[alsa-devel] [PATCH 1/2] ASoC: Prevent components from being bound to multiple cards

[Lars-Peter Clausen]

A component can only be bound to a single card at a time. Binding it to
card while it is already bound to another will result in undefined
behavior.

As the undefined behavior might only manifest itself later on it is not
necessarily always straight forward to find the cause. To prevent this add
a check that refuses to bind a component to multiple cards as well as
prints a error describing the problem.

Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
---
 sound/soc/soc-core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 8baf87d..d9ae826 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1104,9 +1104,19 @@ static int soc_probe_component(struct snd_soc_card *card,
 	struct snd_soc_dai *dai;
 	int ret;
 
-	if (!strcmp(component->name, "snd-soc-dummy") || component->probed)
+	if (!strcmp(component->name, "snd-soc-dummy"))
 		return 0;
 
+	if (component->probed) {
+		if (component->card != card) {
+			dev_err(component->dev,
+				"Trying to bind component to card \"%s\" but is already bound to card \"%s\"\n",
+				card->name, component->card->name);
+			return -ENODEV;
+		}
+		return 0;
+	}
+
 	component->card = card;
 	dapm->card = card;
 	soc_set_name_prefix(card, component);
-- 
2.1.4