats->rx);
-                out:
-                        skb_trim(sarb, 0);
+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;
+
+        /* 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 @@ static void usbatm_rx_process(unsigned long data)
                 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 @@ static int usbatm_atm_open(struct atm_vcc *vcc)
         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 @@ static void usbatm_atm_close(struct atm_vcc *vcc)
         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 @@ int usbatm_usb_probe(struct usb_interface *intf, const struct usb_device_id *id,
                      __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 @@ int usbatm_usb_probe(struct usb_interface *intf, const struct usb_device_id *id,
         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 @@ void usbatm_usb_disconnect(struct usb_interface *intf)
                 usb_free_urb(instance->urbs[i]);
         }
 
+        kfree(instance->cell_buf);
+
         /* ATM finalize */
         if (instance->atm_dev)
                 atm_dev_deregister(instance->atm_dev);
diff --git a/drivers/usb/atm/usbatm.h b/drivers/usb/atm/usbatm.h
index 0e2caa0967c..bdff534b941 100644
--- a/drivers/usb/atm/usbatm.h
+++ b/drivers/usb/atm/usbatm.h
@@ -187,6 +187,13 @@ struct usbatm_data {
         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];
 };