V4L/DVB (6636): xc2028: protect device list

Protect refcount changes and modifications to xc2028_list with a mutex.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 13 insertions, 1 deletions

diff --git a/drivers/media/video/tuner-xc2028.c b/drivers/media/video/tuner-xc2028.c
index a01231a0410d..ac7f3e1d32f4 100644
--- a/drivers/media/video/tuner-xc2028.c
+++ b/drivers/media/video/tuner-xc2028.c
@@ -44,6 +44,8 @@ MODULE_PARM_DESC(audio_std,
         "NICAM/B\n");
 
 static LIST_HEAD(xc2028_list);
+static DEFINE_MUTEX(xc2028_list_mutex);
+
 /* struct for storing firmware table */
 struct firmware_description {
         unsigned int  type;
@@ -854,6 +856,8 @@ static int xc2028_dvb_release(struct dvb_frontend *fe)
 
         tuner_dbg("%s called\n", __FUNCTION__);
 
+        mutex_lock(&xc2028_list_mutex);
+
         priv->count--;
 
         if (!priv->count) {
@@ -865,6 +869,8 @@ static int xc2028_dvb_release(struct dvb_frontend *fe)
                 kfree(priv);
         }
 
+        mutex_unlock(&xc2028_list_mutex);
+
         return 0;
 }
 
@@ -940,6 +946,8 @@ void *xc2028_attach(struct dvb_frontend *fe, struct xc2028_config *cfg)
 
         video_dev = cfg->video_dev;
 
+        mutex_lock(&xc2028_list_mutex);
+
         list_for_each_entry(priv, &xc2028_list, xc2028_list) {
                 if (priv->video_dev == cfg->video_dev) {
                         video_dev = NULL;
@@ -949,8 +957,10 @@ void *xc2028_attach(struct dvb_frontend *fe, struct xc2028_config *cfg)
 
         if (video_dev) {
                 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-                if (priv == NULL)
+                if (priv == NULL) {
+                        mutex_unlock(&xc2028_list_mutex);
                         return NULL;
+                }
 
                 priv->bandwidth = BANDWIDTH_6_MHZ;
                 priv->need_load_generic = 1;
@@ -974,6 +984,8 @@ void *xc2028_attach(struct dvb_frontend *fe, struct xc2028_config *cfg)
 
         tuner_info("type set to %s\n", "XCeive xc2028/xc3028 tuner");
 
+        mutex_unlock(&xc2028_list_mutex);
+
         return fe;
 }