[PATCH 5.8 056/633] ALSA: hda - Fix the return value if cb func is already registered

[Greg Kroah-Hartman]

From: Hui Wang <hui.w...@canonical.com>

commit 033e4040d453f1f7111e5957a54f3019eb089cc6 upstream.

If the cb function is already registered, should return the pointer
of the structure hda_jack_callback which contains this cb func, but
instead it returns the NULL.

Now fix it by replacing func_is_already_in_callback_list() with
find_callback_from_list().

Fixes: f4794c6064a8 ("ALSA: hda - Don't register a cb func if it is registered 
already")
Reported-and-suggested-by: Dan Carpenter <dan.carpen...@oracle.com>
Cc: <sta...@vger.kernel.org>
Signed-off-by: Hui Wang <hui.w...@canonical.com>
Link: https://lore.kernel.org/r/20201022030221.22393-1-hui.w...@canonical.com
Signed-off-by: Takashi Iwai <ti...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 sound/pci/hda/hda_jack.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

--- a/sound/pci/hda/hda_jack.c
+++ b/sound/pci/hda/hda_jack.c
@@ -275,16 +275,21 @@ int snd_hda_jack_detect_state_mst(struct
 }
 EXPORT_SYMBOL_GPL(snd_hda_jack_detect_state_mst);
 
-static bool func_is_already_in_callback_list(struct hda_jack_tbl *jack,
-                                            hda_jack_callback_fn func)
+static struct hda_jack_callback *
+find_callback_from_list(struct hda_jack_tbl *jack,
+                       hda_jack_callback_fn func)
 {
        struct hda_jack_callback *cb;
 
+       if (!func)
+               return NULL;
+
        for (cb = jack->callback; cb; cb = cb->next) {
                if (cb->func == func)
-                       return true;
+                       return cb;
        }
-       return false;
+
+       return NULL;
 }
 
 /**
@@ -309,7 +314,10 @@ snd_hda_jack_detect_enable_callback_mst(
        jack = snd_hda_jack_tbl_new(codec, nid, dev_id);
        if (!jack)
                return ERR_PTR(-ENOMEM);
-       if (func && !func_is_already_in_callback_list(jack, func)) {
+
+       callback = find_callback_from_list(jack, func);
+
+       if (func && !callback) {
                callback = kzalloc(sizeof(*callback), GFP_KERNEL);
                if (!callback)
                        return ERR_PTR(-ENOMEM);