[PATCH 3.16 050/254] ALSA: usb-audio: Add check return value for usb_string()

[Ben Hutchings]

3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jaejoong Kim <climbbb....@gmail.com>

commit 89b89d121ffcf8d9546633b98ded9d18b8f75891 upstream.

snd_usb_copy_string_desc() returns zero if usb_string() fails.
In case of failure, we need to check the snd_usb_copy_string_desc()'s
return value and add an exception case

Signed-off-by: Jaejoong Kim <climbbb....@gmail.com>
Signed-off-by: Takashi Iwai <ti...@suse.de>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 sound/usb/mixer.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2100,13 +2100,14 @@ static int parse_audio_selector_unit(str
        if (len)
                ;
        else if (nameid)
-               snd_usb_copy_string_desc(state, nameid, kctl->id.name,
+               len = snd_usb_copy_string_desc(state, nameid, kctl->id.name,
                                         sizeof(kctl->id.name));
-       else {
+       else
                len = get_term_name(state, &state->oterm,
                                    kctl->id.name, sizeof(kctl->id.name), 0);
-               if (!len)
-                       strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
+
+       if (!len) {
+               strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
 
                if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR)
                        append_ctl_name(kctl, " Clock Source");