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Commit 2d19cdc1 authored by Jerry Zhang's avatar Jerry Zhang Committed by Felipe Balbi
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usb: gadget: f_midi: Use snd_card_free_when_closed with refcount 



Currenly, f_midi_free uses snd_card_free, which will wait
until the user has released the sound card before
returning. However, if the user doesn't release the sound
card, then f_midi_free can block for an arbitrary amount
of time, which also blocks any gadget operations on that
thread.

Instead, we can use snd_card_free_when_closed which returns
before all handles are released. Since f_midi can be
accessed through rmidi if usb_put_function is called before
release_card_device, add refcounting to f_midi_free and
have rawmidi's private free call it. The f_midi memory
is only kfreed when usb_put_function and release_card_device
have both been called.

Signed-off-by: default avatarJerry Zhang <zhangjerry@google.com>
Signed-off-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
parent 24cf3459

drivers/usb/gadget/function/f_midi.c

+17 −5
Original line number Diff line number Diff line
@@ -98,6 +98,7 @@ struct f_midi { 
	DECLARE_KFIFO_PTR(in_req_fifo, struct usb_request *);

	spinlock_t transmit_lock;

	unsigned int in_last_port;

	unsigned char free_ref;



	struct gmidi_in_port	in_ports_array[/* in_ports */];

};
@@ -108,6 +109,7 @@ static inline struct f_midi *func_to_midi(struct usb_function *f) 
}



static void f_midi_transmit(struct f_midi *midi);

static void f_midi_rmidi_free(struct snd_rawmidi *rmidi);



DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);

DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
@@ -832,6 +834,8 @@ static int f_midi_register_card(struct f_midi *midi) 
			    SNDRV_RAWMIDI_INFO_INPUT |

			    SNDRV_RAWMIDI_INFO_DUPLEX;

	rmidi->private_data = midi;

	rmidi->private_free = f_midi_rmidi_free;

	midi->free_ref++;



	/*

	 * Yes, rawmidi OUTPUT = USB IN, and rawmidi INPUT = USB OUT.
@@ -1233,14 +1237,21 @@ static void f_midi_free(struct usb_function *f) 


	midi = func_to_midi(f);

	opts = container_of(f->fi, struct f_midi_opts, func_inst);

	kfree(midi->id);

	mutex_lock(&opts->lock);

	if (!--midi->free_ref) {

		kfree(midi->id);

		kfifo_free(&midi->in_req_fifo);

		kfree(midi);

		--opts->refcnt;

	}

	mutex_unlock(&opts->lock);

}



static void f_midi_rmidi_free(struct snd_rawmidi *rmidi)

{

	f_midi_free(rmidi->private_data);

}



static void f_midi_unbind(struct usb_configuration *c, struct usb_function *f)

{

	struct usb_composite_dev *cdev = f->config->cdev;
@@ -1255,7 +1266,7 @@ static void f_midi_unbind(struct usb_configuration *c, struct usb_function *f) 
	card = midi->card;

	midi->card = NULL;

	if (card)

		snd_card_free(card);

		snd_card_free_when_closed(card);



	usb_free_all_descriptors(f);

}
@@ -1299,6 +1310,7 @@ static struct usb_function *f_midi_alloc(struct usb_function_instance *fi) 
	midi->buflen = opts->buflen;

	midi->qlen = opts->qlen;

	midi->in_last_port = 0;

	midi->free_ref = 1;



	status = kfifo_alloc(&midi->in_req_fifo, midi->qlen, GFP_KERNEL);

	if (status)