1 files changed, 139 insertions, 87 deletions

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 898a570319f1..84c0ee5ebd1e 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -23,6 +23,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/kfifo.h>
 
 #include <sound/core.h>
 #include <sound/initval.h>
@@ -55,7 +56,7 @@ static const char f_midi_longname[] = "MIDI Gadget";
  * USB <- IN endpoint  <- rawmidi
  */
 struct gmidi_in_port {
-	struct f_midi *midi;
+	struct snd_rawmidi_substream *substream;
 	int active;
 	uint8_t cable;
 	uint8_t state;
@@ -75,10 +76,9 @@ struct f_midi {
 	struct usb_ep		*in_ep, *out_ep;
 	struct snd_card		*card;
 	struct snd_rawmidi	*rmidi;
+	u8			ms_id;
 
-	struct snd_rawmidi_substream *in_substream[MAX_PORTS];
 	struct snd_rawmidi_substream *out_substream[MAX_PORTS];
-	struct gmidi_in_port	*in_port[MAX_PORTS];
 
 	unsigned long		out_triggered;
 	struct tasklet_struct	tasklet;
@@ -87,6 +87,11 @@ struct f_midi {
 	int index;
 	char *id;
 	unsigned int buflen, qlen;
+	/* This fifo is used as a buffer ring for pre-allocated IN usb_requests */
+	DECLARE_KFIFO_PTR(in_req_fifo, struct usb_request *);
+	unsigned int in_last_port;
+
+	struct gmidi_in_port	in_ports_array[/* in_ports */];
 };
 
 static inline struct f_midi *func_to_midi(struct usb_function *f)
@@ -94,7 +99,7 @@ static inline struct f_midi *func_to_midi(struct usb_function *f)
 	return container_of(f, struct f_midi, func);
 }
 
-static void f_midi_transmit(struct f_midi *midi, struct usb_request *req);
+static void f_midi_transmit(struct f_midi *midi);
 
 DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
 DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
@@ -201,12 +206,6 @@ static inline struct usb_request *midi_alloc_ep_req(struct usb_ep *ep,
 	return alloc_ep_req(ep, length, length);
 }
 
-static void free_ep_req(struct usb_ep *ep, struct usb_request *req)
-{
-	kfree(req->buf);
-	usb_ep_free_request(ep, req);
-}
-
 static const uint8_t f_midi_cin_length[] = {
 	0, 0, 2, 3, 3, 1, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1
 };
@@ -258,7 +257,8 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
 		} else if (ep == midi->in_ep) {
 			/* Our transmit completed. See if there's more to go.
 			 * f_midi_transmit eats req, don't queue it again. */
-			f_midi_transmit(midi, req);
+			req->length = 0;
+			f_midi_transmit(midi);
 			return;
 		}
 		break;
@@ -269,10 +269,12 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
 	case -ESHUTDOWN:	/* disconnect from host */
 		VDBG(cdev, "%s gone (%d), %d/%d\n", ep->name, status,
 				req->actual, req->length);
-		if (ep == midi->out_ep)
+		if (ep == midi->out_ep) {
 			f_midi_handle_out_data(ep, req);
-
-		free_ep_req(ep, req);
+			/* We don't need to free IN requests because it's handled
+			 * by the midi->in_req_fifo. */
+			free_ep_req(ep, req);
+		}
 		return;
 
 	case -EOVERFLOW:	/* buffer overrun on read means that
@@ -324,12 +326,11 @@ static int f_midi_start_ep(struct f_midi *midi,
 static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 {
 	struct f_midi *midi = func_to_midi(f);
-	struct usb_composite_dev *cdev = f->config->cdev;
 	unsigned i;
 	int err;
 
-	/* For Control Device interface we do nothing */
-	if (intf == 0)
+	/* we only set alt for MIDIStreaming interface */
+	if (intf != midi->ms_id)
 		return 0;
 
 	err = f_midi_start_ep(midi, f, midi->in_ep);
@@ -340,23 +341,19 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 	if (err)
 		return err;
 
-	usb_ep_disable(midi->out_ep);
+	/* pre-allocate write usb requests to use on f_midi_transmit. */
+	while (kfifo_avail(&midi->in_req_fifo)) {
+		struct usb_request *req =
+			midi_alloc_ep_req(midi->in_ep, midi->buflen);
 
-	err = config_ep_by_speed(midi->gadget, f, midi->out_ep);
-	if (err) {
-		ERROR(cdev, "can't configure %s: %d\n",
-		      midi->out_ep->name, err);
-		return err;
-	}
+		if (req == NULL)
+			return -ENOMEM;
 
-	err = usb_ep_enable(midi->out_ep);
-	if (err) {
-		ERROR(cdev, "can't start %s: %d\n",
-		      midi->out_ep->name, err);
-		return err;
-	}
+		req->length = 0;
+		req->complete = f_midi_complete;
 
-	midi->out_ep->driver_data = midi;
+		kfifo_put(&midi->in_req_fifo, req);
+	}
 
 	/* allocate a bunch of read buffers and queue them all at once. */
 	for (i = 0; i < midi->qlen && err == 0; i++) {
@@ -368,9 +365,10 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 		req->complete = f_midi_complete;
 		err = usb_ep_queue(midi->out_ep, req, GFP_ATOMIC);
 		if (err) {
-			ERROR(midi, "%s queue req: %d\n",
+			ERROR(midi, "%s: couldn't enqueue request: %d\n",
 				    midi->out_ep->name, err);
 			free_ep_req(midi->out_ep, req);
+			return err;
 		}
 	}
 
@@ -381,6 +379,7 @@ static void f_midi_disable(struct usb_function *f)
 {
 	struct f_midi *midi = func_to_midi(f);
 	struct usb_composite_dev *cdev = f->config->cdev;
+	struct usb_request *req = NULL;
 
 	DBG(cdev, "disable\n");
 
@@ -390,6 +389,10 @@ static void f_midi_disable(struct usb_function *f)
 	 */
 	usb_ep_disable(midi->in_ep);
 	usb_ep_disable(midi->out_ep);
+
+	/* release IN requests */
+	while (kfifo_get(&midi->in_req_fifo, &req))
+		free_ep_req(midi->in_ep, req);
 }
 
 static int f_midi_snd_free(struct snd_device *device)
@@ -511,69 +514,124 @@ static void f_midi_transmit_byte(struct usb_request *req,
 	}
 }
 
-static void f_midi_transmit(struct f_midi *midi, struct usb_request *req)
+static void f_midi_drop_out_substreams(struct f_midi *midi)
 {
-	struct usb_ep *ep = midi->in_ep;
-	int i;
+	unsigned int i;
 
-	if (!ep)
-		return;
+	for (i = 0; i < midi->in_ports; i++) {
+		struct gmidi_in_port *port = midi->in_ports_array + i;
+		struct snd_rawmidi_substream *substream = port->substream;
+		if (port->active && substream)
+			snd_rawmidi_drop_output(substream);
+	}
+}
 
-	if (!req)
-		req = midi_alloc_ep_req(ep, midi->buflen);
+static int f_midi_do_transmit(struct f_midi *midi, struct usb_ep *ep)
+{
+	struct usb_request *req = NULL;
+	unsigned int len, i;
+	bool active = false;
+	int err;
 
-	if (!req) {
-		ERROR(midi, "%s: alloc_ep_request failed\n", __func__);
-		return;
+	/*
+	 * We peek the request in order to reuse it if it fails to enqueue on
+	 * its endpoint
+	 */
+	len = kfifo_peek(&midi->in_req_fifo, &req);
+	if (len != 1) {
+		ERROR(midi, "%s: Couldn't get usb request\n", __func__);
+		return -1;
 	}
-	req->length = 0;
-	req->complete = f_midi_complete;
 
-	for (i = 0; i < MAX_PORTS; i++) {
-		struct gmidi_in_port *port = midi->in_port[i];
-		struct snd_rawmidi_substream *substream = midi->in_substream[i];
+	/*
+	 * If buffer overrun, then we ignore this transmission.
+	 * IMPORTANT: This will cause the user-space rawmidi device to block
+	 * until a) usb requests have been completed or b) snd_rawmidi_write()
+	 * times out.
+	 */
+	if (req->length > 0)
+		return 0;
+
+	for (i = midi->in_last_port; i < midi->in_ports; ++i) {
+		struct gmidi_in_port *port = midi->in_ports_array + i;
+		struct snd_rawmidi_substream *substream = port->substream;
 
-		if (!port || !port->active || !substream)
+		if (!port->active || !substream)
 			continue;
 
 		while (req->length + 3 < midi->buflen) {
 			uint8_t b;
+
 			if (snd_rawmidi_transmit(substream, &b, 1) != 1) {
 				port->active = 0;
 				break;
 			}
 			f_midi_transmit_byte(req, port, b);
 		}
+
+		active = !!port->active;
+		if (active)
+			break;
 	}
+	midi->in_last_port = active ? i : 0;
 
-	if (req->length > 0 && ep->enabled) {
-		int err;
+	if (req->length <= 0)
+		goto done;
 
-		err = usb_ep_queue(ep, req, GFP_ATOMIC);
-		if (err < 0)
-			ERROR(midi, "%s queue req: %d\n",
-			      midi->in_ep->name, err);
+	err = usb_ep_queue(ep, req, GFP_ATOMIC);
+	if (err < 0) {
+		ERROR(midi, "%s failed to queue req: %d\n",
+		      midi->in_ep->name, err);
+		req->length = 0; /* Re-use request next time. */
 	} else {
-		free_ep_req(ep, req);
+		/* Upon success, put request at the back of the queue. */
+		kfifo_skip(&midi->in_req_fifo);
+		kfifo_put(&midi->in_req_fifo, req);
 	}
+
+done:
+	return active;
+}
+
+static void f_midi_transmit(struct f_midi *midi)
+{
+	struct usb_ep *ep = midi->in_ep;
+	int ret;
+
+	/* We only care about USB requests if IN endpoint is enabled */
+	if (!ep || !ep->enabled)
+		goto drop_out;
+
+	do {
+		ret = f_midi_do_transmit(midi, ep);
+		if (ret < 0)
+			goto drop_out;
+	} while (ret);
+
+	return;
+
+drop_out:
+	f_midi_drop_out_substreams(midi);
 }
 
 static void f_midi_in_tasklet(unsigned long data)
 {
 	struct f_midi *midi = (struct f_midi *) data;
-	f_midi_transmit(midi, NULL);
+	f_midi_transmit(midi);
 }
 
 static int f_midi_in_open(struct snd_rawmidi_substream *substream)
 {
 	struct f_midi *midi = substream->rmidi->private_data;
+	struct gmidi_in_port *port;
 
-	if (!midi->in_port[substream->number])
+	if (substream->number >= midi->in_ports)
 		return -EINVAL;
 
 	VDBG(midi, "%s()\n", __func__);
-	midi->in_substream[substream->number] = substream;
-	midi->in_port[substream->number]->state = STATE_UNKNOWN;
+	port = midi->in_ports_array + substream->number;
+	port->substream = substream;
+	port->state = STATE_UNKNOWN;
 	return 0;
 }
 
@@ -589,11 +647,11 @@ static void f_midi_in_trigger(struct snd_rawmidi_substream *substream, int up)
 {
 	struct f_midi *midi = substream->rmidi->private_data;
 
-	if (!midi->in_port[substream->number])
+	if (substream->number >= midi->in_ports)
 		return;
 
 	VDBG(midi, "%s() %d\n", __func__, up);
-	midi->in_port[substream->number]->active = up;
+	midi->in_ports_array[substream->number].active = up;
 	if (up)
 		tasklet_hi_schedule(&midi->tasklet);
 }
@@ -687,6 +745,7 @@ static int f_midi_register_card(struct f_midi *midi)
 		goto fail;
 	}
 	midi->rmidi = rmidi;
+	midi->in_last_port = 0;
 	strcpy(rmidi->name, card->shortname);
 	rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
 			    SNDRV_RAWMIDI_INFO_INPUT |
@@ -755,6 +814,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f)
 		goto fail;
 	ms_interface_desc.bInterfaceNumber = status;
 	ac_header_desc.baInterfaceNr[0] = status;
+	midi->ms_id = status;
 
 	status = -ENODEV;
 
@@ -1067,14 +1127,12 @@ static void f_midi_free(struct usb_function *f)
 {
 	struct f_midi *midi;
 	struct f_midi_opts *opts;
-	int i;
 
 	midi = func_to_midi(f);
 	opts = container_of(f->fi, struct f_midi_opts, func_inst);
 	kfree(midi->id);
 	mutex_lock(&opts->lock);
-	for (i = opts->in_ports - 1; i >= 0; --i)
-		kfree(midi->in_port[i]);
+	kfifo_free(&midi->in_req_fifo);
 	kfree(midi);
 	--opts->refcnt;
 	mutex_unlock(&opts->lock);
@@ -1101,7 +1159,7 @@ static void f_midi_unbind(struct usb_configuration *c, struct usb_function *f)
 
 static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 {
-	struct f_midi *midi;
+	struct f_midi *midi = NULL;
 	struct f_midi_opts *opts;
 	int status, i;
 
@@ -1110,37 +1168,26 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	mutex_lock(&opts->lock);
 	/* sanity check */
 	if (opts->in_ports > MAX_PORTS || opts->out_ports > MAX_PORTS) {
-		mutex_unlock(&opts->lock);
-		return ERR_PTR(-EINVAL);
+		status = -EINVAL;
+		goto setup_fail;
 	}
 
 	/* allocate and initialize one new instance */
-	midi = kzalloc(sizeof(*midi), GFP_KERNEL);
+	midi = kzalloc(
+		sizeof(*midi) + opts->in_ports * sizeof(*midi->in_ports_array),
+		GFP_KERNEL);
 	if (!midi) {
-		mutex_unlock(&opts->lock);
-		return ERR_PTR(-ENOMEM);
+		status = -ENOMEM;
+		goto setup_fail;
 	}
 
-	for (i = 0; i < opts->in_ports; i++) {
-		struct gmidi_in_port *port = kzalloc(sizeof(*port), GFP_KERNEL);
-
-		if (!port) {
-			status = -ENOMEM;
-			mutex_unlock(&opts->lock);
-			goto setup_fail;
-		}
-
-		port->midi = midi;
-		port->active = 0;
-		port->cable = i;
-		midi->in_port[i] = port;
-	}
+	for (i = 0; i < opts->in_ports; i++)
+		midi->in_ports_array[i].cable = i;
 
 	/* set up ALSA midi devices */
 	midi->id = kstrdup(opts->id, GFP_KERNEL);
 	if (opts->id && !midi->id) {
 		status = -ENOMEM;
-		mutex_unlock(&opts->lock);
 		goto setup_fail;
 	}
 	midi->in_ports = opts->in_ports;
@@ -1148,6 +1195,12 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	midi->index = opts->index;
 	midi->buflen = opts->buflen;
 	midi->qlen = opts->qlen;
+	midi->in_last_port = 0;
+
+	status = kfifo_alloc(&midi->in_req_fifo, midi->qlen, GFP_KERNEL);
+	if (status)
+		goto setup_fail;
+
 	++opts->refcnt;
 	mutex_unlock(&opts->lock);
 
@@ -1161,8 +1214,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
 	return &midi->func;
 
 setup_fail:
-	for (--i; i >= 0; i--)
-		kfree(midi->in_port[i]);
+	mutex_unlock(&opts->lock);
 	kfree(midi);
 	return ERR_PTR(status);
 }