[PATCH v2 1/2] drm: vmwgfx: remove drm_driver::master_set() return typ

[PATCH v2 1/2] drm: vmwgfx: remove drm_driver::master_set() return typ

[Emil Velikov]

The function always returns zero (success). Ideally we'll remove it all
together - although that's requires a little more work.

For now, we can drop the return type and simplify the drm core code
surrounding it.

v2: remove redundant assignment (Sam)

Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
---
VMWare team, I'm planning to push this via drm-misc. Review, ack and
comments are appreciated.
---
 drivers/gpu/drm/drm_auth.c          | 32 +++++++----------------------
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.c |  8 +++-----
 include/drm/drm_drv.h               |  4 ++--
 3 files changed, 12 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 74ce0c29c960..4c723e3a689c 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -122,27 +122,19 @@ struct drm_master *drm_master_create(struct drm_device *dev)
 	return master;
 }
 
-static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
-			  bool new_master)
+static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
+			   bool new_master)
 {
-	int ret = 0;
-
 	dev->master = drm_master_get(fpriv->master);
-	if (dev->driver->master_set) {
-		ret = dev->driver->master_set(dev, fpriv, new_master);
-		if (unlikely(ret != 0)) {
-			drm_master_put(&dev->master);
-		}
-	}
+	if (dev->driver->master_set)
+		dev->driver->master_set(dev, fpriv, new_master);
 
-	fpriv->was_master = (ret == 0);
-	return ret;
+	fpriv->was_master = true;
 }
 
 static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 {
 	struct drm_master *old_master;
-	int ret;
 
 	lockdep_assert_held_once(&dev->master_mutex);
 
@@ -157,22 +149,12 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 	fpriv->is_master = 1;
 	fpriv->authenticated = 1;
 
-	ret = drm_set_master(dev, fpriv, true);
-	if (ret)
-		goto out_err;
+	drm_set_master(dev, fpriv, true);
 
 	if (old_master)
 		drm_master_put(&old_master);
 
 	return 0;
-
-out_err:
-	/* drop references and restore old master on failure */
-	drm_master_put(&fpriv->master);
-	fpriv->master = old_master;
-	fpriv->is_master = 0;
-
-	return ret;
 }
 
 /*
@@ -265,7 +247,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 		goto out_unlock;
 	}
 
-	ret = drm_set_master(dev, file_priv, false);
+	drm_set_master(dev, file_priv, false);
 out_unlock:
 	mutex_unlock(&dev->master_mutex);
 	return ret;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index c2247a893ed4..470428387878 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -1129,9 +1129,9 @@ static long vmw_compat_ioctl(struct file *filp, unsigned int cmd,
 }
 #endif
 
-static int vmw_master_set(struct drm_device *dev,
-			  struct drm_file *file_priv,
-			  bool from_open)
+static void vmw_master_set(struct drm_device *dev,
+			   struct drm_file *file_priv,
+			   bool from_open)
 {
 	/*
 	 * Inform a new master that the layout may have changed while
@@ -1139,8 +1139,6 @@ static int vmw_master_set(struct drm_device *dev,
 	 */
 	if (!from_open)
 		drm_sysfs_hotplug_event(dev);
-
-	return 0;
 }
 
 static void vmw_master_drop(struct drm_device *dev,
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index bb924cddc09c..835c38a76ef6 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -311,8 +311,8 @@ struct drm_driver {
 	 *
 	 * Called whenever the minor master is set. Only used by vmwgfx.
 	 */
-	int (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
-			  bool from_open);
+	void (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
+			   bool from_open);
 	/**
 	 * @master_drop:
 	 *
-- 
2.25.1

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[PATCH v2 2/2] drm/auth: make drm_{set,drop]master_ioctl symmetrical

[Emil Velikov]

Currently the ret handling is all over the place - with two redundant
assignments and another one addressed earlier.

Use the exact same flow in both functions.

v2: straighten the code flow, instead of just removing the assignments

Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
---
Colin, pretty sure that this should address couple of Coverity warnings.
Yet I didn't check their web UI thingy.
---
 drivers/gpu/drm/drm_auth.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 4c723e3a689c..f2d46b7ac6f9 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -215,7 +215,7 @@ drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 			struct drm_file *file_priv)
 {
-	int ret = 0;
+	int ret;
 
 	mutex_lock(&dev->master_mutex);
 
@@ -272,12 +272,15 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
 	if (ret)
 		goto out_unlock;
 
-	ret = -EINVAL;
-	if (!drm_is_current_master(file_priv))
+	if (!drm_is_current_master(file_priv)) {
+		ret = -EINVAL;
 		goto out_unlock;
+	}
 
-	if (!dev->master)
+	if (!dev->master) {
+		ret = -EINVAL;
 		goto out_unlock;
+	}
 
 	if (file_priv->master->lessor != NULL) {
 		DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
@@ -285,7 +288,6 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
 		goto out_unlock;
 	}
 
-	ret = 0;
 	drm_drop_master(dev, file_priv);
 out_unlock:
 	mutex_unlock(&dev->master_mutex);
-- 
2.25.1

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Re: [PATCH v2 2/2] drm/auth: make drm_{set,drop]master_ioctl symmetrical

[Sam Ravnborg]

Hi Emil.
On Sat, May 30, 2020 at 01:46:40PM +0100, Emil Velikov wrote:
> Currently the ret handling is all over the place - with two redundant
> assignments and another one addressed earlier.
> 
> Use the exact same flow in both functions.
> 
> v2: straighten the code flow, instead of just removing the assignments
Now even I should be able to follow the flow - thanks :-)

> 
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Cc: Colin Ian King <colin.king@canonical.com>
> Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> ---
> Colin, pretty sure that this should address couple of Coverity warnings.
> Yet I didn't check their web UI thingy.
> ---
>  drivers/gpu/drm/drm_auth.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
> index 4c723e3a689c..f2d46b7ac6f9 100644
> --- a/drivers/gpu/drm/drm_auth.c
> +++ b/drivers/gpu/drm/drm_auth.c
> @@ -215,7 +215,7 @@ drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
>  int drm_setmaster_ioctl(struct drm_device *dev, void *data,
>  			struct drm_file *file_priv)
>  {
> -	int ret = 0;
> +	int ret;
>  
>  	mutex_lock(&dev->master_mutex);
>  
> @@ -272,12 +272,15 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
>  	if (ret)
>  		goto out_unlock;
>  
> -	ret = -EINVAL;
> -	if (!drm_is_current_master(file_priv))
> +	if (!drm_is_current_master(file_priv)) {
> +		ret = -EINVAL;
>  		goto out_unlock;
> +	}
>  
> -	if (!dev->master)
> +	if (!dev->master) {
> +		ret = -EINVAL;
>  		goto out_unlock;
> +	}
>  
>  	if (file_priv->master->lessor != NULL) {
>  		DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
> @@ -285,7 +288,6 @@ int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
>  		goto out_unlock;
>  	}
>  
> -	ret = 0;
>  	drm_drop_master(dev, file_priv);
>  out_unlock:
>  	mutex_unlock(&dev->master_mutex);
> -- 
> 2.25.1
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Re: [PATCH v2 2/2] drm/auth: make drm_{set, drop]master_ioctl symmetrical

[Emil Velikov]

On Sat, 30 May 2020 at 14:18, Sam Ravnborg <sam@ravnborg.org> wrote:
>
> Hi Emil.
> On Sat, May 30, 2020 at 01:46:40PM +0100, Emil Velikov wrote:
> > Currently the ret handling is all over the place - with two redundant
> > assignments and another one addressed earlier.
> >
> > Use the exact same flow in both functions.
> >
> > v2: straighten the code flow, instead of just removing the assignments
> Now even I should be able to follow the flow - thanks :-)
>
Fwiw reading at the code the first couple of times, did confuse the
hell out of me.
So "there is nothing wrong with your television set" :-P

> >
> > Cc: David Airlie <airlied@linux.ie>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Cc: Sam Ravnborg <sam@ravnborg.org>
> > Cc: Colin Ian King <colin.king@canonical.com>
> > Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

Thanks. If you're up for a few more neat patches - check these out [1].

-Emil

[1] https://patchwork.freedesktop.org/series/76967/
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Re: [PATCH v2 2/2] drm/auth: make drm_{set,drop]master_ioctl symmetrical

[Sam Ravnborg]

On Sat, May 30, 2020 at 02:34:10PM +0100, Emil Velikov wrote:
> On Sat, 30 May 2020 at 14:18, Sam Ravnborg <sam@ravnborg.org> wrote:
> >
> > Hi Emil.
> > On Sat, May 30, 2020 at 01:46:40PM +0100, Emil Velikov wrote:
> > > Currently the ret handling is all over the place - with two redundant
> > > assignments and another one addressed earlier.
> > >
> > > Use the exact same flow in both functions.
> > >
> > > v2: straighten the code flow, instead of just removing the assignments
> > Now even I should be able to follow the flow - thanks :-)
> >
> Fwiw reading at the code the first couple of times, did confuse the
> hell out of me.
> So "there is nothing wrong with your television set" :-P
> 
> > >
> > > Cc: David Airlie <airlied@linux.ie>
> > > Cc: Daniel Vetter <daniel@ffwll.ch>
> > > Cc: Sam Ravnborg <sam@ravnborg.org>
> > > Cc: Colin Ian King <colin.king@canonical.com>
> > > Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
> > Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> 
> Thanks. If you're up for a few more neat patches - check these out [1].
> 
> -Emil
> 
> [1] https://patchwork.freedesktop.org/series/76967/

On my backlog. They require, I think, a bit more time.
backlog atm is way too big - but thats a common issue for everyone.

	Sam
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Re: [PATCH v2 1/2] drm: vmwgfx: remove drm_driver::master_set() return typ

[Roland Scheidegger]

Looks like a nice cleanup to me. (No idea if at some point there
actually was a reason for a return value...)

Reviewed-by: Roland Scheidegger <sroland@vmware.com>

Am 30.05.20 um 14:46 schrieb Emil Velikov:
> The function always returns zero (success). Ideally we'll remove it all
> together - although that's requires a little more work.
> 
> For now, we can drop the return type and simplify the drm core code
> surrounding it.
> 
> v2: remove redundant assignment (Sam)
> 
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
> Cc: Roland Scheidegger <sroland@vmware.com>
> Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
> Cc: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> ---
> VMWare team, I'm planning to push this via drm-misc. Review, ack and
> comments are appreciated.
> ---
>  drivers/gpu/drm/drm_auth.c          | 32 +++++++----------------------
>  drivers/gpu/drm/vmwgfx/vmwgfx_drv.c |  8 +++-----
>  include/drm/drm_drv.h               |  4 ++--
>  3 files changed, 12 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
> index 74ce0c29c960..4c723e3a689c 100644
> --- a/drivers/gpu/drm/drm_auth.c
> +++ b/drivers/gpu/drm/drm_auth.c
> @@ -122,27 +122,19 @@ struct drm_master *drm_master_create(struct drm_device *dev)
>  	return master;
>  }
>  
> -static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
> -			  bool new_master)
> +static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
> +			   bool new_master)
>  {
> -	int ret = 0;
> -
>  	dev->master = drm_master_get(fpriv->master);
> -	if (dev->driver->master_set) {
> -		ret = dev->driver->master_set(dev, fpriv, new_master);
> -		if (unlikely(ret != 0)) {
> -			drm_master_put(&dev->master);
> -		}
> -	}
> +	if (dev->driver->master_set)
> +		dev->driver->master_set(dev, fpriv, new_master);
>  
> -	fpriv->was_master = (ret == 0);
> -	return ret;
> +	fpriv->was_master = true;
>  }
>  
>  static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
>  {
>  	struct drm_master *old_master;
> -	int ret;
>  
>  	lockdep_assert_held_once(&dev->master_mutex);
>  
> @@ -157,22 +149,12 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
>  	fpriv->is_master = 1;
>  	fpriv->authenticated = 1;
>  
> -	ret = drm_set_master(dev, fpriv, true);
> -	if (ret)
> -		goto out_err;
> +	drm_set_master(dev, fpriv, true);
>  
>  	if (old_master)
>  		drm_master_put(&old_master);
>  
>  	return 0;
> -
> -out_err:
> -	/* drop references and restore old master on failure */
> -	drm_master_put(&fpriv->master);
> -	fpriv->master = old_master;
> -	fpriv->is_master = 0;
> -
> -	return ret;
>  }
>  
>  /*
> @@ -265,7 +247,7 @@ int drm_setmaster_ioctl(struct drm_device *dev, void *data,
>  		goto out_unlock;
>  	}
>  
> -	ret = drm_set_master(dev, file_priv, false);
> +	drm_set_master(dev, file_priv, false);
>  out_unlock:
>  	mutex_unlock(&dev->master_mutex);
>  	return ret;
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> index c2247a893ed4..470428387878 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> @@ -1129,9 +1129,9 @@ static long vmw_compat_ioctl(struct file *filp, unsigned int cmd,
>  }
>  #endif
>  
> -static int vmw_master_set(struct drm_device *dev,
> -			  struct drm_file *file_priv,
> -			  bool from_open)
> +static void vmw_master_set(struct drm_device *dev,
> +			   struct drm_file *file_priv,
> +			   bool from_open)
>  {
>  	/*
>  	 * Inform a new master that the layout may have changed while
> @@ -1139,8 +1139,6 @@ static int vmw_master_set(struct drm_device *dev,
>  	 */
>  	if (!from_open)
>  		drm_sysfs_hotplug_event(dev);
> -
> -	return 0;
>  }
>  
>  static void vmw_master_drop(struct drm_device *dev,
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index bb924cddc09c..835c38a76ef6 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -311,8 +311,8 @@ struct drm_driver {
>  	 *
>  	 * Called whenever the minor master is set. Only used by vmwgfx.
>  	 */
> -	int (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
> -			  bool from_open);
> +	void (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
> +			   bool from_open);
>  	/**
>  	 * @master_drop:
>  	 *
> 

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Re: [PATCH v2 1/2] drm: vmwgfx: remove drm_driver::master_set() return typ

[Emil Velikov]

On Wed, 3 Jun 2020 at 19:37, Roland Scheidegger <sroland@vmware.com> wrote:
>
> Looks like a nice cleanup to me. (No idea if at some point there
> actually was a reason for a return value...)
>
It was required up-to quite recently actually:

commit 9c84aeba67cce6514374f134c9ce2c5f35ac3831
Author: Thomas Hellstrom <thellstrom@vmware.com>
AuthorDate: Tue May 28 08:08:55 2019 +0200
Commit:     Thomas Hellstrom <thellstrom@vmware.com>
CommitDate: Thu Aug 15 08:39:27 2019 +0200

    drm/vmwgfx: Kill unneeded legacy security features

> Reviewed-by: Roland Scheidegger <sroland@vmware.com>
>
Thank you. Will push to drm-misc in a moment.

-Emil
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Re: [PATCH v2 1/2] drm: vmwgfx: remove drm_driver::master_set() return typ

[Emil Velikov]

On Fri, 5 Jun 2020 at 15:07, Emil Velikov <emil.l.velikov@gmail.com> wrote:
>
> On Wed, 3 Jun 2020 at 19:37, Roland Scheidegger <sroland@vmware.com> wrote:
> >
> > Looks like a nice cleanup to me. (No idea if at some point there
> > actually was a reason for a return value...)
> >
> It was required up-to quite recently actually:
>
> commit 9c84aeba67cce6514374f134c9ce2c5f35ac3831
> Author: Thomas Hellstrom <thellstrom@vmware.com>
> AuthorDate: Tue May 28 08:08:55 2019 +0200
> Commit:     Thomas Hellstrom <thellstrom@vmware.com>
> CommitDate: Thu Aug 15 08:39:27 2019 +0200
>
>     drm/vmwgfx: Kill unneeded legacy security features
>
> > Reviewed-by: Roland Scheidegger <sroland@vmware.com>
> >
> Thank you. Will push to drm-misc in a moment.
>
... and finally pushed to drm-misc/next.

Thanks again.
-Emil
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