Currently, 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. Also make use of refcnt in freeing
f_midi_opts. The opts are only freed after the config
items are released and all associated f_midi functions
are freed.
Signed-off-by: Jerry Zhang <zhangjerry@xxxxxxxxxx>
---
I see that this patch is already in Greg's tree. Can it still
be updated, or should I submit these changes as a new patch?
Changelog since V1:
- Added f_midi_opts refcounting
- Fixed compile error
drivers/usb/gadget/function/f_midi.c | 46 ++++++++++++++++++++++++++++--------
1 file changed, 36 insertions(+), 10 deletions(-)
diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index a5719f271bf0..93464b42770c 100644
--- a/drivers/usb/gadget/function/f_midi.c
+++ b/drivers/usb/gadget/function/f_midi.c
@@ -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 +109,8 @@ 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);
+static void f_midi_free_inst(struct usb_function_instance *f);
DECLARE_UAC_AC_HEADER_DESCRIPTOR(1);
DECLARE_USB_MIDI_OUT_JACK_DESCRIPTOR(1);
@@ -818,6 +821,8 @@ 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.
@@ -1062,7 +1067,7 @@ static ssize_t f_midi_opts_##name##_store(struct config_item *item, \
u32 num; \
\
mutex_lock(&opts->lock); \
- if (opts->refcnt) { \
+ if (opts->refcnt > 1) { \
ret = -EBUSY; \
goto end; \
} \
@@ -1117,7 +1122,7 @@ static ssize_t f_midi_opts_id_store(struct config_item *item,
char *c;
mutex_lock(&opts->lock);
- if (opts->refcnt) {
+ if (opts->refcnt > 1) {
ret = -EBUSY;
goto end;
}
@@ -1158,13 +1163,21 @@ static struct config_item_type midi_func_type = {
static void f_midi_free_inst(struct usb_function_instance *f)
{
struct f_midi_opts *opts;
+ bool free = false;
opts = container_of(f, struct f_midi_opts, func_inst);
- if (opts->id_allocated)
- kfree(opts->id);
+ mutex_lock(&opts->lock);
+ if (!--opts->refcnt) {
+ free = true;
+ }
+ mutex_unlock(&opts->lock);
- kfree(opts);
+ if (free) {
+ if (opts->id_allocated)
+ kfree(opts->id);
+ kfree(opts);
+ }
}
static struct usb_function_instance *f_midi_alloc_inst(void)
@@ -1183,6 +1196,7 @@ static struct usb_function_instance *f_midi_alloc_inst(void)
opts->qlen = 32;
opts->in_ports = 1;
opts->out_ports = 1;
+ opts->refcnt = 1;
config_group_init_type_name(&opts->func_inst.group, "",
&midi_func_type);
@@ -1194,15 +1208,26 @@ static void f_midi_free(struct usb_function *f)
{
struct f_midi *midi;
struct f_midi_opts *opts;
+ bool free = false;
midi = func_to_midi(f);
opts = container_of(f->fi, struct f_midi_opts, func_inst);
- kfree(midi->id);
mutex_lock(&opts->lock);
- kfifo_free(&midi->in_req_fifo);
- kfree(midi);
- --opts->refcnt;
+ if (!--midi->free_ref) {
+ kfree(midi->id);
+ kfifo_free(&midi->in_req_fifo);
+ kfree(midi);
+ free = true;
+ }
mutex_unlock(&opts->lock);
+
+ if (free)
+ f_midi_free_inst(&opts->func_inst);
+}
+
+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)
@@ -1219,7 +1244,7 @@ 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);
}
@@ -1263,6 +1288,7 @@ 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)
--
2.14.1.342.g6490525c54-goog
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