3 files changed, 84 insertions, 20 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 1a134f9c64f3..3ae17840175c 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -1,6 +1,7 @@
 /*
  * USB Serial Converter Generic functions
  *
+ * Copyright (C) 2010 Johan Hovold (jhovold@gmail.com)
  * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
  *
  *      This program is free software; you can redistribute it and/or
@@ -143,6 +144,7 @@ static void generic_cleanup(struct usb_serial_port *port)
 {
         struct usb_serial *serial = port->serial;
         unsigned long flags;
+        int i;
 
         dbg("%s - port %d", __func__, port->number);
 
@@ -150,6 +152,8 @@ static void generic_cleanup(struct usb_serial_port *port)
                 /* shutdown any bulk transfers that might be going on */
                 if (port->bulk_out_size) {
                         usb_kill_urb(port->write_urb);
+                        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
+                                usb_kill_urb(port->write_urbs[i]);
 
                         spin_lock_irqsave(&port->lock, flags);
                         kfifo_reset_out(&port->write_fifo);
@@ -258,46 +262,56 @@ err_urb:
  * usb_serial_generic_write_start - kick off an URB write
  * @port:       Pointer to the &struct usb_serial_port data
  *
- * Returns the number of bytes queued on success. This will be zero if there
- * was nothing to send. Otherwise, it returns a negative errno value
+ * Returns zero on success, or a negative errno value
  */
 static int usb_serial_generic_write_start(struct usb_serial_port *port)
 {
-        int result;
-        int count;
+        struct urb *urb;
+        int count, result;
         unsigned long flags;
+        int i;
 
+        if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, &port->flags))
+                return 0;
+retry:
         spin_lock_irqsave(&port->lock, flags);
-        if (port->write_urb_busy || !kfifo_len(&port->write_fifo)) {
+        if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) {
+                clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
                 spin_unlock_irqrestore(&port->lock, flags);
                 return 0;
         }
-        port->write_urb_busy = 1;
+        i = (int)find_first_bit(&port->write_urbs_free,
+                                                ARRAY_SIZE(port->write_urbs));
         spin_unlock_irqrestore(&port->lock, flags);
 
+        urb = port->write_urbs[i];
         count = port->serial->type->prepare_write_buffer(port,
-                                        &port->write_urb->transfer_buffer,
-                                        port->bulk_out_size, NULL, 0);
-        usb_serial_debug_data(debug, &port->dev, __func__,
-                                count, port->write_urb->transfer_buffer);
-        port->write_urb->transfer_buffer_length = count;
-
-        /* send the data out the bulk port */
-        result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
+                                                &urb->transfer_buffer,
+                                                port->bulk_out_size, NULL, 0);
+        urb->transfer_buffer_length = count;
+        usb_serial_debug_data(debug, &port->dev, __func__, count,
+                                                urb->transfer_buffer);
+        result = usb_submit_urb(urb, GFP_ATOMIC);
         if (result) {
                 dev_err(&port->dev, "%s - error submitting urb: %d\n",
                                                 __func__, result);
-                /* don't have to grab the lock here, as we will
-                   retry if != 0 */
-                port->write_urb_busy = 0;
+                clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
                 return result;
         }
+        clear_bit(i, &port->write_urbs_free);
 
         spin_lock_irqsave(&port->lock, flags);
         port->tx_bytes += count;
         spin_unlock_irqrestore(&port->lock, flags);
 
-        return count;
+        /* Try sending off another urb, unless in irq context (in which case
+         * there will be no free urb). */
+        if (!in_irq())
+                goto retry;
+
+        clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
+
+        return 0;
 }
 
 /**
@@ -461,6 +475,7 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
         unsigned long flags;
         struct usb_serial_port *port = urb->context;
         int status = urb->status;
+        int i;
 
         dbg("%s - port %d", __func__, port->number);
 
@@ -472,9 +487,13 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
                 port->tx_urbs--;
                 spin_unlock_irqrestore(&port->lock, flags);
         } else {
+                for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
+                        if (port->write_urbs[i] == urb)
+                                break;
+
                 spin_lock_irqsave(&port->lock, flags);
                 port->tx_bytes -= urb->transfer_buffer_length;
-                port->write_urb_busy = 0;
+                set_bit(i, &port->write_urbs_free);
                 spin_unlock_irqrestore(&port->lock, flags);
 
                 if (status) {
@@ -576,7 +595,7 @@ int usb_serial_generic_resume(struct usb_serial *serial)
                                 c++;
                 }
 
-                if (port->write_urb) {
+                if (port->bulk_out_size) {
                         r = usb_serial_generic_write_start(port);
                         if (r < 0)
                                 c++;
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 8249fd8381fb..941c2d409f85 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -548,8 +548,12 @@ static void usb_serial_port_work(struct work_struct *work)
 
 static void kill_traffic(struct usb_serial_port *port)
 {
+        int i;
+
         usb_kill_urb(port->read_urb);
         usb_kill_urb(port->write_urb);
+        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
+                usb_kill_urb(port->write_urbs[i]);
         /*
          * This is tricky.
          * Some drivers submit the read_urb in the
@@ -568,6 +572,7 @@ static void kill_traffic(struct usb_serial_port *port)
 static void port_release(struct device *dev)
 {
         struct usb_serial_port *port = to_usb_serial_port(dev);
+        int i;
 
         dbg ("%s - %s", __func__, dev_name(dev));
 
@@ -582,6 +587,10 @@ static void port_release(struct device *dev)
         usb_free_urb(port->write_urb);
         usb_free_urb(port->interrupt_in_urb);
         usb_free_urb(port->interrupt_out_urb);
+        for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
+                usb_free_urb(port->write_urbs[i]);
+                kfree(port->bulk_out_buffers[i]);
+        }
         kfifo_free(&port->write_fifo);
         kfree(port->bulk_in_buffer);
         kfree(port->bulk_out_buffer);
@@ -920,6 +929,8 @@ int usb_serial_probe(struct usb_interface *interface,
         }
 
         for (i = 0; i < num_bulk_out; ++i) {
+                int j;
+
                 endpoint = bulk_out_endpoint[i];
                 port = serial->port[i];
                 port->write_urb = usb_alloc_urb(0, GFP_KERNEL);
@@ -945,6 +956,28 @@ int usb_serial_probe(struct usb_interface *interface,
                                         endpoint->bEndpointAddress),
                                 port->bulk_out_buffer, buffer_size,
                                 serial->type->write_bulk_callback, port);
+                for (j = 0; j < ARRAY_SIZE(port->write_urbs); ++j) {
+                        set_bit(j, &port->write_urbs_free);
+                        port->write_urbs[j] = usb_alloc_urb(0, GFP_KERNEL);
+                        if (!port->write_urbs[j]) {
+                                dev_err(&interface->dev,
+                                                "No free urbs available\n");
+                                goto probe_error;
+                        }
+                        port->bulk_out_buffers[j] = kmalloc(buffer_size,
+                                                                GFP_KERNEL);
+                        if (!port->bulk_out_buffers[j]) {
+                                dev_err(&interface->dev,
+                                        "Couldn't allocate bulk_out_buffer\n");
+                                goto probe_error;
+                        }
+                        usb_fill_bulk_urb(port->write_urbs[j], dev,
+                                        usb_sndbulkpipe(dev,
+                                                endpoint->bEndpointAddress),
+                                        port->bulk_out_buffers[j], buffer_size,
+                                        serial->type->write_bulk_callback,
+                                        port);
+                }
         }
 
         if (serial->type->read_int_callback) {
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index a4c99ea390e7..70b6d6b28997 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -35,6 +35,9 @@ enum port_dev_state {
         PORT_UNREGISTERING,
 };
 
+/* USB serial flags */
+#define USB_SERIAL_WRITE_BUSY   0
+
 /**
  * usb_serial_port: structure for the specific ports of a device.
  * @serial: pointer back to the struct usb_serial owner of this port.
@@ -60,10 +63,14 @@ 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
+ * @bulk_out_buffers: pointers to the bulk out buffers for this port
+ * @write_urbs: pointers to the bulk out urbs for this port
+ * @write_urbs_free: status bitmap the for bulk out urbs
  * @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.
+ * @flags: usb serial port flags
  * @write_wait: a wait_queue_head_t used by the port.
  * @work: work queue entry for the line discipline waking up.
  * @throttled: nonzero if the read urb is inactive to throttle the device
@@ -98,11 +105,16 @@ struct usb_serial_port {
         struct urb              *write_urb;
         struct kfifo            write_fifo;
         int                     write_urb_busy;
+
+        unsigned char           *bulk_out_buffers[2];
+        struct urb              *write_urbs[2];
+        unsigned long           write_urbs_free;
         __u8                    bulk_out_endpointAddress;
 
         int                     tx_bytes;
         int                     tx_urbs;
 
+        unsigned long           flags;
         wait_queue_head_t       write_wait;
         struct work_struct      work;
         char                    throttled;