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Date: Tue, 14 Mar 2017 21:14:46 +0100
From: Tobias Herzog <t-herzog@....de>
To: oneukum@...e.com
Cc: gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] cdc-acm: reassemble fragmented notifications
USB devices may have very limitited endpoint packet sizes, so that
notifications can not be transferred within one single usb packet.
Reassembling of multiple packages may be necessary.
Signed-off-by: Tobias Herzog <t-herzog@....de>
---
drivers/usb/class/cdc-acm.c | 102 +++++++++++++++++++++++++++++++-------------
drivers/usb/class/cdc-acm.h | 2 +
2 files changed, 75 insertions(+), 29 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e35b150..40714fe 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -282,39 +282,13 @@ static DEVICE_ATTR(iCountryCodeRelDate, S_IRUGO, show_country_rel_date, NULL);
* Interrupt handlers for various ACM device responses
*/
-/* control interface reports status changes with "interrupt" transfers */
-static void acm_ctrl_irq(struct urb *urb)
+static void acm_process_notification(struct acm *acm, unsigned char *buf)
{
- struct acm *acm = urb->context;
- struct usb_cdc_notification *dr = urb->transfer_buffer;
- unsigned char *data;
int newctrl;
int difference;
- int retval;
- int status = urb->status;
+ struct usb_cdc_notification *dr = (struct usb_cdc_notification *)buf;
+ unsigned char *data = (unsigned char *)(dr + 1);
- switch (status) {
- case 0:
- /* success */
- break;
- case -ECONNRESET:
- case -ENOENT:
- case -ESHUTDOWN:
- /* this urb is terminated, clean up */
- dev_dbg(&acm->control->dev,
- "%s - urb shutting down with status: %d\n",
- __func__, status);
- return;
- default:
- dev_dbg(&acm->control->dev,
- "%s - nonzero urb status received: %d\n",
- __func__, status);
- goto exit;
- }
-
- usb_mark_last_busy(acm->dev);
-
- data = (unsigned char *)(dr + 1);
switch (dr->bNotificationType) {
case USB_CDC_NOTIFY_NETWORK_CONNECTION:
dev_dbg(&acm->control->dev,
@@ -363,8 +337,74 @@ static void acm_ctrl_irq(struct urb *urb)
__func__,
dr->bNotificationType, dr->wIndex,
dr->wLength, data[0], data[1]);
+ }
+}
+
+/* control interface reports status changes with "interrupt" transfers */
+static void acm_ctrl_irq(struct urb *urb)
+{
+ struct acm *acm = urb->context;
+ struct usb_cdc_notification *dr = urb->transfer_buffer;
+ unsigned int current_size = urb->actual_length;
+ unsigned int expected_size, copy_size;
+ int retval;
+ int status = urb->status;
+
+ switch (status) {
+ case 0:
+ /* success */
break;
+ case -ECONNRESET:
+ case -ENOENT:
+ case -ESHUTDOWN:
+ /* this urb is terminated, clean up */
+ kfree(acm->notification_buffer);
+ acm->notification_buffer = NULL;
+ dev_dbg(&acm->control->dev,
+ "%s - urb shutting down with status: %d\n",
+ __func__, status);
+ return;
+ default:
+ dev_dbg(&acm->control->dev,
+ "%s - nonzero urb status received: %d\n",
+ __func__, status);
+ goto exit;
}
+
+ usb_mark_last_busy(acm->dev);
+
+ if (acm->notification_buffer)
+ dr = (struct usb_cdc_notification *)acm->notification_buffer;
+
+ /* assume the first package contains at least two bytes */
+ expected_size = dr->wLength + 8;
+
+ if (current_size < expected_size) {
+ /* notification is transmitted framented, reassemble */
+ if (!acm->notification_buffer) {
+ acm->notification_buffer =
+ kmalloc(expected_size, GFP_ATOMIC);
+ acm->nb_index = 0;
+ }
+
+ copy_size = min(current_size,
+ expected_size - acm->nb_index);
+
+ memcpy(&acm->notification_buffer[acm->nb_index],
+ urb->transfer_buffer, copy_size);
+ acm->nb_index += copy_size;
+ current_size = acm->nb_index;
+ }
+
+ if (current_size < expected_size)
+ goto exit;
+
+ /* notification complete */
+ acm_process_notification(acm, (unsigned char *)dr);
+
+ kfree(acm->notification_buffer);
+ acm->notification_buffer = NULL;
+
exit:
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval && retval != -EPERM)
@@ -1488,6 +1528,8 @@ static int acm_probe(struct usb_interface *intf,
epctrl->bInterval ? epctrl->bInterval : 16);
acm->ctrlurb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
acm->ctrlurb->transfer_dma = acm->ctrl_dma;
+ acm->notification_buffer = NULL;
+ acm->nb_index = 0;
dev_info(&intf->dev, "ttyACM%d: USB ACM device\n", minor);
@@ -1580,6 +1622,8 @@ static void acm_disconnect(struct usb_interface *intf)
usb_free_coherent(acm->dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
acm_read_buffers_free(acm);
+ kfree(acm->notification_buffer);
+
if (!acm->combined_interfaces)
usb_driver_release_interface(&acm_driver, intf == acm->control ?
acm->data : acm->control);
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index c980f11..bc07fb2 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -98,6 +98,8 @@ struct acm {
struct acm_wb *putbuffer; /* for acm_tty_put_char() */
int rx_buflimit;
spinlock_t read_lock;
+ u8 *notification_buffer; /* to reassemble fragmented notifications */
+ unsigned int nb_index;
int write_used; /* number of non-empty write buffers */
int transmitting;
spinlock_t write_lock;
--
2.1.4
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