usb: gadget: f_midi: use flexible array member for gmidi_in_port elements

Reduce number of allocations, simplify memory management and reduce
memory usage by stacking the gmidi_in_port elements at the end of the
f_midi structure using a flexible array.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 896f02c..8a3c8c4 100644 (file)
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -79,7 +79,6 @@ struct f_midi {
 
        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;
@@ -91,6 +90,8 @@ struct f_midi {
        /* 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)
@@ -517,24 +518,17 @@ static void f_midi_drop_out_substreams(struct f_midi *midi)
 {
        unsigned int i;
 
-       for (i = 0; i < MAX_PORTS; i++) {
-               struct gmidi_in_port *port = midi->in_port[i];
+       for (i = 0; i < midi->in_ports; i++) {
+               struct gmidi_in_port *port = midi->in_ports_array + i;
                struct snd_rawmidi_substream *substream = midi->in_substream[i];
-
-               if (!port)
-                       break;
-
-               if (!port->active || !substream)
-                       continue;
-
-               snd_rawmidi_drop_output(substream);
+               if (port->active && substream)
+                       snd_rawmidi_drop_output(substream);
        }
 }
 
 static int f_midi_do_transmit(struct f_midi *midi, struct usb_ep *ep)
 {
        struct usb_request *req = NULL;
-       struct gmidi_in_port *port;
        unsigned int len, i;
        bool active = false;
        int err;
@@ -558,9 +552,10 @@ static int f_midi_do_transmit(struct f_midi *midi, struct usb_ep *ep)
        if (req->length > 0)
                return 0;
 
-       i = midi->in_last_port;
-       for (; i < MAX_PORTS && (port = midi->in_port[i]); ++i) {
+       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 = midi->in_substream[i];
+
                if (!port->active || !substream)
                        continue;
 
@@ -629,12 +624,12 @@ static int f_midi_in_open(struct snd_rawmidi_substream *substream)
 {
        struct f_midi *midi = substream->rmidi->private_data;
 
-       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;
+       midi->in_ports_array[substream->number].state = STATE_UNKNOWN;
        return 0;
 }
 
@@ -650,11 +645,11 @@ 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);
 }
@@ -1130,14 +1125,11 @@ 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;
@@ -1179,25 +1171,16 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi)
        }
 
        /* 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);
        }
 
-       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->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);
@@ -1230,8 +1213,6 @@ 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]);
        kfree(midi);
        return ERR_PTR(status);
 }