linux/drivers/gpu/drm
Dave Airlie 219b47339c drm/prime: keep a reference from the handle to exported dma-buf (v6)
Currently we have a problem with this:
1. i915: create gem object
2. i915: export gem object to prime
3. radeon: import gem object
4. close prime fd
5. radeon: unref object
6. i915: unref object

i915 has an imported object reference in its file priv, that isn't
cleaned up properly until fd close. The reference gets added at step 2,
but at step 6 we don't have enough info to clean it up.

The solution is to take a reference on the dma-buf when we export it,
and drop the reference when the gem handle goes away.

So when we export a dma_buf from a gem object, we keep track of it
with the handle, we take a reference to the dma_buf. When we close
the handle (i.e. userspace is finished with the buffer), we drop
the reference to the dma_buf, and it gets collected.

This patch isn't meant to fix any other problem or bikesheds, and it doesn't
fix any races with other scenarios.

v1.1: move export symbol line back up.

v2: okay I had to do a bit more, as the first patch showed a leak
on one of my tests, that I found using the dma-buf debugfs support,
the problem case is exporting a buffer twice with the same handle,
we'd add another export handle for it unnecessarily, however
we now fail if we try to export the same object with a different gem handle,
however I'm not sure if that is a case I want to support, and I've
gotten the code to WARN_ON if we hit something like that.

v2.1: rebase this patch, write better commit msg.
v3: cleanup error handling, track import vs export in linked list,
these two patches were separate previously, but seem to work better
like this.
v4: danvet is correct, this code is no longer useful, since the buffer
better exist, so remove it.
v5: always take a reference to the dma buf object, import or export.
(Imre Deak contributed this originally)
v6: square the circle, remove import vs export tracking now
that there is no difference

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
2013-05-01 09:30:15 +10:00
..
ast Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2013-02-25 16:46:44 -08:00
cirrus Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2013-02-25 16:46:44 -08:00
exynos drm/exynos: Don't blend mixer layer 0 2013-04-29 14:40:20 +09:00
gma500 Merge branch 'gma500-fixes' of git://github.com/patjak/drm-gma500 into drm-next 2013-04-26 10:16:10 +10:00
i2c
i810
i915 Merge branch 'drm-intel-fixes' of git://people.freedesktop.org/~danvet/drm-intel into drm-next 2013-04-30 09:58:17 +10:00
mga
mgag200 drm/mgag200: Remove extra variable assigns 2013-04-30 09:57:23 +10:00
nouveau drm/nouveau/fifo: implement channel creation event generation 2013-04-26 15:38:17 +10:00
omapdrm drm/omap: add statics to a few structs 2013-04-11 13:26:06 +03:00
qxl drivers, drm: fix qxl build error when debugfs is disabled 2013-04-30 10:00:27 +10:00
r128
radeon drm/radeon: disable UVD advanced semaphore mode 2013-04-23 18:04:01 -04:00
savage
shmobile drm/shmobile: Fix race condition between page flip request and handler 2013-04-26 10:21:57 +10:00
sis drm/sis: convert to idr_alloc() 2013-02-27 19:10:16 -08:00
tdfx
tilcdc drm/tilcdc: use only a single module device table 2013-04-26 10:18:46 +10:00
ttm drm: use vma_pages() to replace (vm_end - vm_start) >> PAGE_SHIFT 2013-04-16 13:14:00 +10:00
udl Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
via drm/via: convert to idr_alloc() 2013-02-27 19:10:16 -08:00
vmwgfx drm/vmwgfx: convert to idr_alloc() 2013-02-27 19:10:16 -08:00
ati_pcigart.c
drm_agpsupport.c
drm_auth.c
drm_buffer.c
drm_bufs.c
drm_cache.c lib/scatterlist: sg_page_iter: support sg lists w/o backing pages 2013-03-27 17:13:44 +01:00
drm_context.c drm: convert to idr_alloc() 2013-02-27 19:10:15 -08:00
drm_crtc_helper.c drm: Perform a full mode set when the pixel format changed 2013-04-22 19:48:30 +10:00
drm_crtc.c drm: Kill user_modes list and the associated ioctls 2013-04-30 10:03:07 +10:00
drm_debugfs.c
drm_dma.c
drm_dp_helper.c
drm_drv.c drm: Kill user_modes list and the associated ioctls 2013-04-30 10:03:07 +10:00
drm_edid_load.c drm: Add 1600x1200 (UXGA) screen resolution to the built-in EDIDs 2013-04-12 14:06:16 +10:00
drm_edid.c drm/edid: Check both 60Hz and 59.94Hz when looking for a CEA mode 2013-04-26 10:25:54 +10:00
drm_encoder_slave.c
drm_fb_cma_helper.c
drm_fb_helper.c drm: add initial_config function to fb helper 2013-03-26 21:32:53 +01:00
drm_fops.c drm: correctly restore mappings if drm_open fails 2013-04-03 06:44:38 +10:00
drm_gem_cma_helper.c
drm_gem.c drm/prime: keep a reference from the handle to exported dma-buf (v6) 2013-05-01 09:30:15 +10:00
drm_global.c
drm_hashtab.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
drm_info.c
drm_ioc32.c
drm_ioctl.c
drm_irq.c
drm_lock.c
drm_memory.c
drm_mm.c
drm_modes.c drm: Add drm_mode_equal_no_clocks() 2013-04-26 10:25:09 +10:00
drm_pci.c drm: Silence some sparse warnings 2013-04-30 10:02:25 +10:00
drm_platform.c
drm_prime.c drm/prime: keep a reference from the handle to exported dma-buf (v6) 2013-05-01 09:30:15 +10:00
drm_proc.c
drm_scatter.c
drm_stub.c drm: convert to idr_alloc() 2013-02-27 19:10:15 -08:00
drm_sysfs.c
drm_trace_points.c
drm_trace.h
drm_usb.c
drm_vm.c drm: export drm_vm_open_locked 2013-04-26 10:20:00 +10:00
Kconfig drm/tegra: Move drm to live under host1x 2013-04-22 12:39:11 +02:00
Makefile drm/tegra: Move drm to live under host1x 2013-04-22 12:39:11 +02:00
README.drm

************************************************************
* For the very latest on DRI development, please see:      *
*     http://dri.freedesktop.org/                          *
************************************************************

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