[alsa-devel] [PATCH 2/2] ASoC: pcm: update module refcount if module_get_upon_open is set

[Ranjani Sridharan]

Setting the module_get_upon_open field for component driver
prevents the module refcount from being incremented during
component probe(). This could lead to the module being
allowed to be unloaded when a pcm stream is open. So,
if this field is set, the module's refcount should be
incremented during pcm open to prevent module removal
when the component is in use. And, the refcount should
be decremented upon pcm close.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
---
 sound/soc/soc-pcm.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 7fe5321000e8..d84a9a5b14c0 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -15,6 +15,7 @@
 #include <linux/delay.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <linux/export.h>
@@ -463,6 +464,9 @@ static int soc_pcm_components_close(struct snd_pcm_substream *substream,
 			continue;
 
 		component->driver->ops->close(substream);
+
+		if (component->driver->module_get_upon_open)
+			module_put(component->dev->driver->owner);
 	}
 
 	return 0;
@@ -513,6 +517,10 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
 		    !component->driver->ops->open)
 			continue;
 
+		if (component->driver->module_get_upon_open)
+			if (!try_module_get(component->dev->driver->owner))
+				return -ENODEV;
+
 		ret = component->driver->ops->open(substream);
 		if (ret < 0) {
 			dev_err(component->dev,
-- 
2.17.1