On Wed, 17 Nov 2021 20:56:14 +0100,
Alex Elder wrote:
On 11/16/21 1:20 AM, Takashi Iwai wrote:
snd_ctl_remove() has to be called with card->controls_rwsem held (when
called after the card instantiation). This patch adds the missing
rwsem calls around it.
I see the comment above snd_ctl_remove() that says you must hold
the write lock. And given that, this seems correct to me.
I understand why you want to take the lock just once, rather
than each time snd_ctl_remove() is called.
However I believe the acquisition and release of the lock
belongs inside gbaudio_remove_controls(), not in its caller.
If you disagree, can you please explain why?
In general if the function returns an error and has a loop inside,
taking a lock in the caller side avoids the forgotten unlock.
Takashi
Otherwise, will you please submit version two, taking the
lock inside gbaudio_remove_controls()?
Thanks.
-Alex
Fixes: 510e340efe0c ("staging: greybus: audio: Add helper APIs for dynamic audio modules")
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
drivers/staging/greybus/audio_helper.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/greybus/audio_helper.c b/drivers/staging/greybus/audio_helper.c
index 1ed4772d2771..843760675876 100644
--- a/drivers/staging/greybus/audio_helper.c
+++ b/drivers/staging/greybus/audio_helper.c
@@ -192,7 +192,11 @@ int gbaudio_remove_component_controls(struct snd_soc_component *component,
unsigned int num_controls)
{
struct snd_card *card = component->card->snd_card;
+ int err;
- return gbaudio_remove_controls(card, component->dev, controls,
- num_controls, component->name_prefix);
+ down_write(&card->controls_rwsem);
+ err = gbaudio_remove_controls(card, component->dev, controls,
+ num_controls, component->name_prefix);
+ up_write(&card->controls_rwsem);
+ return err;
}