linux-kernel - [PATCH] ALSA: hda/cs_dsp_ctl: Actually remove ALSA controls

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Message-ID: <20240503144920.61075-1-rf@opensource.cirrus.com>
Date: Fri, 3 May 2024 15:49:20 +0100
From: Richard Fitzgerald <rf@...nsource.cirrus.com>
To: <tiwai@...e.com>
CC: <linux-kernel@...r.kernel.org>, <patches@...nsource.cirrus.com>,
        <alsa-devel@...a-project.org>, <linux-sound@...r.kernel.org>
Subject: [PATCH] ALSA: hda/cs_dsp_ctl: Actually remove ALSA controls

hda_cs_dsp_control_remove() must remove the ALSA control when
deleting all the infrastructure for handling the control.

Without this it is possible for ALSA controls to be left in
the Soundcard after the amp driver module has been unloaded.
So the get/set callbacks point to code that no longer exists.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
Fixes: 3233b978af23 ("ALSA: hda: hda_cs_dsp_ctl: Add Library to support CS_DSP ALSA controls")
---
Note: it would be better to use the control private_free to do the
cleanup, and that is my plan long-term. But that is a larger change
to the code.

I like to keep bugfix patches as simple as possible so they are
low-risk and easy to cherry-pick into older kernels. So this patch
fixes the bug. Sometime I will send a patch for future kernel
versions that reworks the cleanup to use private_free.
---
 sound/pci/hda/hda_cs_dsp_ctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/pci/hda/hda_cs_dsp_ctl.c b/sound/pci/hda/hda_cs_dsp_ctl.c
index 463ca06036bf..a42653d3473d 100644
--- a/sound/pci/hda/hda_cs_dsp_ctl.c
+++ b/sound/pci/hda/hda_cs_dsp_ctl.c
@@ -203,6 +203,10 @@ void hda_cs_dsp_control_remove(struct cs_dsp_coeff_ctl *cs_ctl)
 {
 	struct hda_cs_dsp_coeff_ctl *ctl = cs_ctl->priv;
 
+	/* Only public firmware controls will have an associated kcontrol */
+	if (ctl && ctl->kctl)
+		snd_ctl_remove(ctl->card, ctl->kctl);
+
 	kfree(ctl);
 }
 EXPORT_SYMBOL_NS_GPL(hda_cs_dsp_control_remove, SND_HDA_CS_DSP_CONTROLS);
-- 
2.39.2