This is a note to let you know that I've just added the patch titled
ALSA: usb-audio: Fix the missing ctl name suffix at parsing SU
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: alsa-usb-audio-fix-the-missing-ctl-name-suffix-at-parsing-su.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 5a15f289ee87eaf33f13f08a4909ec99d837ec5f Mon Sep 17 00:00:00 2001
From: Takashi Iwai tiwai@suse.de Date: Mon, 18 Dec 2017 23:36:57 +0100 Subject: ALSA: usb-audio: Fix the missing ctl name suffix at parsing SU
From: Takashi Iwai tiwai@suse.de
commit 5a15f289ee87eaf33f13f08a4909ec99d837ec5f upstream.
The commit 89b89d121ffc ("ALSA: usb-audio: Add check return value for usb_string()") added the check of the return value from snd_usb_copy_string_desc(), which is correct per se, but it introduced a regression. In the original code, either the "Clock Source", "Playback Source" or "Capture Source" suffix is added after the terminal string, while the commit changed it to add the suffix only when get_term_name() is failing. It ended up with an incorrect ctl name like "PCM" instead of "PCM Capture Source".
Also, even the original code has a similar bug: when the ctl name is generated from snd_usb_copy_string_desc() for the given iSelector, it also doesn't put the suffix.
This patch addresses these issues: the suffix is added always when no static mapping is found. Also the patch tries to put more comments and cleans up the if/else block for better readability in order to avoid the same pitfall again.
Fixes: 89b89d121ffc ("ALSA: usb-audio: Add check return value for usb_string()") Reported-and-tested-by: Mauro Santos registo.mailling@gmail.com Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/usb/mixer.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-)
--- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -2101,20 +2101,25 @@ static int parse_audio_selector_unit(str kctl->private_value = (unsigned long)namelist; kctl->private_free = usb_mixer_selector_elem_free;
- nameid = uac_selector_unit_iSelector(desc); + /* check the static mapping table at first */ len = check_mapped_name(map, kctl->id.name, sizeof(kctl->id.name)); - if (len) - ; - else if (nameid) - len = snd_usb_copy_string_desc(state, nameid, kctl->id.name, - sizeof(kctl->id.name)); - 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)); + /* no mapping ? */ + /* if iSelector is given, use it */ + nameid = uac_selector_unit_iSelector(desc); + if (nameid) + len = snd_usb_copy_string_desc(state, nameid, + kctl->id.name, + sizeof(kctl->id.name)); + /* ... or pick up the terminal name at next */ + if (!len) + len = get_term_name(state, &state->oterm, + kctl->id.name, sizeof(kctl->id.name), 0); + /* ... or use the fixed string "USB" as the last resort */ + if (!len) + strlcpy(kctl->id.name, "USB", sizeof(kctl->id.name));
+ /* and add the proper suffix */ if (desc->bDescriptorSubtype == UAC2_CLOCK_SELECTOR) append_ctl_name(kctl, " Clock Source"); else if ((state->oterm.type & 0xff00) == 0x0100)
Patches currently in stable-queue which might be from tiwai@suse.de are
queue-4.4/alsa-usb-audio-fix-the-missing-ctl-name-suffix-at-parsing-su.patch queue-4.4/alsa-rawmidi-avoid-racy-info-ioctl-via-ctl-device.patch queue-4.4/acpi-apei-erst-fix-missing-error-handling-in-erst_reader.patch