[PATCH v4 1/5] media: Determine early whether an IOCTL is supported

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Preparation for refactoring media IOCTL handling to unify common parts.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/media-device.c | 54 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 1795abe..aedd64e 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -419,13 +419,41 @@ static long media_device_get_topology(struct media_device *mdev,
 	return 0;
 }
 
-static long media_device_ioctl(struct file *filp, unsigned int cmd,
-			       unsigned long arg)
+#define MEDIA_IOC(__cmd) \
+	[_IOC_NR(MEDIA_IOC_##__cmd)] = { .cmd = MEDIA_IOC_##__cmd }
+
+/* the table is indexed by _IOC_NR(cmd) */
+struct media_ioctl_info {
+	unsigned int cmd;
+};
+
+static const struct media_ioctl_info ioctl_info[] = {
+	MEDIA_IOC(DEVICE_INFO),
+	MEDIA_IOC(ENUM_ENTITIES),
+	MEDIA_IOC(ENUM_LINKS),
+	MEDIA_IOC(SETUP_LINK),
+	MEDIA_IOC(G_TOPOLOGY),
+};
+
+static inline long is_valid_ioctl(const struct media_ioctl_info *info,
+				  unsigned int cmd)
+{
+	return (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info)
+		|| info[_IOC_NR(cmd)].cmd != cmd) ? -ENOIOCTLCMD : 0;
+}
+
+static long __media_device_ioctl(
+	struct file *filp, unsigned int cmd, void __user *arg,
+	const struct media_ioctl_info *info_array)
 {
 	struct media_devnode *devnode = media_devnode_data(filp);
 	struct media_device *dev = devnode->media_dev;
 	long ret;
 
+	ret = is_valid_ioctl(info_array, cmd);
+	if (ret)
+		return ret;
+
 	mutex_lock(&dev->graph_mutex);
 	switch (cmd) {
 	case MEDIA_IOC_DEVICE_INFO:
@@ -461,6 +489,13 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
 	return ret;
 }
 
+static long media_device_ioctl(struct file *filp, unsigned int cmd,
+			       unsigned long arg)
+{
+	return __media_device_ioctl(
+		filp, cmd, (void __user *)arg, ioctl_info);
+}
+
 #ifdef CONFIG_COMPAT
 
 struct media_links_enum32 {
@@ -491,6 +526,14 @@ static long media_device_enum_links32(struct media_device *mdev,
 
 #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)
 
+static const struct media_ioctl_info compat_ioctl_info[] = {
+	MEDIA_IOC(DEVICE_INFO),
+	MEDIA_IOC(ENUM_ENTITIES),
+	MEDIA_IOC(ENUM_LINKS32),
+	MEDIA_IOC(SETUP_LINK),
+	MEDIA_IOC(G_TOPOLOGY),
+};
+
 static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
 				      unsigned long arg)
 {
@@ -498,6 +541,13 @@ static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
 	struct media_device *dev = devnode->media_dev;
 	long ret;
 
+	/*
+	 * The number of supported IOCTLs is the same for both regular and
+	 * compat cases. Instead of passing the sizes around, ensure that
+	 * they match.
+	 */
+	BUILD_BUG_ON(ARRAY_SIZE(ioctl_info) != ARRAY_SIZE(compat_ioctl_info));
+
 	switch (cmd) {
 	case MEDIA_IOC_ENUM_LINKS32:
 		mutex_lock(&dev->graph_mutex);
-- 
2.7.4