[PATCH v4 0/5] Refactor media IOCTL handling, add variable length arguments

[PATCH v4 0/5] Refactor media IOCTL handling, add variable length arguments

[Sakari Ailus]

Hi folks,

This is the fourth version of the media IOCTL handling rework set. What's
changed since v3:

patch 1:

- Use BUILD_BUG_ON() and ARRAY_SIZE() to ensure the ioctl array and the
  equivalent compat array are always in sync. (This caused quite a few
  conflicts with the rest of the patches.)

patch 5:                                                                        

- Don't use unlikely().

- Fix commit message --- the patch was changed to use supported IOCTL sizes
  but the commit message was not updated.
                                                                                
---                                                                             
                                                                                
The patches themselves have been reworked so I don't detail the changes         
in this set. What's noteworthy however is that the set adds support for         
variable length IOCTL arguments.                                                
                                                                                
(The motivation for these patches is having found myself pondering whether      
to have nine or thirteen reserved fields for the request IOCTL. I decided       
to address the problem instead. If this is found workable on the media          
controller we could follow the same model on V4L2.)                             

-- 
Kind regards,
Sakari

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

[Sakari Ailus]

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

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

[Hans Verkuil]

On 08/11/2016 10:29 PM, Sakari Ailus wrote:
> 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>

Acked-by: Hans Verkuil <hans.verkuil@cisco.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);
> 

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

[Mauro Carvalho Chehab]

Em Thu, 11 Aug 2016 23:29:14 +0300
Sakari Ailus <sakari.ailus@linux.intel.com> escreveu:

> 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)


Hmm...

> +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);


Why do we need the above? The only ioctl that it is handled inside
the compat logic is MEDIA_IOC_ENUM_LINKS. all the others fall back
to the usual handler, and we don't intend to add any other new
special case, as we're now using a different logic to handle 32 bit
pointers passed to a 64 bit Kernel that it is compatible with both 32
and 64 bits.

So, we don't expect to have the V4L2 compat32 mess here, but, instead,
to keep this untouched as we add more ioctl's.

Regards,
Mauro

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

[Sakari Ailus]

Hi Mauro,

On Tue, Sep 06, 2016 at 06:56:17AM -0300, Mauro Carvalho Chehab wrote:
> Em Thu, 11 Aug 2016 23:29:14 +0300
> Sakari Ailus <sakari.ailus@linux.intel.com> escreveu:
> 
> > 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)
> 
> 
> Hmm...
> 
> > +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);
> 
> 
> Why do we need the above? The only ioctl that it is handled inside
> the compat logic is MEDIA_IOC_ENUM_LINKS. all the others fall back
> to the usual handler, and we don't intend to add any other new
> special case, as we're now using a different logic to handle 32 bit
> pointers passed to a 64 bit Kernel that it is compatible with both 32
> and 64 bits.
> 
> So, we don't expect to have the V4L2 compat32 mess here, but, instead,
> to keep this untouched as we add more ioctl's.

That's a fair point. If we won't require compat handling for more IOCTLs,
we'll be fine with less generic compat handling.

I'll resend the set.

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@iki.fi	XMPP: sailus@retiisi.org.uk

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

[Mauro Carvalho Chehab]

Em Tue, 13 Sep 2016 13:51:25 +0300
Sakari Ailus <sakari.ailus@iki.fi> escreveu:

> Hi Mauro,
> 
> On Tue, Sep 06, 2016 at 06:56:17AM -0300, Mauro Carvalho Chehab wrote:
> > Em Thu, 11 Aug 2016 23:29:14 +0300
> > Sakari Ailus <sakari.ailus@linux.intel.com> escreveu:
> >   

> > So, we don't expect to have the V4L2 compat32 mess here, but, instead,
> > to keep this untouched as we add more ioctl's.  
> 
> That's a fair point. If we won't require compat handling for more IOCTLs,
> we'll be fine with less generic compat handling.
> 
> I'll resend the set.

OK, thanks!

Regards,
Mauro

[PATCH v4 2/5] media: Unify IOCTL handler calling

[Sakari Ailus]

Each IOCTL handler can be listed in an array instead of using a large and
cumbersome switch. Do that.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/media-device.c | 80 ++++++++++++--------------------------------
 1 file changed, 22 insertions(+), 58 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index aedd64e..cc6c566 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -419,20 +419,24 @@ static long media_device_get_topology(struct media_device *mdev,
 	return 0;
 }
 
-#define MEDIA_IOC(__cmd) \
-	[_IOC_NR(MEDIA_IOC_##__cmd)] = { .cmd = MEDIA_IOC_##__cmd }
+#define MEDIA_IOC(__cmd, func)						\
+	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
+		.cmd = MEDIA_IOC_##__cmd,				\
+		.fn = (long (*)(struct media_device *, void __user *))func,    \
+	}
 
 /* the table is indexed by _IOC_NR(cmd) */
 struct media_ioctl_info {
 	unsigned int cmd;
+	long (*fn)(struct media_device *dev, void __user *arg);
 };
 
 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),
+	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
+	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
+	MEDIA_IOC(ENUM_LINKS, media_device_enum_links),
+	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
+	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
 };
 
 static inline long is_valid_ioctl(const struct media_ioctl_info *info,
@@ -448,42 +452,17 @@ static long __media_device_ioctl(
 {
 	struct media_devnode *devnode = media_devnode_data(filp);
 	struct media_device *dev = devnode->media_dev;
+	const struct media_ioctl_info *info;
 	long ret;
 
 	ret = is_valid_ioctl(info_array, cmd);
 	if (ret)
 		return ret;
 
+	info = &info_array[_IOC_NR(cmd)];
+
 	mutex_lock(&dev->graph_mutex);
-	switch (cmd) {
-	case MEDIA_IOC_DEVICE_INFO:
-		ret = media_device_get_info(dev,
-				(struct media_device_info __user *)arg);
-		break;
-
-	case MEDIA_IOC_ENUM_ENTITIES:
-		ret = media_device_enum_entities(dev,
-				(struct media_entity_desc __user *)arg);
-		break;
-
-	case MEDIA_IOC_ENUM_LINKS:
-		ret = media_device_enum_links(dev,
-				(struct media_links_enum __user *)arg);
-		break;
-
-	case MEDIA_IOC_SETUP_LINK:
-		ret = media_device_setup_link(dev,
-				(struct media_link_desc __user *)arg);
-		break;
-
-	case MEDIA_IOC_G_TOPOLOGY:
-		ret = media_device_get_topology(dev,
-				(struct media_v2_topology __user *)arg);
-		break;
-
-	default:
-		ret = -ENOIOCTLCMD;
-	}
+	ret = info->fn(dev, arg);
 	mutex_unlock(&dev->graph_mutex);
 
 	return ret;
@@ -527,20 +506,16 @@ 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),
+	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
+	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
+	MEDIA_IOC(ENUM_LINKS32, media_device_enum_links32),
+	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
+	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
 };
 
 static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
 				      unsigned long arg)
 {
-	struct media_devnode *devnode = media_devnode_data(filp);
-	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
@@ -548,19 +523,8 @@ static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
 	 */
 	BUILD_BUG_ON(ARRAY_SIZE(ioctl_info) != ARRAY_SIZE(compat_ioctl_info));
 
-	switch (cmd) {
-	case MEDIA_IOC_ENUM_LINKS32:
-		mutex_lock(&dev->graph_mutex);
-		ret = media_device_enum_links32(dev,
-				(struct media_links_enum32 __user *)arg);
-		mutex_unlock(&dev->graph_mutex);
-		break;
-
-	default:
-		return media_device_ioctl(filp, cmd, arg);
-	}
-
-	return ret;
+	return __media_device_ioctl(
+		filp, cmd, (void __user *)arg, compat_ioctl_info);
 }
 #endif /* CONFIG_COMPAT */
 
-- 
2.7.4

[PATCH v4 3/5] media: Refactor copying IOCTL arguments from and to user space

[Sakari Ailus]

Refactor copying the IOCTL argument structs from the user space and back,
in order to reduce code copied around and make the implementation more
robust.

As a result, the copying is done while not holding the graph mutex.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/media-device.c | 190 ++++++++++++++++++++-----------------------
 1 file changed, 90 insertions(+), 100 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index cc6c566..d1b47a4 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -59,27 +59,24 @@ static int media_device_close(struct file *filp)
 }
 
 static int media_device_get_info(struct media_device *dev,
-				 struct media_device_info __user *__info)
+				 struct media_device_info *info)
 {
-	struct media_device_info info;
-
-	memset(&info, 0, sizeof(info));
+	memset(info, 0, sizeof(*info));
 
 	if (dev->driver_name[0])
-		strlcpy(info.driver, dev->driver_name, sizeof(info.driver));
+		strlcpy(info->driver, dev->driver_name, sizeof(info->driver));
 	else
-		strlcpy(info.driver, dev->dev->driver->name, sizeof(info.driver));
+		strlcpy(info->driver, dev->dev->driver->name,
+			sizeof(info->driver));
 
-	strlcpy(info.model, dev->model, sizeof(info.model));
-	strlcpy(info.serial, dev->serial, sizeof(info.serial));
-	strlcpy(info.bus_info, dev->bus_info, sizeof(info.bus_info));
+	strlcpy(info->model, dev->model, sizeof(info->model));
+	strlcpy(info->serial, dev->serial, sizeof(info->serial));
+	strlcpy(info->bus_info, dev->bus_info, sizeof(info->bus_info));
 
-	info.media_version = MEDIA_API_VERSION;
-	info.hw_revision = dev->hw_revision;
-	info.driver_version = dev->driver_version;
+	info->media_version = MEDIA_API_VERSION;
+	info->hw_revision = dev->hw_revision;
+	info->driver_version = dev->driver_version;
 
-	if (copy_to_user(__info, &info, sizeof(*__info)))
-		return -EFAULT;
 	return 0;
 }
 
@@ -101,29 +98,25 @@ static struct media_entity *find_entity(struct media_device *mdev, u32 id)
 }
 
 static long media_device_enum_entities(struct media_device *mdev,
-				       struct media_entity_desc __user *uent)
+				       struct media_entity_desc *entd)
 {
 	struct media_entity *ent;
-	struct media_entity_desc u_ent;
-
-	memset(&u_ent, 0, sizeof(u_ent));
-	if (copy_from_user(&u_ent.id, &uent->id, sizeof(u_ent.id)))
-		return -EFAULT;
-
-	ent = find_entity(mdev, u_ent.id);
 
+	ent = find_entity(mdev, entd->id);
 	if (ent == NULL)
 		return -EINVAL;
 
-	u_ent.id = media_entity_id(ent);
+	memset(entd, 0, sizeof(*entd));
+
+	entd->id = media_entity_id(ent);
 	if (ent->name)
-		strlcpy(u_ent.name, ent->name, sizeof(u_ent.name));
-	u_ent.type = ent->function;
-	u_ent.revision = 0;		/* Unused */
-	u_ent.flags = ent->flags;
-	u_ent.group_id = 0;		/* Unused */
-	u_ent.pads = ent->num_pads;
-	u_ent.links = ent->num_links - ent->num_backlinks;
+		strlcpy(entd->name, ent->name, sizeof(entd->name));
+	entd->type = ent->function;
+	entd->revision = 0;		/* Unused */
+	entd->flags = ent->flags;
+	entd->group_id = 0;		/* Unused */
+	entd->pads = ent->num_pads;
+	entd->links = ent->num_links - ent->num_backlinks;
 
 	/*
 	 * Workaround for a bug at media-ctl <= v1.10 that makes it to
@@ -139,14 +132,13 @@ static long media_device_enum_entities(struct media_device *mdev,
 	if (ent->function < MEDIA_ENT_F_OLD_BASE ||
 	    ent->function > MEDIA_ENT_T_DEVNODE_UNKNOWN) {
 		if (is_media_entity_v4l2_subdev(ent))
-			u_ent.type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
+			entd->type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
 		else if (ent->function != MEDIA_ENT_F_IO_V4L)
-			u_ent.type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
+			entd->type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
 	}
 
-	memcpy(&u_ent.raw, &ent->info, sizeof(ent->info));
-	if (copy_to_user(uent, &u_ent, sizeof(u_ent)))
-		return -EFAULT;
+	memcpy(&entd->raw, &ent->info, sizeof(ent->info));
+
 	return 0;
 }
 
@@ -158,8 +150,8 @@ static void media_device_kpad_to_upad(const struct media_pad *kpad,
 	upad->flags = kpad->flags;
 }
 
-static long __media_device_enum_links(struct media_device *mdev,
-				      struct media_links_enum *links)
+static long media_device_enum_links(struct media_device *mdev,
+				    struct media_links_enum *links)
 {
 	struct media_entity *entity;
 
@@ -206,64 +198,35 @@ static long __media_device_enum_links(struct media_device *mdev,
 	return 0;
 }
 
-static long media_device_enum_links(struct media_device *mdev,
-				    struct media_links_enum __user *ulinks)
-{
-	struct media_links_enum links;
-	int rval;
-
-	if (copy_from_user(&links, ulinks, sizeof(links)))
-		return -EFAULT;
-
-	rval = __media_device_enum_links(mdev, &links);
-	if (rval < 0)
-		return rval;
-
-	if (copy_to_user(ulinks, &links, sizeof(*ulinks)))
-		return -EFAULT;
-
-	return 0;
-}
-
 static long media_device_setup_link(struct media_device *mdev,
-				    struct media_link_desc __user *_ulink)
+				    struct media_link_desc *linkd)
 {
 	struct media_link *link = NULL;
-	struct media_link_desc ulink;
 	struct media_entity *source;
 	struct media_entity *sink;
-	int ret;
-
-	if (copy_from_user(&ulink, _ulink, sizeof(ulink)))
-		return -EFAULT;
 
 	/* Find the source and sink entities and link.
 	 */
-	source = find_entity(mdev, ulink.source.entity);
-	sink = find_entity(mdev, ulink.sink.entity);
+	source = find_entity(mdev, linkd->source.entity);
+	sink = find_entity(mdev, linkd->sink.entity);
 
 	if (source == NULL || sink == NULL)
 		return -EINVAL;
 
-	if (ulink.source.index >= source->num_pads ||
-	    ulink.sink.index >= sink->num_pads)
+	if (linkd->source.index >= source->num_pads ||
+	    linkd->sink.index >= sink->num_pads)
 		return -EINVAL;
 
-	link = media_entity_find_link(&source->pads[ulink.source.index],
-				      &sink->pads[ulink.sink.index]);
+	link = media_entity_find_link(&source->pads[linkd->source.index],
+				      &sink->pads[linkd->sink.index]);
 	if (link == NULL)
 		return -EINVAL;
 
 	/* Setup the link on both entities. */
-	ret = __media_entity_setup_link(link, ulink.flags);
-
-	if (copy_to_user(_ulink, &ulink, sizeof(ulink)))
-		return -EFAULT;
-
-	return ret;
+	return __media_entity_setup_link(link, linkd->flags);
 }
 
-static long __media_device_get_topology(struct media_device *mdev,
+static long media_device_get_topology(struct media_device *mdev,
 				      struct media_v2_topology *topo)
 {
 	struct media_entity *entity;
@@ -400,35 +363,41 @@ static long __media_device_get_topology(struct media_device *mdev,
 	return ret;
 }
 
-static long media_device_get_topology(struct media_device *mdev,
-				      struct media_v2_topology __user *utopo)
+static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int cmd)
 {
-	struct media_v2_topology ktopo;
-	int ret;
-
-	if (copy_from_user(&ktopo, utopo, sizeof(ktopo)))
+	/* All media IOCTLs are _IOWR() */
+	if (copy_from_user(karg, uarg, _IOC_SIZE(cmd)))
 		return -EFAULT;
 
-	ret = __media_device_get_topology(mdev, &ktopo);
-	if (ret < 0)
-		return ret;
+	return 0;
+}
 
-	if (copy_to_user(utopo, &ktopo, sizeof(*utopo)))
+static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
+{
+	/* All media IOCTLs are _IOWR() */
+	if (copy_to_user(uarg, karg, _IOC_SIZE(cmd)))
 		return -EFAULT;
 
 	return 0;
 }
 
-#define MEDIA_IOC(__cmd, func)						\
-	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
-		.cmd = MEDIA_IOC_##__cmd,				\
-		.fn = (long (*)(struct media_device *, void __user *))func,    \
+#define MEDIA_IOC_ARG(__cmd, func, from_user, to_user)	\
+	[_IOC_NR(MEDIA_IOC_##__cmd)] = {		\
+		.cmd = MEDIA_IOC_##__cmd,		\
+		.fn = (long (*)(struct media_device *, void *))func,	\
+		.arg_from_user = from_user,		\
+		.arg_to_user = to_user,			\
 	}
 
+#define MEDIA_IOC(__cmd, func)						\
+	MEDIA_IOC_ARG(__cmd, func, copy_arg_from_user, copy_arg_to_user)
+
 /* the table is indexed by _IOC_NR(cmd) */
 struct media_ioctl_info {
 	unsigned int cmd;
-	long (*fn)(struct media_device *dev, void __user *arg);
+	long (*fn)(struct media_device *dev, void *arg);
+	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
+	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
 };
 
 static const struct media_ioctl_info ioctl_info[] = {
@@ -453,6 +422,7 @@ static long __media_device_ioctl(
 	struct media_devnode *devnode = media_devnode_data(filp);
 	struct media_device *dev = devnode->media_dev;
 	const struct media_ioctl_info *info;
+	char __karg[256], *karg = __karg;
 	long ret;
 
 	ret = is_valid_ioctl(info_array, cmd);
@@ -461,10 +431,29 @@ static long __media_device_ioctl(
 
 	info = &info_array[_IOC_NR(cmd)];
 
+	if (_IOC_SIZE(info->cmd) > sizeof(__karg)) {
+		karg = kmalloc(_IOC_SIZE(info->cmd), GFP_KERNEL);
+		if (!karg)
+			return -ENOMEM;
+	}
+
+	if (info->arg_from_user) {
+		ret = info->arg_from_user(karg, arg, cmd);
+		if (ret)
+			goto out_free;
+	}
+
 	mutex_lock(&dev->graph_mutex);
-	ret = info->fn(dev, arg);
+	ret = info->fn(dev, karg);
 	mutex_unlock(&dev->graph_mutex);
 
+	if (!ret && info->arg_to_user)
+		ret = info->arg_to_user(arg, karg, cmd);
+
+out_free:
+	if (karg != __karg)
+		kfree(karg);
+
 	return ret;
 }
 
@@ -484,23 +473,24 @@ struct media_links_enum32 {
 	__u32 reserved[4];
 };
 
-static long media_device_enum_links32(struct media_device *mdev,
-				      struct media_links_enum32 __user *ulinks)
+static long from_user_enum_links32(void *karg, void __user *uarg,
+				   unsigned int cmd)
 {
-	struct media_links_enum links;
+	struct media_links_enum *links = karg;
+	struct media_links_enum32 __user *ulinks = uarg;
 	compat_uptr_t pads_ptr, links_ptr;
 
-	memset(&links, 0, sizeof(links));
+	memset(links, 0, sizeof(*links));
 
-	if (get_user(links.entity, &ulinks->entity)
+	if (get_user(links->entity, &ulinks->entity)
 	    || get_user(pads_ptr, &ulinks->pads)
 	    || get_user(links_ptr, &ulinks->links))
 		return -EFAULT;
 
-	links.pads = compat_ptr(pads_ptr);
-	links.links = compat_ptr(links_ptr);
+	links->pads = compat_ptr(pads_ptr);
+	links->links = compat_ptr(links_ptr);
 
-	return __media_device_enum_links(mdev, &links);
+	return 0;
 }
 
 #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct media_links_enum32)
@@ -508,7 +498,7 @@ static long media_device_enum_links32(struct media_device *mdev,
 static const struct media_ioctl_info compat_ioctl_info[] = {
 	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
 	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
-	MEDIA_IOC(ENUM_LINKS32, media_device_enum_links32),
+	MEDIA_IOC_ARG(ENUM_LINKS32, media_device_enum_links, from_user_enum_links32, NULL),
 	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
 	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
 };
-- 
2.7.4

Re: [PATCH v4 3/5] media: Refactor copying IOCTL arguments from and to user space

[Laurent Pinchart]

Hi Sakari,

Thank you for the patch.

On Thursday 11 Aug 2016 23:29:16 Sakari Ailus wrote:
> Refactor copying the IOCTL argument structs from the user space and back,
> in order to reduce code copied around and make the implementation more
> robust.
> 
> As a result, the copying is done while not holding the graph mutex.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/media/media-device.c | 190 +++++++++++++++++----------------------
>  1 file changed, 90 insertions(+), 100 deletions(-)
> 
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index cc6c566..d1b47a4 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -59,27 +59,24 @@ static int media_device_close(struct file *filp)
>  }
> 
>  static int media_device_get_info(struct media_device *dev,
> -				 struct media_device_info __user *__info)
> +				 struct media_device_info *info)
>  {
> -	struct media_device_info info;
> -
> -	memset(&info, 0, sizeof(info));
> +	memset(info, 0, sizeof(*info));
> 
>  	if (dev->driver_name[0])
> -		strlcpy(info.driver, dev->driver_name, sizeof(info.driver));
> +		strlcpy(info->driver, dev->driver_name, sizeof(info->driver));
>  	else
> -		strlcpy(info.driver, dev->dev->driver->name, 
sizeof(info.driver));
> +		strlcpy(info->driver, dev->dev->driver->name,
> +			sizeof(info->driver));
> 
> -	strlcpy(info.model, dev->model, sizeof(info.model));
> -	strlcpy(info.serial, dev->serial, sizeof(info.serial));
> -	strlcpy(info.bus_info, dev->bus_info, sizeof(info.bus_info));
> +	strlcpy(info->model, dev->model, sizeof(info->model));
> +	strlcpy(info->serial, dev->serial, sizeof(info->serial));
> +	strlcpy(info->bus_info, dev->bus_info, sizeof(info->bus_info));
> 
> -	info.media_version = MEDIA_API_VERSION;
> -	info.hw_revision = dev->hw_revision;
> -	info.driver_version = dev->driver_version;
> +	info->media_version = MEDIA_API_VERSION;
> +	info->hw_revision = dev->hw_revision;
> +	info->driver_version = dev->driver_version;
> 
> -	if (copy_to_user(__info, &info, sizeof(*__info)))
> -		return -EFAULT;
>  	return 0;
>  }
> 
> @@ -101,29 +98,25 @@ static struct media_entity *find_entity(struct
> media_device *mdev, u32 id) }
> 
>  static long media_device_enum_entities(struct media_device *mdev,
> -				       struct media_entity_desc __user *uent)
> +				       struct media_entity_desc *entd)
>  {
>  	struct media_entity *ent;
> -	struct media_entity_desc u_ent;
> -
> -	memset(&u_ent, 0, sizeof(u_ent));
> -	if (copy_from_user(&u_ent.id, &uent->id, sizeof(u_ent.id)))
> -		return -EFAULT;
> -
> -	ent = find_entity(mdev, u_ent.id);
> 
> +	ent = find_entity(mdev, entd->id);
>  	if (ent == NULL)
>  		return -EINVAL;
> 
> -	u_ent.id = media_entity_id(ent);
> +	memset(entd, 0, sizeof(*entd));
> +
> +	entd->id = media_entity_id(ent);
>  	if (ent->name)
> -		strlcpy(u_ent.name, ent->name, sizeof(u_ent.name));
> -	u_ent.type = ent->function;
> -	u_ent.revision = 0;		/* Unused */
> -	u_ent.flags = ent->flags;
> -	u_ent.group_id = 0;		/* Unused */
> -	u_ent.pads = ent->num_pads;
> -	u_ent.links = ent->num_links - ent->num_backlinks;
> +		strlcpy(entd->name, ent->name, sizeof(entd->name));
> +	entd->type = ent->function;
> +	entd->revision = 0;		/* Unused */
> +	entd->flags = ent->flags;
> +	entd->group_id = 0;		/* Unused */
> +	entd->pads = ent->num_pads;
> +	entd->links = ent->num_links - ent->num_backlinks;
> 
>  	/*
>  	 * Workaround for a bug at media-ctl <= v1.10 that makes it to
> @@ -139,14 +132,13 @@ static long media_device_enum_entities(struct
> media_device *mdev, if (ent->function < MEDIA_ENT_F_OLD_BASE ||
>  	    ent->function > MEDIA_ENT_T_DEVNODE_UNKNOWN) {
>  		if (is_media_entity_v4l2_subdev(ent))
> -			u_ent.type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
> +			entd->type = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
>  		else if (ent->function != MEDIA_ENT_F_IO_V4L)
> -			u_ent.type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
> +			entd->type = MEDIA_ENT_T_DEVNODE_UNKNOWN;
>  	}
> 
> -	memcpy(&u_ent.raw, &ent->info, sizeof(ent->info));
> -	if (copy_to_user(uent, &u_ent, sizeof(u_ent)))
> -		return -EFAULT;
> +	memcpy(&entd->raw, &ent->info, sizeof(ent->info));
> +
>  	return 0;
>  }
> 
> @@ -158,8 +150,8 @@ static void media_device_kpad_to_upad(const struct
> media_pad *kpad, upad->flags = kpad->flags;
>  }
> 
> -static long __media_device_enum_links(struct media_device *mdev,
> -				      struct media_links_enum *links)
> +static long media_device_enum_links(struct media_device *mdev,
> +				    struct media_links_enum *links)
>  {
>  	struct media_entity *entity;
> 
> @@ -206,64 +198,35 @@ static long __media_device_enum_links(struct
> media_device *mdev, return 0;
>  }
> 
> -static long media_device_enum_links(struct media_device *mdev,
> -				    struct media_links_enum __user *ulinks)
> -{
> -	struct media_links_enum links;
> -	int rval;
> -
> -	if (copy_from_user(&links, ulinks, sizeof(links)))
> -		return -EFAULT;
> -
> -	rval = __media_device_enum_links(mdev, &links);
> -	if (rval < 0)
> -		return rval;
> -
> -	if (copy_to_user(ulinks, &links, sizeof(*ulinks)))
> -		return -EFAULT;
> -
> -	return 0;
> -}
> -
>  static long media_device_setup_link(struct media_device *mdev,
> -				    struct media_link_desc __user *_ulink)
> +				    struct media_link_desc *linkd)
>  {
>  	struct media_link *link = NULL;
> -	struct media_link_desc ulink;
>  	struct media_entity *source;
>  	struct media_entity *sink;
> -	int ret;
> -
> -	if (copy_from_user(&ulink, _ulink, sizeof(ulink)))
> -		return -EFAULT;
> 
>  	/* Find the source and sink entities and link.
>  	 */
> -	source = find_entity(mdev, ulink.source.entity);
> -	sink = find_entity(mdev, ulink.sink.entity);
> +	source = find_entity(mdev, linkd->source.entity);
> +	sink = find_entity(mdev, linkd->sink.entity);
> 
>  	if (source == NULL || sink == NULL)
>  		return -EINVAL;
> 
> -	if (ulink.source.index >= source->num_pads ||
> -	    ulink.sink.index >= sink->num_pads)
> +	if (linkd->source.index >= source->num_pads ||
> +	    linkd->sink.index >= sink->num_pads)
>  		return -EINVAL;
> 
> -	link = media_entity_find_link(&source->pads[ulink.source.index],
> -				      &sink->pads[ulink.sink.index]);
> +	link = media_entity_find_link(&source->pads[linkd->source.index],
> +				      &sink->pads[linkd->sink.index]);
>  	if (link == NULL)
>  		return -EINVAL;
> 
>  	/* Setup the link on both entities. */
> -	ret = __media_entity_setup_link(link, ulink.flags);
> -
> -	if (copy_to_user(_ulink, &ulink, sizeof(ulink)))
> -		return -EFAULT;
> -
> -	return ret;
> +	return __media_entity_setup_link(link, linkd->flags);
>  }
> 
> -static long __media_device_get_topology(struct media_device *mdev,
> +static long media_device_get_topology(struct media_device *mdev,
>  				      struct media_v2_topology *topo)
>  {
>  	struct media_entity *entity;
> @@ -400,35 +363,41 @@ static long __media_device_get_topology(struct
> media_device *mdev, return ret;
>  }
> 
> -static long media_device_get_topology(struct media_device *mdev,
> -				      struct media_v2_topology __user *utopo)
> +static long copy_arg_from_user(void *karg, void __user *uarg, unsigned int
> cmd) {
> -	struct media_v2_topology ktopo;
> -	int ret;
> -
> -	if (copy_from_user(&ktopo, utopo, sizeof(ktopo)))
> +	/* All media IOCTLs are _IOWR() */
> +	if (copy_from_user(karg, uarg, _IOC_SIZE(cmd)))
>  		return -EFAULT;
> 
> -	ret = __media_device_get_topology(mdev, &ktopo);
> -	if (ret < 0)
> -		return ret;
> +	return 0;
> +}
> 
> -	if (copy_to_user(utopo, &ktopo, sizeof(*utopo)))
> +static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int
> cmd) +{
> +	/* All media IOCTLs are _IOWR() */
> +	if (copy_to_user(uarg, karg, _IOC_SIZE(cmd)))
>  		return -EFAULT;
> 
>  	return 0;
>  }
> 
> -#define MEDIA_IOC(__cmd, func)						
\
> -	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
> -		.cmd = MEDIA_IOC_##__cmd,				\
> -		.fn = (long (*)(struct media_device *, void __user *))func,    
\
> +#define MEDIA_IOC_ARG(__cmd, func, from_user, to_user)	\
> +	[_IOC_NR(MEDIA_IOC_##__cmd)] = {		\
> +		.cmd = MEDIA_IOC_##__cmd,		\
> +		.fn = (long (*)(struct media_device *, void *))func,	\
> +		.arg_from_user = from_user,		\
> +		.arg_to_user = to_user,			\
>  	}
> 
> +#define MEDIA_IOC(__cmd, func)						
\
> +	MEDIA_IOC_ARG(__cmd, func, copy_arg_from_user, copy_arg_to_user)
> +
>  /* the table is indexed by _IOC_NR(cmd) */
>  struct media_ioctl_info {
>  	unsigned int cmd;
> -	long (*fn)(struct media_device *dev, void __user *arg);
> +	long (*fn)(struct media_device *dev, void *arg);
> +	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int 
cmd);
> +	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
>  };
> 
>  static const struct media_ioctl_info ioctl_info[] = {
> @@ -453,6 +422,7 @@ static long __media_device_ioctl(
>  	struct media_devnode *devnode = media_devnode_data(filp);
>  	struct media_device *dev = devnode->media_dev;
>  	const struct media_ioctl_info *info;
> +	char __karg[256], *karg = __karg;
>  	long ret;
> 
>  	ret = is_valid_ioctl(info_array, cmd);
> @@ -461,10 +431,29 @@ static long __media_device_ioctl(
> 
>  	info = &info_array[_IOC_NR(cmd)];
> 
> +	if (_IOC_SIZE(info->cmd) > sizeof(__karg)) {
> +		karg = kmalloc(_IOC_SIZE(info->cmd), GFP_KERNEL);
> +		if (!karg)
> +			return -ENOMEM;
> +	}
> +
> +	if (info->arg_from_user) {
> +		ret = info->arg_from_user(karg, arg, cmd);
> +		if (ret)
> +			goto out_free;
> +	}
> +
>  	mutex_lock(&dev->graph_mutex);
> -	ret = info->fn(dev, arg);
> +	ret = info->fn(dev, karg);
>  	mutex_unlock(&dev->graph_mutex);
> 
> +	if (!ret && info->arg_to_user)
> +		ret = info->arg_to_user(arg, karg, cmd);
> +
> +out_free:
> +	if (karg != __karg)
> +		kfree(karg);
> +
>  	return ret;
>  }
> 
> @@ -484,23 +473,24 @@ struct media_links_enum32 {
>  	__u32 reserved[4];
>  };
> 
> -static long media_device_enum_links32(struct media_device *mdev,
> -				      struct media_links_enum32 __user 
*ulinks)
> +static long from_user_enum_links32(void *karg, void __user *uarg,
> +				   unsigned int cmd)
>  {
> -	struct media_links_enum links;
> +	struct media_links_enum *links = karg;
> +	struct media_links_enum32 __user *ulinks = uarg;
>  	compat_uptr_t pads_ptr, links_ptr;
> 
> -	memset(&links, 0, sizeof(links));
> +	memset(links, 0, sizeof(*links));
> 
> -	if (get_user(links.entity, &ulinks->entity)
> +	if (get_user(links->entity, &ulinks->entity)
>  	    || get_user(pads_ptr, &ulinks->pads)
>  	    || get_user(links_ptr, &ulinks->links))
>  		return -EFAULT;
> 
> -	links.pads = compat_ptr(pads_ptr);
> -	links.links = compat_ptr(links_ptr);
> +	links->pads = compat_ptr(pads_ptr);
> +	links->links = compat_ptr(links_ptr);
> 
> -	return __media_device_enum_links(mdev, &links);
> +	return 0;
>  }
> 
>  #define MEDIA_IOC_ENUM_LINKS32		_IOWR('|', 0x02, struct 
media_links_enum32)
> @@ -508,7 +498,7 @@ static long media_device_enum_links32(struct
> media_device *mdev, static const struct media_ioctl_info
> compat_ioctl_info[] = {
>  	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
>  	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
> -	MEDIA_IOC(ENUM_LINKS32, media_device_enum_links32),
> +	MEDIA_IOC_ARG(ENUM_LINKS32, media_device_enum_links,
> from_user_enum_links32, NULL),
> 	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
>  	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
>  };

-- 
Regards,

Laurent Pinchart

[PATCH v4 4/5] media: Add flags to tell whether to take graph mutex for an IOCTL

[Sakari Ailus]

New IOCTLs (especially for the request API) do not necessarily need the
graph mutex acquired. Leave this up to the drivers.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/media-device.c | 47 ++++++++++++++++++++++++++------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index d1b47a4..6f565a2 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -381,31 +381,36 @@ static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
 	return 0;
 }
 
-#define MEDIA_IOC_ARG(__cmd, func, from_user, to_user)	\
-	[_IOC_NR(MEDIA_IOC_##__cmd)] = {		\
-		.cmd = MEDIA_IOC_##__cmd,		\
+/* Do acquire the graph mutex */
+#define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
+
+#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
+	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
+		.cmd = MEDIA_IOC_##__cmd,				\
 		.fn = (long (*)(struct media_device *, void *))func,	\
-		.arg_from_user = from_user,		\
-		.arg_to_user = to_user,			\
+		.flags = fl,						\
+		.arg_from_user = from_user,				\
+		.arg_to_user = to_user,					\
 	}
 
-#define MEDIA_IOC(__cmd, func)						\
-	MEDIA_IOC_ARG(__cmd, func, copy_arg_from_user, copy_arg_to_user)
+#define MEDIA_IOC(__cmd, func, fl)					\
+	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)
 
 /* the table is indexed by _IOC_NR(cmd) */
 struct media_ioctl_info {
 	unsigned int cmd;
+	unsigned short flags;
 	long (*fn)(struct media_device *dev, void *arg);
 	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
 	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
 };
 
 static const struct media_ioctl_info ioctl_info[] = {
-	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
-	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
-	MEDIA_IOC(ENUM_LINKS, media_device_enum_links),
-	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
-	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
+	MEDIA_IOC(DEVICE_INFO, media_device_get_info, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(ENUM_LINKS, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
 };
 
 static inline long is_valid_ioctl(const struct media_ioctl_info *info,
@@ -443,9 +448,13 @@ static long __media_device_ioctl(
 			goto out_free;
 	}
 
-	mutex_lock(&dev->graph_mutex);
+	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
+		mutex_lock(&dev->graph_mutex);
+
 	ret = info->fn(dev, karg);
-	mutex_unlock(&dev->graph_mutex);
+
+	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
+		mutex_unlock(&dev->graph_mutex);
 
 	if (!ret && info->arg_to_user)
 		ret = info->arg_to_user(arg, karg, cmd);
@@ -496,11 +505,11 @@ static long from_user_enum_links32(void *karg, void __user *uarg,
 #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_device_get_info),
-	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
-	MEDIA_IOC_ARG(ENUM_LINKS32, media_device_enum_links, from_user_enum_links32, NULL),
-	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
-	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
+	MEDIA_IOC(DEVICE_INFO, media_device_get_info, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC_ARG(ENUM_LINKS32, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX, from_user_enum_links32, NULL),
+	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
 };
 
 static long media_device_compat_ioctl(struct file *filp, unsigned int cmd,
-- 
2.7.4

[PATCH v4 5/5] media: Support variable size IOCTL arguments

[Sakari Ailus]

Maintain a list of supported IOCTL argument sizes and allow only those in
the list.

As an additional bonus, IOCTL handlers will be able to check whether the
caller actually set (using the argument size) the field vs. assigning it
to zero. Separate macro can be provided for that.

This will be easier for applications as well since there is no longer the
problem of setting the reserved fields zero, or at least it is a lesser
problem.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 drivers/media/media-device.c | 56 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 51 insertions(+), 5 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 6f565a2..aa37520 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -384,22 +384,36 @@ static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
 /* Do acquire the graph mutex */
 #define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
 
-#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
+#define MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz, from_user, to_user)	\
 	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
 		.cmd = MEDIA_IOC_##__cmd,				\
 		.fn = (long (*)(struct media_device *, void *))func,	\
 		.flags = fl,						\
+		.alt_arg_sizes = alt_sz,				\
 		.arg_from_user = from_user,				\
 		.arg_to_user = to_user,					\
 	}
 
-#define MEDIA_IOC(__cmd, func, fl)					\
-	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)
+#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
+	MEDIA_IOC_SZ_ARG(__cmd, func, fl, NULL, from_user, to_user)
+
+#define MEDIA_IOC_SZ(__cmd, func, fl, alt_sz)			\
+	MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz,		\
+			 copy_arg_from_user, copy_arg_to_user)
+
+#define MEDIA_IOC(__cmd, func, fl)				\
+	MEDIA_IOC_ARG(__cmd, func, fl,				\
+		      copy_arg_from_user, copy_arg_to_user)
 
 /* the table is indexed by _IOC_NR(cmd) */
 struct media_ioctl_info {
 	unsigned int cmd;
 	unsigned short flags;
+	/*
+	 * Sizes of the alternative arguments. If there are none, this
+	 * pointer is NULL.
+	 */
+	const unsigned short *alt_arg_sizes;
 	long (*fn)(struct media_device *dev, void *arg);
 	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
 	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
@@ -413,11 +427,40 @@ static const struct media_ioctl_info ioctl_info[] = {
 	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
 };
 
+#define MASK_IOC_SIZE(cmd) \
+	((cmd) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
+
 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;
+	const unsigned short *alt_arg_sizes;
+
+	if (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info))
+		return -ENOIOCTLCMD;
+
+	info += _IOC_NR(cmd);
+
+	if (info->cmd == cmd)
+		return 0;
+
+	/*
+	 * Verify that the size-dependent patch of the IOCTL command
+	 * matches and that the size does not exceed the principal
+	 * argument size.
+	 */
+	if (MASK_IOC_SIZE(info->cmd) != MASK_IOC_SIZE(cmd)
+	    || _IOC_SIZE(info->cmd) < _IOC_SIZE(cmd))
+		return -ENOIOCTLCMD;
+
+	alt_arg_sizes = info->alt_arg_sizes;
+	if (!alt_arg_sizes)
+		return -ENOIOCTLCMD;
+
+	for (; *alt_arg_sizes; alt_arg_sizes++)
+		if (_IOC_SIZE(cmd) == *alt_arg_sizes)
+			return 0;
+
+	return -ENOIOCTLCMD;
 }
 
 static long __media_device_ioctl(
@@ -448,6 +491,9 @@ static long __media_device_ioctl(
 			goto out_free;
 	}
 
+	/* Set the rest of the argument struct to zero */
+	memset(karg + _IOC_SIZE(cmd), 0, _IOC_SIZE(info->cmd) - _IOC_SIZE(cmd));
+
 	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
 		mutex_lock(&dev->graph_mutex);
 
-- 
2.7.4

Re: [PATCH v4 5/5] media: Support variable size IOCTL arguments

[Hans Verkuil]

On 08/11/2016 10:29 PM, Sakari Ailus wrote:
> Maintain a list of supported IOCTL argument sizes and allow only those in
> the list.
> 
> As an additional bonus, IOCTL handlers will be able to check whether the
> caller actually set (using the argument size) the field vs. assigning it
> to zero. Separate macro can be provided for that.
> 
> This will be easier for applications as well since there is no longer the
> problem of setting the reserved fields zero, or at least it is a lesser
> problem.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

> ---
>  drivers/media/media-device.c | 56 ++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 51 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
> index 6f565a2..aa37520 100644
> --- a/drivers/media/media-device.c
> +++ b/drivers/media/media-device.c
> @@ -384,22 +384,36 @@ static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
>  /* Do acquire the graph mutex */
>  #define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
>  
> -#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
> +#define MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz, from_user, to_user)	\
>  	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
>  		.cmd = MEDIA_IOC_##__cmd,				\
>  		.fn = (long (*)(struct media_device *, void *))func,	\
>  		.flags = fl,						\
> +		.alt_arg_sizes = alt_sz,				\
>  		.arg_from_user = from_user,				\
>  		.arg_to_user = to_user,					\
>  	}
>  
> -#define MEDIA_IOC(__cmd, func, fl)					\
> -	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)
> +#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
> +	MEDIA_IOC_SZ_ARG(__cmd, func, fl, NULL, from_user, to_user)
> +
> +#define MEDIA_IOC_SZ(__cmd, func, fl, alt_sz)			\
> +	MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz,		\
> +			 copy_arg_from_user, copy_arg_to_user)
> +
> +#define MEDIA_IOC(__cmd, func, fl)				\
> +	MEDIA_IOC_ARG(__cmd, func, fl,				\
> +		      copy_arg_from_user, copy_arg_to_user)
>  
>  /* the table is indexed by _IOC_NR(cmd) */
>  struct media_ioctl_info {
>  	unsigned int cmd;
>  	unsigned short flags;
> +	/*
> +	 * Sizes of the alternative arguments. If there are none, this
> +	 * pointer is NULL.
> +	 */
> +	const unsigned short *alt_arg_sizes;
>  	long (*fn)(struct media_device *dev, void *arg);
>  	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
>  	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
> @@ -413,11 +427,40 @@ static const struct media_ioctl_info ioctl_info[] = {
>  	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
>  };
>  
> +#define MASK_IOC_SIZE(cmd) \
> +	((cmd) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
> +
>  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;
> +	const unsigned short *alt_arg_sizes;
> +
> +	if (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info))
> +		return -ENOIOCTLCMD;
> +
> +	info += _IOC_NR(cmd);
> +
> +	if (info->cmd == cmd)
> +		return 0;
> +
> +	/*
> +	 * Verify that the size-dependent patch of the IOCTL command
> +	 * matches and that the size does not exceed the principal
> +	 * argument size.
> +	 */
> +	if (MASK_IOC_SIZE(info->cmd) != MASK_IOC_SIZE(cmd)
> +	    || _IOC_SIZE(info->cmd) < _IOC_SIZE(cmd))
> +		return -ENOIOCTLCMD;
> +
> +	alt_arg_sizes = info->alt_arg_sizes;
> +	if (!alt_arg_sizes)
> +		return -ENOIOCTLCMD;
> +
> +	for (; *alt_arg_sizes; alt_arg_sizes++)
> +		if (_IOC_SIZE(cmd) == *alt_arg_sizes)
> +			return 0;
> +
> +	return -ENOIOCTLCMD;
>  }
>  
>  static long __media_device_ioctl(
> @@ -448,6 +491,9 @@ static long __media_device_ioctl(
>  			goto out_free;
>  	}
>  
> +	/* Set the rest of the argument struct to zero */
> +	memset(karg + _IOC_SIZE(cmd), 0, _IOC_SIZE(info->cmd) - _IOC_SIZE(cmd));
> +
>  	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
>  		mutex_lock(&dev->graph_mutex);
>  
> 

Re: [PATCH v4 5/5] media: Support variable size IOCTL arguments

[Hans Verkuil]

On 08/22/2016 02:55 PM, Hans Verkuil wrote:
> On 08/11/2016 10:29 PM, Sakari Ailus wrote:
>> Maintain a list of supported IOCTL argument sizes and allow only those in
>> the list.
>>
>> As an additional bonus, IOCTL handlers will be able to check whether the
>> caller actually set (using the argument size) the field vs. assigning it
>> to zero. Separate macro can be provided for that.
>>
>> This will be easier for applications as well since there is no longer the
>> problem of setting the reserved fields zero, or at least it is a lesser
>> problem.
>>
>> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> 
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

As discussed in v3, I will probably park this patch for now since we don't need
this functionality today.

Regards,

	Hans

> 
>> ---
>>  drivers/media/media-device.c | 56 ++++++++++++++++++++++++++++++++++++++++----
>>  1 file changed, 51 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
>> index 6f565a2..aa37520 100644
>> --- a/drivers/media/media-device.c
>> +++ b/drivers/media/media-device.c
>> @@ -384,22 +384,36 @@ static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
>>  /* Do acquire the graph mutex */
>>  #define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
>>  
>> -#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
>> +#define MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz, from_user, to_user)	\
>>  	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
>>  		.cmd = MEDIA_IOC_##__cmd,				\
>>  		.fn = (long (*)(struct media_device *, void *))func,	\
>>  		.flags = fl,						\
>> +		.alt_arg_sizes = alt_sz,				\
>>  		.arg_from_user = from_user,				\
>>  		.arg_to_user = to_user,					\
>>  	}
>>  
>> -#define MEDIA_IOC(__cmd, func, fl)					\
>> -	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)
>> +#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
>> +	MEDIA_IOC_SZ_ARG(__cmd, func, fl, NULL, from_user, to_user)
>> +
>> +#define MEDIA_IOC_SZ(__cmd, func, fl, alt_sz)			\
>> +	MEDIA_IOC_SZ_ARG(__cmd, func, fl, alt_sz,		\
>> +			 copy_arg_from_user, copy_arg_to_user)
>> +
>> +#define MEDIA_IOC(__cmd, func, fl)				\
>> +	MEDIA_IOC_ARG(__cmd, func, fl,				\
>> +		      copy_arg_from_user, copy_arg_to_user)
>>  
>>  /* the table is indexed by _IOC_NR(cmd) */
>>  struct media_ioctl_info {
>>  	unsigned int cmd;
>>  	unsigned short flags;
>> +	/*
>> +	 * Sizes of the alternative arguments. If there are none, this
>> +	 * pointer is NULL.
>> +	 */
>> +	const unsigned short *alt_arg_sizes;
>>  	long (*fn)(struct media_device *dev, void *arg);
>>  	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
>>  	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
>> @@ -413,11 +427,40 @@ static const struct media_ioctl_info ioctl_info[] = {
>>  	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
>>  };
>>  
>> +#define MASK_IOC_SIZE(cmd) \
>> +	((cmd) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
>> +
>>  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;
>> +	const unsigned short *alt_arg_sizes;
>> +
>> +	if (_IOC_NR(cmd) >= ARRAY_SIZE(ioctl_info))
>> +		return -ENOIOCTLCMD;
>> +
>> +	info += _IOC_NR(cmd);
>> +
>> +	if (info->cmd == cmd)
>> +		return 0;
>> +
>> +	/*
>> +	 * Verify that the size-dependent patch of the IOCTL command
>> +	 * matches and that the size does not exceed the principal
>> +	 * argument size.
>> +	 */
>> +	if (MASK_IOC_SIZE(info->cmd) != MASK_IOC_SIZE(cmd)
>> +	    || _IOC_SIZE(info->cmd) < _IOC_SIZE(cmd))
>> +		return -ENOIOCTLCMD;
>> +
>> +	alt_arg_sizes = info->alt_arg_sizes;
>> +	if (!alt_arg_sizes)
>> +		return -ENOIOCTLCMD;
>> +
>> +	for (; *alt_arg_sizes; alt_arg_sizes++)
>> +		if (_IOC_SIZE(cmd) == *alt_arg_sizes)
>> +			return 0;
>> +
>> +	return -ENOIOCTLCMD;
>>  }
>>  
>>  static long __media_device_ioctl(
>> @@ -448,6 +491,9 @@ static long __media_device_ioctl(
>>  			goto out_free;
>>  	}
>>  
>> +	/* Set the rest of the argument struct to zero */
>> +	memset(karg + _IOC_SIZE(cmd), 0, _IOC_SIZE(info->cmd) - _IOC_SIZE(cmd));
>> +
>>  	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
>>  		mutex_lock(&dev->graph_mutex);
>>  
>>
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