On 5/18/19 12:54 PM, Ranjani Sridharan wrote:

On Fri, 2019-05-17 at 08:22 -0500, Pierre-Louis Bossart wrote:

...

On 5/17/19 1:08 AM, Kuninori Morimoto wrote:

...

From: Kuninori Morimoto kuninori.morimoto.gx@renesas.com

soc_pcm_components_open() try to call try_module_get() based on component->driver->module_get_upon_open. But, it should be always called, not relatead to .open callback. It should be called at (A) istead of (B)

=> (A) if (!component->driver->ops || !component->driver->ops->open) continue; => (B) if (component->driver->module_get_upon_open && !try_module_get(component->dev->driver->owner)) { ... }

ret = component->driver->ops->open(substream);

Signed-off-by: Kuninori Morimoto kuninori.morimoto.gx@renesas.com

Mark, Pierre-Louis, Vinod, Liam

I think this patch is correct, but I'm not sure. I'm happy if someone can confirm it.

The try_module_get()/module_put() mechanism is based on the assumption that the .open and .close callbacks are both mandatory.

Hi Pierre, But is this enforced? We could end up doing a try_module_get() without checking if there is a close callback in which case we'd never do the module_put(), isnt it?

My initial feedback was that changing the open case only wouldn't work.

We need to enforce that both the open/close callbacks are required and leave the code as is, or we apply both of Morimoto-san's patches (which unfortunately have the same subject to cover the two cases) and both open and close are optional - though I am having a hard time figuring out case where we we'd use one and the other.

Thanks, Ranjani

...

open flow: if (!component->driver->ops || !component->driver->ops->open) continue;

if (component->driver->module_get_upon_open &&
    !try_module_get(component->dev->driver->owner)) {
	ret = -ENODEV;
	goto module_err;
}

ret = component->driver->ops->open(substream);

close flow: if (!component->driver->ops || !component->driver->ops->close) continue;

component->driver->ops->close(substream);

if (component->driver->module_get_upon_open)
	module_put(component->dev->driver->owner);

it'd be odd to allow the refcount to be increased when there is no .open, since if there is no .close either then the refcount never decreases.

...

sound/soc/soc-pcm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c index 7737e00..7b4cda6 100644 --- a/sound/soc/soc-pcm.c +++ b/sound/soc/soc-pcm.c @@ -440,10 +440,6 @@ static int soc_pcm_components_open(struct snd_pcm_substream *substream, component = rtdcom->component; *last = component;

• if (!component->driver->ops ||
  

•     !component->driver->ops->open)
  

• 	continue;
  

• if (component->driver->module_get_upon_open &&
      !try_module_get(component->dev->driver->owner)) {
  	dev_err(component->dev,
  

@@ -452,6 +448,10 @@ static int soc_pcm_components_open(struct snd_pcm_substream *substream, return -ENODEV; }

• if (!component->driver->ops ||
  

•     !component->driver->ops->open)
  

• 	continue;
  

• ret = component->driver->ops->open(substream);
  if (ret < 0) {
  	dev_err(component->dev,
  
  

---

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