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From: Chris Wilson <chris@chris-wilson.co.uk>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Julia Lawall <julia.lawall@lip6.fr>
Subject: Re: [Intel-gfx] [PATCH 12/14] drm: Move master pointer from drm_minor to drm_device
Date: Wed, 15 Jun 2016 13:10:35 +0100	[thread overview]
Message-ID: <20160615121035.GP4184@nuc-i3427.alporthouse.com> (raw)
In-Reply-To: <1465930269-7883-13-git-send-email-daniel.vetter@ffwll.ch>

On Tue, Jun 14, 2016 at 08:51:07PM +0200, Daniel Vetter wrote:
> There can only be one current master, and it's for the overall device.
> Render/control minors don't support master-based auth at all.
> 
> This simplifies the master logic a lot, at least in my eyes: All these
> additional pointer chases are just confusing.

One master for the device, on the struct drm_device, as opposed to hidden
behind the first of three minors, makes sense.

> @@ -128,13 +128,13 @@ static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
>  	lockdep_assert_held_once(&dev->master_mutex);
>  
>  	/* create a new master */
> -	fpriv->minor->master = drm_master_create(fpriv->minor->dev);
> -	if (!fpriv->minor->master)
> +	dev->master = drm_master_create(dev);
> +	if (!dev->master)
>  		return -ENOMEM;
>  
>  	/* take another reference for the copy in the local file priv */
>  	old_master = fpriv->master;
> -	fpriv->master = drm_master_get(fpriv->minor->master);
> +	fpriv->master = drm_master_get(dev->master);
>  
>  	if (dev->driver->master_create) {
>  		ret = dev->driver->master_create(dev, fpriv->master);

> @@ -234,10 +234,10 @@ int drm_master_open(struct drm_file *file_priv)
>  	/* if there is no current master make this fd it, but do not create
>  	 * any master object for render clients */
>  	mutex_lock(&dev->master_mutex);
> -	if (!file_priv->minor->master)
> +	if (!dev->master)
>  		ret = drm_new_set_master(dev, file_priv);
>  	else
> -		file_priv->master = drm_master_get(file_priv->minor->master);
> +		file_priv->master = drm_master_get(dev->master);
>  	mutex_unlock(&dev->master_mutex);

You could take the opportunity to make this a bit simpler:

	if (!READ_ONCE(dev->master)) {
		int ret;

		ret = 0;
		mutex_lock(&dev->master_mutex);
		if (!dev->master)
			ret = drm_new_master(dev);
		mutex_unlock(&dev->master_mutex);
		if (ret)
			return ret;
	}

	file_priv->master = drm_master_get(dev->master);
	return 0;

Just to straighten out the kref dance.

>  
>  	return ret;
> @@ -271,11 +271,11 @@ void drm_master_release(struct drm_file *file_priv)
>  		mutex_unlock(&dev->struct_mutex);
>  	}
>  
> -	if (file_priv->minor->master == file_priv->master) {
> +	if (dev->master == file_priv->master) {
>  		/* drop the reference held my the minor */
>  		if (dev->driver->master_drop)
>  			dev->driver->master_drop(dev, file_priv, true);
> -		drm_master_put(&file_priv->minor->master);
> +		drm_master_put(&dev->master);

This still makes me uneasy. This is not equivalent to dropmaster_ioctl
and subsequent setmaster_ioctl will fail as dev->master is still
assigned (but the owner has gone).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

  reply	other threads:[~2016-06-15 12:10 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-14 18:50 [PATCH 00/14] Cruft removal around drm_master Daniel Vetter
2016-06-14 18:50 ` [PATCH 01/14] drm: Nuke legacy maps debugfs files Daniel Vetter
2016-06-15 11:23   ` Chris Wilson
2016-06-15 12:00   ` Emil Velikov
2016-06-14 18:50 ` [PATCH 02/14] drm: Hide hw.lock cleanup in filp->release better Daniel Vetter
2016-06-15 11:26   ` [Intel-gfx] " Chris Wilson
2016-06-15 12:10   ` Emil Velikov
2016-06-14 18:50 ` [PATCH 03/14] drm: Link directly from drm_master to drm_device Daniel Vetter
2016-06-15 11:29   ` Chris Wilson
2016-06-15 12:50   ` [Intel-gfx] " Emil Velikov
2016-06-15 15:45     ` Daniel Vetter
2016-06-16 20:04       ` Emil Velikov
2016-06-14 18:50 ` [PATCH 04/14] drm: Move master functions into drm_auth.c Daniel Vetter
2016-06-15 11:31   ` Chris Wilson
2016-06-15 15:47     ` Daniel Vetter
2016-06-14 18:51 ` [PATCH 05/14] drm: Extract drm_master_open Daniel Vetter
2016-06-15 11:41   ` [Intel-gfx] " Chris Wilson
2016-06-14 18:51 ` [PATCH 06/14] drm: Extract drm_master_relase Daniel Vetter
2016-06-15 11:43   ` [Intel-gfx] " Chris Wilson
2016-06-16  8:18     ` Daniel Vetter
2016-06-14 18:51 ` [PATCH 07/14] drm: Only do the hw.lock cleanup in master_relase for !MODESET Daniel Vetter
2016-06-15 11:48   ` Chris Wilson
2016-06-15 15:49     ` [Intel-gfx] " Daniel Vetter
2016-06-14 18:51 ` [PATCH 08/14] drm: Move authmagic cleanup into drm_master_release Daniel Vetter
2016-06-15 11:51   ` Chris Wilson
2016-06-14 18:51 ` [PATCH 09/14] drm: Protect authmagic with master_mutex Daniel Vetter
2016-06-15 11:54   ` [Intel-gfx] " Chris Wilson
2016-06-15 15:52     ` Daniel Vetter
2016-06-14 18:51 ` [PATCH 10/14] drm: Mark authmagic ioctls as unlocked Daniel Vetter
2016-06-15 11:55   ` [Intel-gfx] " Chris Wilson
2016-06-14 18:51 ` [PATCH 11/14] drm: Mark set/drop master ioctl " Daniel Vetter
2016-06-15 11:56   ` [Intel-gfx] " Chris Wilson
2016-06-14 18:51 ` [PATCH 12/14] drm: Move master pointer from drm_minor to drm_device Daniel Vetter
2016-06-15 12:10   ` Chris Wilson [this message]
2016-06-15 16:01     ` Daniel Vetter
2016-06-15 16:33       ` Chris Wilson
2016-06-15 19:54         ` [Intel-gfx] " Daniel Vetter
2016-06-14 18:51 ` [PATCH 13/14] drm: Clean up drm_crtc.h Daniel Vetter
2016-06-14 18:51 ` [PATCH 14/14] drm: Use dev->name as fallback for dev->unique Daniel Vetter
2016-06-15  5:42 ` ✓ Ro.CI.BAT: success for Cruft removal around drm_master Patchwork

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