bfb899282f
First convert ->cursor_set to only take the crtc lock, since that seems to be the function with the least amount of state - the core ioctl function doesn't check anything which can change at runtime, so we don't have any object lifetime issues to contend. The only thing which is important is that the driver's implementation doesn't touch any state outside of that single crtc which is not yet properly protected by other locking: - ast: access the global ast->cache_kmap. Luckily we only have on crtc on this driver, so this is fine. Add a comment. - gma500: calls gma_power_begin|and and psb_gtt_pin|unpin, both which have their own locking to protect their state. Everything else is crtc-local. - i915: touches a bit of global gem state, all protected by the One Lock to Rule Them All (dev->struct_mutex). - nouveau: Pre-nv50 is all nice, nv50+ uses the evo channels to queue up all display changes. And some of these channels are device global. But this is fine now since the previous patch introduced an evo channel mutex. - radeon: Uses some indirect register access for cursor updates, but with the previous patches to protect these indirect 2-register access patterns with a spinlock, this should be fine now, too. - vmwgfx: I have no idea how that works - update_cursor_position doesn't take any per-crtc argument and I haven't figured out any other place where this could be set in some form of a side-channel. But vmwgfx definitely has more than one crtc (or at least can register more than one), so I have no idea how this is supposed to not fail with the current code already. Hence take the easy way out and simply acquire all locks (which requires dropping the crtc lock the core acquired for us). That way it's not worse off for consistency than the old code. Reviewed-by: Rob Clark <rob@ti.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
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The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html