Patch "ALSA: pcm: Don't treat NULL chmap as a fatal error" has been added to the 4.11-stable tree

This is a note to let you know that I've just added the patch titled

ALSA: pcm: Don't treat NULL chmap as a fatal error

to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
alsa-pcm-don-t-treat-null-chmap-as-a-fatal-error.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Takashi Iwai <[email protected]>
Date: Wed, 14 Jun 2017 16:20:32 +0200
Subject: ALSA: pcm: Don't treat NULL chmap as a fatal error

From: Takashi Iwai <[email protected]>

commit 2deaeaf102d692cb6f764123b1df7aa118a8e97c upstream.

The standard PCM chmap helper callbacks treat the NULL info->chmap as a fatal error and spews the kernel warning with stack trace when CONFIG_SND_DEBUG is on. This was OK, originally it was supposed to be always static and non-NULL. But, as the recent addition of Intel LPE audio driver shows, the chmap content may vary dynamically, and it can be even NULL when disconnected. The user still sees the kernel warning unnecessarily.

For clearing such a confusion, this patch simply removes the snd_BUG_ON() in each place, just returns an error without warning.

---
 sound/core/pcm_lib.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -2492,7 +2492,7 @@ static int pcm_chmap_ctl_get(struct snd_
 	struct snd_pcm_substream *substream;
 	const struct snd_pcm_chmap_elem *map;
 
-	if (snd_BUG_ON(!info->chmap))
+	if (!info->chmap)
 		return -EINVAL;
 	substream = snd_pcm_chmap_substream(info, idx);
 	if (!substream)

@@ -2524,7 +2524,7 @@ static int pcm_chmap_ctl_tlv(struct snd_
 	unsigned int __user *dst;
 	int c, count = 0;
 
-	if (snd_BUG_ON(!info->chmap))
+	if (!info->chmap)
 		return -EINVAL;
 	if (size < 8)
 		return -ENOMEM;

Patches currently in stable-queue which might be from [email protected] are

queue-4.11/alsa-pcm-don-t-treat-null-chmap-as-a-fatal-error.patch queue-4.11/alsa-hda-apply-quirks-to-broxton-t-too.patch queue-4.11/alsa-firewire-lib-fix-stall-of-process-context-at-packet-error.patch queue-4.11/alsa-hda-add-coffelake-pci-id.patch