Render nodes provide an API for userspace to use non-privileged GPU
commands without any running DRM-Master. It is useful for offscreen
rendering, GPGPU clients, and normal render clients which do not perform
modesetting.

Compared to legacy clients, render clients no longer need any
authentication to perform client ioctls. Instead, user-space controls
render/client access to GPUs via filesystem access-modes on the
render-node. Once a render-node was opened, a client has full access to
the client/render operations on the GPU. However, no modesetting or ioctls
that affect global state are allowed on render nodes.

To prevent privilege-escalation, drivers must explicitly state that they
support render nodes. They must mark their render-only ioctls as
DRM_RENDER_ALLOW so render clients can use them. Furthermore, they must
support clients without any attached master.

If filesystem access-modes are not enough for fine-grained access control
to render nodes (very unlikely, considering the versaitlity of FS-ACLs),
you may still fall-back to fd-passing from server to client (which allows
arbitrary access-control). However, note that revoking access is
currently impossible and unlikely to get implemented.

Note: Render clients no longer have any associated DRM-Master as they are
supposed to be independent of any server state. DRM core highly depends on
file_priv->master to be non-NULL for modesetting/ctx/etc. commands.
Therefore, drivers must be very careful to not require DRM-Master if they
support DRIVER_RENDER.

So far render-nodes are protected by "drm_rnodes". As long as this
module-parameter is not set to 1, a driver will not create render nodes.
This allows us to experiment with the API a bit before we stabilize it.

v2: drop insecure GEM_FLINK to force use of dmabuf
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

HDMI_IDENTIFIER was felt too generic, rename it to what it is, the IEEE
OUI corresponding to HDMI Licensing, LLC.

http://standards.ieee.org/develop/regauth/oui/oui.txt

Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

With all the common infoframe bits now in place, we can finally write
the vendor specific infoframes in our driver.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

This can then be used by DRM drivers to setup their vendor infoframes.

v2: Fix hmdi typo (Simon Farnsworth)
v3: Adapt to the hdmi_vendor_infoframe rename
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NSimon Farnsworth <simon.farnsworth@onelan.co.uk>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

We just got rid of the version of hdmi_vendor_infoframe that had a byte
array for anyone to poke at. It's now time to shuffle around the naming
of hdmi_hdmi_infoframe to make hdmi_vendor_infoframe become the HDMI
vendor specific structure.

Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

With this last bit, hdmi_infoframe_pack() is now able to pack any
infoframe we support.

At the same time, because it's impractical to make two commits out of
this, we get rid of the version that encourages the open coding of the
vendor infoframe packing. We can do so because the only user of this API
has been ported in:

  Author: Damien Lespiau <damien.lespiau@intel.com>
  Date:   Mon Aug 12 18:08:37 2013 +0100

      gpu: host1x: Port the HDMI vendor infoframe code the common helpers

v2: Change oui to be an unsigned int (Ville Syrjälä)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

We'll need the HDMI OUI for the HDMI vendor infoframe data, so let's
move the DRM one to hdmi.h, might as well use the hdmi header to store
some hdmi defines.

(Note that, in fact, infoframes are part of the CEA-861 standard, and
only the HDMI vendor specific infoframe is special to HDMI, but
details..)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

I just wrote the bits to define and pack HDMI vendor specific infoframe.
Port the host1x driver to use those so I can refactor the infoframe code
a bit more.

This changes the length of the infoframe payload from 6 to 5, which is
enough for the "frame packing" stereo format.

v2: Pimp up the commit message with the note about the length
    (Ville Syrjälä)

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Terje Bergström <tbergstrom@nvidia.com>
Cc: linux-tegra@vger.kernel.org
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

Provide the same programming model than the other infoframe types.

The generic _pack() function can't handle those yet as we need to move
the vendor OUI in the generic hdmi_vendor_infoframe structure to know
which kind of vendor infoframe we are dealing with.

v2: Fix the value of Side-by-side (half), hmdi typo, pack 3D_Ext_Data
    (Ville Syrjälä)
v3: Future proof the sending of 3D_Ext_Data (Ville Syrjälä), Fix
    multi-lines comment style (Thierry Reding)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

Just like:

  Author: Damien Lespiau <damien.lespiau@intel.com>
  Date:   Mon Aug 12 11:53:24 2013 +0100

      video/hdmi: Don't let the user of this API create invalid infoframes

But this time for the horizontal/vertical bar data present bits.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

To set the active aspect ratio value in the AVI infoframe today, you not
only have to set the active_aspect field, but also the active_info_valid
bit. Out of the 1 user of this API, we had 100% misuse, forgetting the
_valid bit. This was fixed in:

  Author: Damien Lespiau <damien.lespiau@intel.com>
  Date:   Tue Aug 6 20:32:17 2013 +0100

      drm: Don't generate invalid AVI infoframes for CEA modes

We can do better and derive the _valid bit from the user wanting to set
the active aspect ratio.

v2: Fix multi-lines comment style (Thierry Reding)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

v2: Fix hmdi typo (Simon Farnsworth, Ville Syrjälä)
Suggested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NSimon Farnsworth <simon.farnsworth@onelan.co.uk>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

HDMI 1.4 adds 4 "4k x 2k" modes in the the CEA vendor specific block.

With this commit, we now parse this block and expose the 4k modes that
we find there.

v2: Fix the "4096x2160" string (nice catch!), add comments about
    do_hdmi_vsdb_modes() arguments and make it clearer that offset is
    relative to the end of the required fields of the HDMI VSDB
    (Ville Syrjälä)

v3: Fix 'Unknow' typo (Simon Farnsworth)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Tested-by: NCancan Feng <cancan.feng@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67030Reviewed-by: NSimon Farnsworth <simon.farnsworth@onelan.co.uk>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

A few styles issues have crept in here, fix them before touching this
code again.

v2: constify arguments that can be (Ville Syrjälä)
v3: constify, but better (Ville Syrjälä)
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

This function is only used inside drm_edid.c.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NDave Airlie <airlied@gmail.com>

This hooks nouveau up to the runtime PM system to enable
dynamic power management for secondary GPUs in switchable
and optimus laptops.

a) rewrite suspend/resume printks to hide them during dynamic s/r
to avoid cluttering logs
b) add runtime pm suspend to irq handler, crtc display, ioctl handler,
connector status,
c) handle hdmi audio dynamic power on/off using magic register.

v0.5:
make sure we hit D3 properly
fix fbdev_set_suspend locking interaction, we only will poweroff if we have no
active crtcs/fbcon anyways.
add reference for active crtcs.
sprinkle mark last busy for autosuspend timeout

v0.6:
allow more flexible debugging - to avoid log spam
add option to enable/disable dynpm
got to D3Cold

v0.7:
add hdmi audio support.

v0.8:
call autosuspend from idle, so pci config space access doesn't go straight
back to sleep, this makes starting X faster.
only signal usage if we actually handle the irq, otherwise usb keeps us awake.
fix nv50 display active powerdown

v0.9:
use masking function to enable hdmi audio
set busy when we fail to suspend
Signed-off-by: NDave Airlie <airlied@redhat.com>

Signed-off-by: NDave Airlie <airlied@redhat.com>

Add support for HDMI audio device on VGA cards that powerdown
to D3cold using non-standard ACPI/PCI infrastructure (optimus).

This does a couple of things to make it work:

a) add a set of power ops for the hdmi domain, and enables them
via vga_switcheroo when we are a switcheroo controlled card. This
just replaces the runtime resume operation so that when the card
is in D3cold the userspace pci config space access via sysfs,
the vga switcheroon runtime resume gets called first and it calls
the GPU resume callback before calling the sound card runtime
resume.

b) standard ACPI/PCI stacks won't put a device into D3cold without
an ACPI handle, but since the hdmi audio devices on gpus don't have
an ACPI handle, we need to manually force the device into D3cold
after suspend from the switcheroo path only.

c) don't try and do runtime s/r when the GPU is off.

d) call runtime suspend/resume during switcheroo suspend/resume
this is to make sure the runtime stack knows to try and resume
the hdmi audio device for pci config space access.

v2: fix incorrect runtime call suspend->resume.

v3: rework irq handler to avoid false irq when we are resuming
but haven't runtime resumed yet, don't bother trying D3cold,
it won't work, just set it manually ourselves, move runtime s/r
calls outside the main s/r hook. enable dnyamic pm properly by
dropping reference.

v4: put back irq handler check just wrap it with cap check
Acked-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>

For optimus and powerxpress muxless we really want the GPU
driver deciding when to power up/down the GPU, not userspace.

This adds the ability for a driver to dynamically power up/down
the GPU and remove the switcheroo from controlling it, the
switcheroo reports the dynamic state to userspace also.

It also adds 2 power domains, one for machine where the power
switch is controlled outside the GPU D3 state, so the powerdown
ordering is done correctly, and the second for the hdmi audio
device to make sure it can resume for PCI config space accesses.

v1.1: fix build with switcheroo off

v2: add power domain support for radeon and v1 nvidia dsms
v2.1: fix typo in off case

v3: add audio power domain for hdmi audio + misc audio fixes

v4: use PCI_SLOT macro, drop power reference on hdmi audio resume
failure also.
Signed-off-by: NDave Airlie <airlied@redhat.com>

Merge the MSM driver from Rob Clark
* 'drm-next' of git://people.freedesktop.org/~robclark/linux:
  drm/msm: add basic hangcheck/recovery mechanism
  drm/msm: add a3xx gpu support
  drm/msm: add register definitions for gpu
  drm/msm: basic KMS driver for snapdragon
  drm/msm: add register definitions

GEM does already a good job in tracking access to gem buffers via handles
and drm_vma access management. However, TTM drivers currently do not
verify this during mmap().

TTM provides the verify_access() callback to test this. So fix all drivers
to actually call into gem+vma to verify access instead of always returning
0.

All drivers assume that user-space can only get access to TTM buffers via
GEM handles. So whenever the verify_access() callback is called from
ttm_bo_mmap(), the buffer must have a valid embedded gem object. This is
true for all TTM+GEM drivers. But that's why this patch doesn't touch pure
TTM drivers (ie, vmwgfx).

v2: Switch to drm_vma_node_verify_access() to correctly return -EACCES if
    access was denied.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

We implement automatic vma mmap() access management for all drivers using
gem_mmap. We use the vma manager to add each open-file that creates a
gem-handle to the vma-node of the underlying gem object. Once the handle
is destroyed, we drop the open-file again.

This allows us to use drm_vma_node_is_allowed() on _any_ gem object to see
whether an open-file is granted access. In drm_gem_mmap() we use this to
verify that unprivileged users cannot guess gem offsets and map arbitrary
buffers.

Note that this manages access for _all_ gem users (also TTM+GEM), but the
actual access checks are only done for drm_gem_mmap(). TTM drivers use the
TTM mmap helpers, which need to do that separately.
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The VMA offset manager uses a device-global address-space. Hence, any
user can currently map any offset-node they want. They only need to guess
the right offset. If we wanted per open-file offset spaces, we'd either
need VM_NONLINEAR mappings or multiple "struct address_space" trees. As
both doesn't really scale, we implement access management in the VMA
manager itself.

We use an rb-tree to store open-files for each VMA node. On each mmap
call, GEM, TTM or the drivers must check whether the current user is
allowed to map this file.

We add a separate lock for each node as there is no generic lock available
for the caller to protect the node easily.

As we currently don't know whether an object may be used for mmap(), we
have to do access management for all objects. If it turns out to slow down
handle creation/deletion significantly, we can optimize it in several
ways:
 - Most times only a single filp is added per bo so we could use a static
   "struct file *main_filp" which is checked/added/removed first before we
   fall back to the rbtree+drm_vma_offset_file.
   This could be even done lockless with rcu.
 - Let user-space pass a hint whether mmap() should be supported on the
   bo and avoid access-management if not.
 - .. there are probably more ideas once we have benchmarks ..

v2: add drm_vma_node_verify_access() helper
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

A basic, no-frills recovery mechanism in case the gpu gets wedged.  We
could try to be a bit more fancy and restart the next submit after the
one that got wedged, but for now keep it simple.  This is enough to
recover things if, for example, the gpu hangs mid way through a piglit
run.
Signed-off-by: NRob Clark <robdclark@gmail.com>

Add initial support for a3xx 3d core.

So far, with hardware that I've seen to date, we can have:
 + zero, one, or two z180 2d cores
 + a3xx or a2xx 3d core, which share a common CP (the firmware
   for the CP seems to implement some different PM4 packet types
   but the basics of cmdstream submission are the same)

Which means that the eventual complete "class" hierarchy, once
support for all past and present hw is in place, becomes:
 + msm_gpu
   + adreno_gpu
     + a3xx_gpu
     + a2xx_gpu
   + z180_gpu

This commit splits out the parts that will eventually be common
between a2xx/a3xx into adreno_gpu, and the parts that are even
common to z180 into msm_gpu.

Note that there is no cmdstream validation required.  All memory access
from the GPU is via IOMMU/MMU.  So as long as you don't map silly things
to the GPU, there isn't much damage that the GPU can do.
Signed-off-by: NRob Clark <robdclark@gmail.com>

Generated from rnndb files in:

https://github.com/freedreno/envytools

Keep this split out as a separate commit to make it easier to review the
actual driver.
Signed-off-by: NRob Clark <robdclark@gmail.com>

The snapdragon chips have multiple different display controllers,
depending on which chip variant/version.  (As far as I can tell, current
devices have either MDP3 or MDP4, and upcoming devices have MDSS.)  And
then external to the display controller are HDMI, DSI, etc. blocks which
may be shared across devices which have different display controller
blocks.

To more easily add support for different display controller blocks, the
display controller specific bits are split out into a "kms" module,
which provides the kms plane/crtc/encoder objects.

The external HDMI, DSI, etc. blocks are part encoder, and part connector
currently.  But I think I will pull in the drm_bridge patches from
chromeos tree, and split them into a bridge+connector, with the
registers that need to be set in modeset handled by the bridge.  This
would remove the 'msm_connector' base class.  But some things need to be
double checked to make sure I could get the correct ON/OFF sequencing..

This patch adds support for mdp4 crtc (including hw cursor), dtv encoder
(part of MDP4 block), and hdmi.
Signed-off-by: NRob Clark <robdclark@gmail.com>

Generated from rnndb files in:

https://github.com/freedreno/envytools

Keep this split out as a separate commit to make it easier to review the
actual driver.
Signed-off-by: NRob Clark <robdclark@gmail.com>

Here's some gma500 unifying and cleanups for drm-next. There is more stuff in
the pipe for 3.12 but I'd like to get these out of the way first.

* 'gma500-next' of git://github.com/patjak/drm-gma500: (35 commits)
  drm/gma500/cdv: Add and hook up chip op for disabling sr
  drm/gma500/cdv: Add and hook up chip op for watermarks
  drm/gma500: Rename psb_intel_encoder to gma_encoder
  drm/gma500: Rename psb_intel_connector to gma_connector
  drm/gma500: Rename psb_intel_crtc to gma_crtc
  drm/gma500/cdv: Convert to generic set_config()
  drm/gma500/psb: Convert to generic set_config()
  drm/gma500: Add generic set_config() function
  drm/gma500/cdv: Convert to generic save/restore
  drm/gma500/psb: Convert to generic save/restore
  drm/gma500: Add generic crtc save/restore funcs
  drm/gma500: Convert to generic encoder funcs
  drm/gma500: Add generic encoder functions
  drm/gma500/psb: Convert to generic cursor funcs
  drm/gma500/cdv: Convert to generic cursor funcs
  drm/gma500: Add generic cursor functions
  drm/gma500/psb: Convert to generic crtc->destroy
  drm/gma500/mdfld: Use identical generic crtc funcs
  drm/gma500/oak: Use identical generic crtc funcs
  drm/gma500/psb: Convert to gma_crtc_dpms()
  ...

... not only when the dma-buf is freshly created. In contrived
examples someone else could have exported/imported the dma-buf already
and handed us the gem object with a flink name. If such on object gets
reexported as a dma_buf we won't have it in the handle cache already,
which breaks the guarantee that for dma-buf imports we always hand
back an existing handle if there is one.

This is exercised by igt/prime_self_import/with_one_bo_two_files

Now if we extend the locked sections just a notch more we can also
plug th racy buf/handle cache setup in handle_to_fd:

If evil userspace races a concurrent gem close against a prime export
operation we can end up tearing down the gem handle before the dma buf
handle cache is set up. When handle_to_fd gets around to adding the
handle to the cache there will be no one left to clean it up,
effectily leaking the bo (and the dma-buf, since the handle cache
holds a ref on the dma-buf):

Thread A			Thread B

handle_to_fd:

lookup gem object from handle
creates new dma_buf

				gem_close on the same handle
				obj->dma_buf is set, but file priv buf
				handle cache has no entry

				obj->handle_count drops to 0

drm_prime_add_buf_handle sets up the handle cache

-> We have a dma-buf reference in the handle cache, but since the
handle_count of the gem object already dropped to 0 no on will clean
it up. When closing the drm device fd we'll hit the WARN_ON in
drm_prime_destroy_file_private.

The important change is to extend the critical section of the
filp->prime.lock to cover the gem handle lookup. This serializes with
a concurrent gem handle close.

This leak is exercised by igt/prime_self_import/export-vs-gem_close-race
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

... and move it to the top of the function to avoid a forward
declaration.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

with the reworking semantics and locking of the obj->dma_buf pointer
this pointer is always set as long as there's still a gem handle
around and a dma_buf associated with this gem object.

Also, the per file-priv lookup-cache for dma-buf importing is also
unified between foreign and native objects.

Hence we don't need to special case the clean any more and can simply
drop the clause which only runs for foreing objects, i.e. with
obj->import_attach set.

Note that with this change (actually with the previous one to always
set up obj->dma_buf even for foreign objects) it is no longer required
to set obj->import_attach when importing a foreing object. So update
comments accordingly, too.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The export dma-buf cache is semantically similar to an flink name. So
semantically it makes sense to treat it the same and remove the name
(i.e. the dma_buf pointer) and its references when the last gem handle
disappears.

Again we need to be careful, but double so: Not just could someone
race and export with a gem close ioctl (so we need to recheck
obj->handle_count again when assigning the new name), but multiple
exports can also race against each another. This is prevented by
holding the dev->object_name_lock across the entire section which
touches obj->dma_buf.

With the new scheme we also need to reinstate the obj->dma_buf link at
import time (in case the only reference userspace has held in-between
was through the dma-buf fd and not through any native gem handle). For
simplicity we don't check whether it's a native object but
unconditionally set up that link - with the new scheme of removing the
obj->dma_buf reference when the last handle disappears we can do that.

To make it clear that this is not just for exported buffers anymore
als rename it from export_dma_buf to dma_buf.

To make sure that now one can race a fd_to_handle or handle_to_fd with
gem_close we use the same tricks as in flink of extending the
dev->object_name_locking critical section. With this change we finally
have a guaranteed 1:1 relationship (at least for native objects)
between gem objects and dma-bufs, even accounting for races (which can
happen since the dma-buf itself holds a reference while in-flight).

This prevent igt/prime_self_import/export-vs-gem_close-race from
Oopsing the kernel. There is still a leak though since the per-file
priv dma-buf/handle cache handling is racy. That will be fixed in a
later patch.

v2: Remove the bogus dma_buf_put from the export_and_register_object
failure path if we've raced with the handle count dropping to 0.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

The gem flink name holds a reference onto the object itself, and this
self-reference would prevent an flink'ed object from every being
freed. To break that loop we remove the flink name when the last
userspace handle disappears, i.e. when obj->handle_count reaches 0.

Now in gem_open we drop the dev->object_name_lock between the flink
name lookup and actually adding the handle. This means a concurrent
gem_close of the last handle could result in the flink name getting
reaped right inbetween, i.e.

Thread 1		Thread 2
gem_open		gem_close

flink -> obj lookup
			handle_count drops to 0
			remove flink name
create_handle
handle_count++

If someone now flinks this object again, we'll get a new flink name.

We can close this race by removing the lock dropping and making the
entire lookup+handle_create sequence atomic. Unfortunately to still be
able to share the handle_create logic this requires a
handle_create_tail function which drops the lock - we can't hold the
object_name_lock while calling into a driver's ->gem_open callback.

Note that for flink fixing this race isn't really important, since
racing gem_open against gem_close is clearly a userspace bug. And no
matter how the race ends, we won't leak any references.

But with dma-buf where the userspace dma-buf fd itself is refcounted
this is a valid sequence and hence we should fix it. Therefore this
patch here is just a warm-up exercise (and for consistency between
flink buffer sharing and dma-buf buffer sharing with self-imports).

Also note that this extension of the critical section in gem_open
protected by dev->object_name_lock only works because it's now a
mutex: A spinlock would conflict with the potential memory allocation
in idr_preload().

This is exercises by igt/gem_flink_race/flink_name.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

I want to wrap the creation of a dma-buf from a gem object in it,
so that the obj->export_dma_buf cache can be atomically filled in.

Instead of creating a new mutex just for that variable I've figured
I can reuse the existing dev->object_name_lock, especially since
the new semantics will exactly mirror the flink obj->name already
protected by that lock.

v2: idr_preload/idr_preload_end is now an atomic section, so need to
move the mutex locking outside.

[airlied: fix up conflict with patch to make debugfs use lock]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

if (!ret) implies that ret == 0, so no need to clear it again. And
explicitly check for ret == 0 to indicate that we're checking an errno
integer.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

When exporting a gem object as a dma-buf the critical section for the
per-fd prime lock is just the adding (and in case of errors, removing)
of the handle to the per-fd lookup cache.

So restrict the critical section to just that part of the function.

This simplifies later reordering.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Part of the function uses the properly-typed dmabuf variable, the
other an untyped void *buf. Kill the later.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

No one outside of drm should use this, the official interfaces are
drm_gem_handle_create and drm_gem_handle_delete. The handle refcounting
is purely an implementation detail of gem.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>

handle_unreference only clears up the obj->name and the reference,
but would leave a dangling handle in the idr. The right thing
to do is to call handle_delete.
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDave Airlie <airlied@redhat.com>