media: dvb_frontend: split dvb_frontend_handle_ioctl function

Over time, dvb_frontend_handle_ioctl() has grown to the point where
we now get a warning from the compiler about excessive stack usage:

drivers/media/dvb-core/dvb_frontend.c: In function 'dvb_frontend_handle_ioctl':
drivers/media/dvb-core/dvb_frontend.c:2692:1: error: the frame size of 1048 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Almost all of this is used by the dtv_frontend_properties structure
in the FE_GET_PROPERTY and FE_GET_FRONTEND commands. Splitting those
into separate function reduces the stack usage of the main function
to just 136 bytes, the others are under 500 each.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 6351a97f3d1877c8ccf378c4fefb4aeabc520e5a..209186c5cd9b920efe79534290d6be00100436f4 100644 (file)
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -2311,6 +2311,78 @@ static int dtv_set_frontend(struct dvb_frontend *fe)
        return 0;
 }
 
+static int dvb_get_property(struct dvb_frontend *fe, struct file *file,
+                           struct dtv_properties *tvps)
+{
+       struct dvb_frontend_private *fepriv = fe->frontend_priv;
+       struct dtv_property *tvp = NULL;
+       struct dtv_frontend_properties getp;
+       int i, err;
+
+       memcpy(&getp, &fe->dtv_property_cache, sizeof(getp));
+
+       dev_dbg(fe->dvb->device, "%s: properties.num = %d\n",
+               __func__, tvps->num);
+       dev_dbg(fe->dvb->device, "%s: properties.props = %p\n",
+               __func__, tvps->props);
+
+       /*
+        * Put an arbitrary limit on the number of messages that can
+        * be sent at once
+        */
+       if (!tvps->num || tvps->num > DTV_IOCTL_MAX_MSGS)
+               return -EINVAL;
+
+       tvp = memdup_user((void __user *)tvps->props, tvps->num * sizeof(*tvp));
+       if (IS_ERR(tvp))
+               return PTR_ERR(tvp);
+
+       /*
+        * Let's use our own copy of property cache, in order to
+        * avoid mangling with DTV zigzag logic, as drivers might
+        * return crap, if they don't check if the data is available
+        * before updating the properties cache.
+        */
+       if (fepriv->state != FESTATE_IDLE) {
+               err = dtv_get_frontend(fe, &getp, NULL);
+               if (err < 0)
+                       goto out;
+       }
+       for (i = 0; i < tvps->num; i++) {
+               err = dtv_property_process_get(fe, &getp,
+                                              tvp + i, file);
+               if (err < 0)
+                       goto out;
+       }
+
+       if (copy_to_user((void __user *)tvps->props, tvp,
+                        tvps->num * sizeof(struct dtv_property))) {
+               err = -EFAULT;
+               goto out;
+       }
+
+       err = 0;
+out:
+       kfree(tvp);
+       return err;
+}
+
+static int dvb_get_frontend(struct dvb_frontend *fe,
+                           struct dvb_frontend_parameters *p_out)
+{
+       struct dtv_frontend_properties getp;
+
+       /*
+        * Let's use our own copy of property cache, in order to
+        * avoid mangling with DTV zigzag logic, as drivers might
+        * return crap, if they don't check if the data is available
+        * before updating the properties cache.
+        */
+       memcpy(&getp, &fe->dtv_property_cache, sizeof(getp));
+
+       return dtv_get_frontend(fe, &getp, p_out);
+}
+
 static int dvb_frontend_handle_ioctl(struct file *file,
                                     unsigned int cmd, void *parg)
 {
@@ -2356,58 +2428,9 @@ static int dvb_frontend_handle_ioctl(struct file *file,
                err = 0;
                break;
        }
-       case FE_GET_PROPERTY: {
-               struct dtv_properties *tvps = parg;
-               struct dtv_property *tvp = NULL;
-               struct dtv_frontend_properties getp = fe->dtv_property_cache;
-
-               dev_dbg(fe->dvb->device, "%s: properties.num = %d\n",
-                       __func__, tvps->num);
-               dev_dbg(fe->dvb->device, "%s: properties.props = %p\n",
-                       __func__, tvps->props);
-
-               /*
-                * Put an arbitrary limit on the number of messages that can
-                * be sent at once
-                */
-               if (!tvps->num || (tvps->num > DTV_IOCTL_MAX_MSGS))
-                       return -EINVAL;
-
-               tvp = memdup_user((void __user *)tvps->props, tvps->num * sizeof(*tvp));
-               if (IS_ERR(tvp))
-                       return PTR_ERR(tvp);
-
-               /*
-                * Let's use our own copy of property cache, in order to
-                * avoid mangling with DTV zigzag logic, as drivers might
-                * return crap, if they don't check if the data is available
-                * before updating the properties cache.
-                */
-               if (fepriv->state != FESTATE_IDLE) {
-                       err = dtv_get_frontend(fe, &getp, NULL);
-                       if (err < 0) {
-                               kfree(tvp);
-                               return err;
-                       }
-               }
-               for (i = 0; i < tvps->num; i++) {
-                       err = dtv_property_process_get(fe, &getp,
-                                                      tvp + i, file);
-                       if (err < 0) {
-                               kfree(tvp);
-                               return err;
-                       }
-               }
-
-               if (copy_to_user((void __user *)tvps->props, tvp,
-                                tvps->num * sizeof(struct dtv_property))) {
-                       kfree(tvp);
-                       return -EFAULT;
-               }
-               kfree(tvp);
-               err = 0;
+       case FE_GET_PROPERTY:
+               err = dvb_get_property(fe, file, parg);
                break;
-       }
 
        case FE_GET_INFO: {
                struct dvb_frontend_info *info = parg;
@@ -2545,7 +2568,6 @@ static int dvb_frontend_handle_ioctl(struct file *file,
                fepriv->tune_mode_flags = (unsigned long)parg;
                err = 0;
                break;
-
        /* DEPRECATED dish control ioctls */
 
        case FE_DISHNETWORK_SEND_LEGACY_CMD:
@@ -2664,22 +2686,14 @@ static int dvb_frontend_handle_ioctl(struct file *file,
                        break;
                err = dtv_set_frontend(fe);
                break;
+
        case FE_GET_EVENT:
                err = dvb_frontend_get_event(fe, parg, file->f_flags);
                break;
 
-       case FE_GET_FRONTEND: {
-               struct dtv_frontend_properties getp = fe->dtv_property_cache;
-
-               /*
-                * Let's use our own copy of property cache, in order to
-                * avoid mangling with DTV zigzag logic, as drivers might
-                * return crap, if they don't check if the data is available
-                * before updating the properties cache.
-                */
-               err = dtv_get_frontend(fe, &getp, parg);
+       case FE_GET_FRONTEND:
+               err = dvb_get_frontend(fe, parg);
                break;
-       }
 
        default:
                return -ENOTSUPP;