Hi Greg,
On 12/24/2022 12:59 AM, Greg KH wrote:
On Fri, Dec 23, 2022 at 03:31:56PM -0800, Wesley Cheng wrote:
Allow for checks on a specific USB audio device to see if a requested PCM format is supported. This is needed for support for when playback is initiated by the ASoC USB backend path.
Signed-off-by: Wesley Cheng quic_wcheng@quicinc.com
sound/usb/card.c | 19 +++++++++++++++++++ sound/usb/card.h | 3 +++ 2 files changed, 22 insertions(+)
diff --git a/sound/usb/card.c b/sound/usb/card.c index 396e5a34e23b..9b8d2ed308c8 100644 --- a/sound/usb/card.c +++ b/sound/usb/card.c @@ -133,6 +133,25 @@ int snd_usb_unregister_vendor_ops(void) } EXPORT_SYMBOL_GPL(snd_usb_unregister_vendor_ops);
+struct snd_usb_stream *snd_usb_find_suppported_substream(int card_idx,
struct snd_pcm_hw_params *params, int direction)+{
- struct snd_usb_stream *as;
- struct snd_usb_substream *subs = NULL;
- const struct audioformat *fmt;
- if (usb_chip[card_idx] && enable[card_idx]) {
list_for_each_entry(as, &usb_chip[card_idx]->pcm_list, list) {subs = &as->substream[direction];fmt = find_substream_format(subs, params);if (fmt)return as;}- }
Where is the locking here? How can you walk a list that can be changed as you walk it?
And what about reference counting? You are returning a pointer to a structure, who now "owns" it? What happens if it is removed from the system after you return it?
- return 0;
Didn't sparse complain about this? You can't return "0" as a pointer, it should be NULL.
Always run basic tools like sparse on code before submitting it so that we don't have to find errors like this.
Got it...I didn't get a chance to run that, but will do it on future submissions. Will also address the locking and pointer reference you mentioned.
Thanks Wesley Cheng