From f4794c6064a83d2c57b264bd299c367d172d1044 Mon Sep 17 00:00:00 2001
From: Hui Wang <hui.wang@canonical.com>
Date: Wed, 30 Sep 2020 13:51:46 +0800
Subject: [PATCH] ALSA: hda - Don't register a cb func if it is registered already
Git-commit: f4794c6064a83d2c57b264bd299c367d172d1044
Patch-mainline: v5.10-rc1
References: git-fixes

If the caller of enable_callback_mst() passes a cb func, the callee
function will malloc memory and link this cb func to the list
unconditionally. This will introduce problem if caller is in the
hda_codec_ops.init() since the init() will be repeatedly called in the
codec rt_resume().

So far, the patch_hdmi.c and patch_ca0132.c call enable_callback_mst()
in the hda_codec_ops.init().

Signed-off-by: Hui Wang <hui.wang@canonical.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200930055146.5665-1-hui.wang@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/pci/hda/hda_jack.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/sound/pci/hda/hda_jack.c
+++ b/sound/pci/hda/hda_jack.c
@@ -235,6 +235,18 @@ int snd_hda_jack_detect_state(struct hda
 }
 EXPORT_SYMBOL_GPL(snd_hda_jack_detect_state);
 
+static bool func_is_already_in_callback_list(struct hda_jack_tbl *jack,
+					     hda_jack_callback_fn func)
+{
+	struct hda_jack_callback *cb;
+
+	for (cb = jack->callback; cb; cb = cb->next) {
+		if (cb->func == func)
+			return true;
+	}
+	return false;
+}
+
 /**
  * snd_hda_jack_detect_enable - enable the jack-detection
  * @codec: the HDA codec
@@ -256,7 +268,7 @@ snd_hda_jack_detect_enable_callback(stru
 	jack = snd_hda_jack_tbl_new(codec, nid);
 	if (!jack)
 		return ERR_PTR(-ENOMEM);
-	if (func) {
+	if (func && !func_is_already_in_callback_list(jack, func)) {
 		callback = kzalloc(sizeof(*callback), GFP_KERNEL);
 		if (!callback)
 			return ERR_PTR(-ENOMEM);