1 files changed, 60 insertions, 19 deletions

diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c
index 32d70cc046e7..0eff19ceb7e1 100644
--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -45,6 +45,7 @@
 #include <linux/slab.h>
 #include <linux/timer.h>
 #include <linux/usb.h>
+#include <linux/wait.h>
 #include <sound/core.h>
 #include <sound/rawmidi.h>
 #include <sound/asequencer.h>
@@ -124,9 +125,10 @@ struct snd_usb_midi_out_endpoint {
                 struct snd_usb_midi_out_endpoint *ep;
         } urbs[OUTPUT_URBS];
         unsigned int active_urbs;
+        unsigned int drain_urbs;
         int max_transfer;               /* size of urb buffer */
         struct tasklet_struct tasklet;
-
+        unsigned int next_urb;
         spinlock_t buffer_lock;
 
         struct usbmidi_out_port {
@@ -145,6 +147,8 @@ struct snd_usb_midi_out_endpoint {
                 uint8_t data[2];
         } ports[0x10];
         int current_port;
+
+        wait_queue_head_t drain_wait;
 };
 
 struct snd_usb_midi_in_endpoint {
@@ -259,9 +263,15 @@ static void snd_usbmidi_out_urb_complete(struct urb* urb)
 {
         struct out_urb_context *context = urb->context;
         struct snd_usb_midi_out_endpoint* ep = context->ep;
+        unsigned int urb_index;
 
         spin_lock(&ep->buffer_lock);
-        ep->active_urbs &= ~(1 << (context - ep->urbs));
+        urb_index = context - ep->urbs;
+        ep->active_urbs &= ~(1 << urb_index);
+        if (unlikely(ep->drain_urbs)) {
+                ep->drain_urbs &= ~(1 << urb_index);
+                wake_up(&ep->drain_wait);
+        }
         spin_unlock(&ep->buffer_lock);
         if (urb->status < 0) {
                 int err = snd_usbmidi_urb_error(urb->status);
@@ -291,28 +301,28 @@ static void snd_usbmidi_do_output(struct snd_usb_midi_out_endpoint* ep)
                 return;
         }
 
+        urb_index = ep->next_urb;
         for (;;) {
-                urb = NULL;
-                for (urb_index = 0; urb_index < OUTPUT_URBS; ++urb_index)
-                        if (!(ep->active_urbs & (1 << urb_index))) {
-                                urb = ep->urbs[urb_index].urb;
+                if (!(ep->active_urbs & (1 << urb_index))) {
+                        urb = ep->urbs[urb_index].urb;
+                        urb->transfer_buffer_length = 0;
+                        ep->umidi->usb_protocol_ops->output(ep, urb);
+                        if (urb->transfer_buffer_length == 0)
                                 break;
-                        }
-                if (!urb)
-                        break;
-
-                urb->transfer_buffer_length = 0;
-                ep->umidi->usb_protocol_ops->output(ep, urb);
-                if (urb->transfer_buffer_length == 0)
-                        break;
 
-                dump_urb("sending", urb->transfer_buffer,
-                         urb->transfer_buffer_length);
-                urb->dev = ep->umidi->chip->dev;
-                if (snd_usbmidi_submit_urb(urb, GFP_ATOMIC) < 0)
+                        dump_urb("sending", urb->transfer_buffer,
+                                 urb->transfer_buffer_length);
+                        urb->dev = ep->umidi->chip->dev;
+                        if (snd_usbmidi_submit_urb(urb, GFP_ATOMIC) < 0)
+                                break;
+                        ep->active_urbs |= 1 << urb_index;
+                }
+                if (++urb_index >= OUTPUT_URBS)
+                        urb_index = 0;
+                if (urb_index == ep->next_urb)
                         break;
-                ep->active_urbs |= 1 << urb_index;
         }
+        ep->next_urb = urb_index;
         spin_unlock_irqrestore(&ep->buffer_lock, flags);
 }
 
@@ -913,6 +923,35 @@ static void snd_usbmidi_output_trigger(struct snd_rawmidi_substream *substream,
         }
 }
 
+static void snd_usbmidi_output_drain(struct snd_rawmidi_substream *substream)
+{
+        struct usbmidi_out_port* port = substream->runtime->private_data;
+        struct snd_usb_midi_out_endpoint *ep = port->ep;
+        unsigned int drain_urbs;
+        DEFINE_WAIT(wait);
+        long timeout = msecs_to_jiffies(50);
+
+        /*
+         * The substream buffer is empty, but some data might still be in the
+         * currently active URBs, so we have to wait for those to complete.
+         */
+        spin_lock_irq(&ep->buffer_lock);
+        drain_urbs = ep->active_urbs;
+        if (drain_urbs) {
+                ep->drain_urbs |= drain_urbs;
+                do {
+                        prepare_to_wait(&ep->drain_wait, &wait,
+                                        TASK_UNINTERRUPTIBLE);
+                        spin_unlock_irq(&ep->buffer_lock);
+                        timeout = schedule_timeout(timeout);
+                        spin_lock_irq(&ep->buffer_lock);
+                        drain_urbs &= ep->drain_urbs;
+                } while (drain_urbs && timeout);
+                finish_wait(&ep->drain_wait, &wait);
+        }
+        spin_unlock_irq(&ep->buffer_lock);
+}
+
 static int snd_usbmidi_input_open(struct snd_rawmidi_substream *substream)
 {
         return 0;
@@ -937,6 +976,7 @@ static struct snd_rawmidi_ops snd_usbmidi_output_ops = {
         .open = snd_usbmidi_output_open,
         .close = snd_usbmidi_output_close,
         .trigger = snd_usbmidi_output_trigger,
+        .drain = snd_usbmidi_output_drain,
 };
 
 static struct snd_rawmidi_ops snd_usbmidi_input_ops = {
@@ -1103,6 +1143,7 @@ static int snd_usbmidi_out_endpoint_create(struct snd_usb_midi* umidi,
 
         spin_lock_init(&ep->buffer_lock);
         tasklet_init(&ep->tasklet, snd_usbmidi_out_tasklet, (unsigned long)ep);
+        init_waitqueue_head(&ep->drain_wait);
 
         for (i = 0; i < 0x10; ++i)
                 if (ep_info->out_cables & (1 << i)) {