2 files changed, 62 insertions, 79 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index be52c748bccb..ad4823bbfa19 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -25,6 +25,8 @@
 
 static int debug;
 
+#define MAX_TX_URBS             40
+
 #ifdef CONFIG_USB_SERIAL_GENERIC
 
 static int generic_probe(struct usb_interface *interface,
@@ -172,78 +174,63 @@ static int usb_serial_multi_urb_write(struct tty_struct *tty,
         struct urb *urb;
         unsigned char *buffer;
         int status;
-        int towrite;
-        int bwrite = 0;
-
-        dbg("%s - port %d", __func__, port->number);
-
-        if (count == 0)
-                dbg("%s - write request of 0 bytes", __func__);
 
-        while (count > 0) {
-                towrite = (count > port->bulk_out_size) ?
-                        port->bulk_out_size : count;
-                spin_lock_irqsave(&port->lock, flags);
-                if (port->urbs_in_flight >
-                    port->serial->type->max_in_flight_urbs) {
-                        spin_unlock_irqrestore(&port->lock, flags);
-                        dbg("%s - write limit hit", __func__);
-                        return bwrite;
-                }
-                port->tx_bytes_flight += towrite;
-                port->urbs_in_flight++;
+        spin_lock_irqsave(&port->lock, flags);
+        if (port->tx_urbs == MAX_TX_URBS) {
                 spin_unlock_irqrestore(&port->lock, flags);
+                dbg("%s - write limit hit", __func__);
+                return 0;
+        }
+        port->tx_urbs++;
+        spin_unlock_irqrestore(&port->lock, flags);
 
-                buffer = kmalloc(towrite, GFP_ATOMIC);
-                if (!buffer) {
-                        dev_err(&port->dev,
-                        "%s ran out of kernel memory for urb ...\n", __func__);
-                        goto error_no_buffer;
-                }
+        urb = usb_alloc_urb(0, GFP_ATOMIC);
+        if (!urb) {
+                dev_err(&port->dev, "%s - no free urbs available\n", __func__);
+                status = -ENOMEM;
+                goto err_urb;
+        }
 
-                urb = usb_alloc_urb(0, GFP_ATOMIC);
-                if (!urb) {
-                        dev_err(&port->dev, "%s - no more free urbs\n",
+        count = min_t(int, count, PAGE_SIZE);
+        buffer = kmalloc(count, GFP_ATOMIC);
+        if (!buffer) {
+                dev_err(&port->dev, "%s - could not allocate buffer\n",
                                 __func__);
-                        goto error_no_urb;
-                }
+                status = -ENOMEM;
+                goto err_buf;
+        }
 
-                /* Copy data */
-                memcpy(buffer, buf + bwrite, towrite);
-                usb_serial_debug_data(debug, &port->dev, __func__,
-                                      towrite, buffer);
-                /* fill the buffer and send it */
-                usb_fill_bulk_urb(urb, port->serial->dev,
+        memcpy(buffer, buf, count);
+        usb_serial_debug_data(debug, &port->dev, __func__, count, buffer);
+        usb_fill_bulk_urb(urb, port->serial->dev,
                         usb_sndbulkpipe(port->serial->dev,
                                         port->bulk_out_endpointAddress),
-                        buffer, towrite,
+                        buffer, count,
                         port->serial->type->write_bulk_callback, port);
 
-                status = usb_submit_urb(urb, GFP_ATOMIC);
-                if (status) {
-                        dev_err(&port->dev, "%s - error submitting urb: %d\n",
+        status = usb_submit_urb(urb, GFP_ATOMIC);
+        if (status) {
+                dev_err(&port->dev, "%s - error submitting urb: %d\n",
                                 __func__, status);
-                        goto error;
-                }
-
-                /* This urb is the responsibility of the host driver now */
-                usb_free_urb(urb);
-                dbg("%s write: %d", __func__, towrite);
-                count -= towrite;
-                bwrite += towrite;
+                goto err;
         }
-        return bwrite;
+        spin_lock_irqsave(&port->lock, flags);
+        port->tx_bytes += urb->transfer_buffer_length;
+        spin_unlock_irqrestore(&port->lock, flags);
 
-error:
         usb_free_urb(urb);
-error_no_urb:
+
+        return count;
+err:
         kfree(buffer);
-error_no_buffer:
+err_buf:
+        usb_free_urb(urb);
+err_urb:
         spin_lock_irqsave(&port->lock, flags);
-        port->urbs_in_flight--;
-        port->tx_bytes_flight -= towrite;
+        port->tx_urbs--;
         spin_unlock_irqrestore(&port->lock, flags);
-        return bwrite;
+
+        return status;
 }
 
 /**
@@ -286,7 +273,7 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
         }
 
         spin_lock_irqsave(&port->lock, flags);
-        port->tx_bytes_flight += count;
+        port->tx_bytes += count;
         spin_unlock_irqrestore(&port->lock, flags);
 
         return count;
@@ -318,9 +305,8 @@ int usb_serial_generic_write(struct tty_struct *tty,
         if (!count)
                 return 0;
 
-        if (serial->type->max_in_flight_urbs)
-                return usb_serial_multi_urb_write(tty, port,
-                                                  buf, count);
+        if (serial->type->multi_urb_write)
+                return usb_serial_multi_urb_write(tty, port, buf, count);
 
         count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
         result = usb_serial_generic_write_start(port);
@@ -337,7 +323,7 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
         struct usb_serial_port *port = tty->driver_data;
         struct usb_serial *serial = port->serial;
         unsigned long flags;
-        int room = 0;
+        int room;
 
         dbg("%s - port %d", __func__, port->number);
 
@@ -345,14 +331,10 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
                 return 0;
 
         spin_lock_irqsave(&port->lock, flags);
-        if (serial->type->max_in_flight_urbs) {
-                if (port->urbs_in_flight < serial->type->max_in_flight_urbs)
-                        room = port->bulk_out_size *
-                                (serial->type->max_in_flight_urbs -
-                                 port->urbs_in_flight);
-        } else {
+        if (serial->type->multi_urb_write)
+                room = (MAX_TX_URBS - port->tx_urbs) * PAGE_SIZE;
+        else
                 room = kfifo_avail(&port->write_fifo);
-        }
         spin_unlock_irqrestore(&port->lock, flags);
 
         dbg("%s - returns %d", __func__, room);
@@ -372,10 +354,10 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
                 return 0;
 
         spin_lock_irqsave(&port->lock, flags);
-        if (serial->type->max_in_flight_urbs)
-                chars = port->tx_bytes_flight;
+        if (serial->type->multi_urb_write)
+                chars = port->tx_bytes;
         else
-                chars = kfifo_len(&port->write_fifo) + port->tx_bytes_flight;
+                chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
         spin_unlock_irqrestore(&port->lock, flags);
 
         dbg("%s - returns %d", __func__, chars);
@@ -461,18 +443,16 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
 
         dbg("%s - port %d", __func__, port->number);
 
-        if (port->serial->type->max_in_flight_urbs) {
+        if (port->serial->type->multi_urb_write) {
                 kfree(urb->transfer_buffer);
 
                 spin_lock_irqsave(&port->lock, flags);
-                --port->urbs_in_flight;
-                port->tx_bytes_flight -= urb->transfer_buffer_length;
-                if (port->urbs_in_flight < 0)
-                        port->urbs_in_flight = 0;
+                port->tx_bytes -= urb->transfer_buffer_length;
+                port->tx_urbs--;
                 spin_unlock_irqrestore(&port->lock, flags);
         } else {
                 spin_lock_irqsave(&port->lock, flags);
-                port->tx_bytes_flight -= urb->transfer_buffer_length;
+                port->tx_bytes -= urb->transfer_buffer_length;
                 port->write_urb_busy = 0;
                 spin_unlock_irqrestore(&port->lock, flags);
 
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index ff8872eba3ac..2a3283761600 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -60,6 +60,8 @@ enum port_dev_state {
  * @write_urb: pointer to the bulk out struct urb for this port.
  * @write_fifo: kfifo used to buffer outgoing data
  * @write_urb_busy: port`s writing status
+ * @tx_bytes: number of bytes currently in host stack queues
+ * @tx_urbs: number of urbs currently in host stack queues
  * @bulk_out_endpointAddress: endpoint address for the bulk out pipe for this
  *      port.
  * @write_wait: a wait_queue_head_t used by the port.
@@ -98,8 +100,8 @@ struct usb_serial_port {
         int                     write_urb_busy;
         __u8                    bulk_out_endpointAddress;
 
-        int                     tx_bytes_flight;
-        int                     urbs_in_flight;
+        int                     tx_bytes;
+        int                     tx_urbs;
 
         wait_queue_head_t       write_wait;
         struct work_struct      work;
@@ -223,7 +225,8 @@ struct usb_serial_driver {
         struct device_driver    driver;
         struct usb_driver       *usb_driver;
         struct usb_dynids       dynids;
-        int                     max_in_flight_urbs;
+
+        unsigned char           multi_urb_write:1;
 
         size_t                  bulk_in_size;
         size_t                  bulk_out_size;