From: Takashi Iwai <tiwai@suse.de>
Date: Tue, 10 Jun 2025 06:43:19 +0000 (+0200)
Subject: ALSA: sb: Don't allow changing the DMA mode during operations
X-Git-Tag: v5.15.187~34
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=73337c003f3d1a8ffdd3010eb358e4fcd1bf271c;p=thirdparty%2Fkernel%2Fstable.git

ALSA: sb: Don't allow changing the DMA mode during operations

[ Upstream commit ed29e073ba93f2d52832804cabdd831d5d357d33 ]

When a PCM stream is already running, one shouldn't change the DMA
mode via kcontrol, which may screw up the hardware.  Return -EBUSY
instead.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=218185
Link: https://patch.msgid.link/20250610064322.26787-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/sound/isa/sb/sb16_main.c b/sound/isa/sb/sb16_main.c
index a9b87e159b2d1..5efbd0a41312b 100644
--- a/sound/isa/sb/sb16_main.c
+++ b/sound/isa/sb/sb16_main.c
@@ -703,6 +703,9 @@ static int snd_sb16_dma_control_put(struct snd_kcontrol *kcontrol, struct snd_ct
 	unsigned char nval, oval;
 	int change;
 	
+	if (chip->mode & (SB_MODE_PLAYBACK | SB_MODE_CAPTURE))
+		return -EBUSY;
+
 	nval = ucontrol->value.enumerated.item[0];
 	if (nval > 2)
 		return -EINVAL;