Patch "ALSA: hda - Fix endless loop of codec configure" 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: hda - Fix endless loop of codec configure

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-hda-fix-endless-loop-of-codec-configure.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, 28 Jun 2017 12:02:02 +0200
Subject: ALSA: hda - Fix endless loop of codec configure

From: Takashi Iwai <[email protected]>

commit d94815f917da770d42c377786dc428f542e38f71 upstream.

azx_codec_configure() loops over the codecs found on the given controller via a linked list. The code used to work in the past, but in the current version, this may lead to an endless loop when a codec binding returns an error.

The culprit is that the snd_hda_codec_configure() unregisters the device upon error, and this eventually deletes the given codec object from the bus. Since the list is initialized via list_del_init(), the next object points to the same device itself. This behavior change was introduced at splitting the HD-audio code code, and forgotten to adapt it here.

For fixing this bug, just use a *_safe() version of list iteration.

---
 sound/pci/hda/hda_codec.h      |    2 ++
 sound/pci/hda/hda_controller.c |    8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

@@ -294,6 +294,8 @@ struct hda_codec {
 
 #define list_for_each_codec(c, bus) \
 	list_for_each_entry(c, &(bus)->core.codec_list, core.list)
+#define list_for_each_codec_safe(c, n, bus)				\
+	list_for_each_entry_safe(c, n, &(bus)->core.codec_list, core.list)
 
 /* snd_hda_codec_read/write optional flags */
 #define HDA_RW_NO_RESPONSE_FALLBACK	(1 << 0)

@@ -1337,8 +1337,12 @@ EXPORT_SYMBOL_GPL(azx_probe_codecs);
 /* configure each codec instance */
 int azx_codec_configure(struct azx *chip)
 {
-	struct hda_codec *codec;
-	list_for_each_codec(codec, &chip->bus) {
+	struct hda_codec *codec, *next;
+
+	/* use _safe version here since snd_hda_codec_configure() deregisters
+	 * the device upon error and deletes itself from the bus list.
+	 */
+	list_for_each_codec_safe(codec, next, &chip->bus) {
 		snd_hda_codec_configure(codec);
 	}
 	return 0;

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

queue-4.11/alsa-hda-fix-endless-loop-of-codec-configure.patch queue-4.11/alsa-hda-set-input_path-bitmap-to-zero-after-moving-it-to-new-place.patch