[QUEUED v20160420 16/19] intel_th: Hold output driver module reference while capture is active

[Alexander Shishkin]

Right now it's possible to unload the output subdevice's driver while
the capture to this output is active. Prevent this by holding the
output driver's module reference.

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Reviewed-by: Laurent Fert <laurent.fert@xxxxxxxxx>
---
 drivers/hwtracing/intel_th/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 20339470c2..1be543e8e4 100644
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -189,6 +189,9 @@ static int intel_th_output_activate(struct intel_th_device *thdev)
 	if (!thdrv)
 		return -ENODEV;
 
+	if (!try_module_get(thdrv->driver.owner))
+		return -ENODEV;
+
 	if (thdrv->activate)
 		return thdrv->activate(thdev);
 
@@ -209,6 +212,8 @@ static void intel_th_output_deactivate(struct intel_th_device *thdev)
 		thdrv->deactivate(thdev);
 	else
 		intel_th_trace_disable(thdev);
+
+	module_put(thdrv->driver.owner);
 }
 
 static ssize_t active_show(struct device *dev, struct device_attribute *attr,
-- 
2.8.0.rc3