dma-buf/dma-fence: fix spelling

Fix spelling mistakes as reported by codespell.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: Christian König <christian.koenig@amd.com>
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20240111041138.30278-1-rdunlap@infradead.org

dma-buf/sync_file: Add SET_DEADLINE ioctl

The initial purpose is for igt tests, but this would also be useful for
compositors that wait until close to vblank deadline to make decisions
about which frame to show.

The igt tests can be found at:

https://gitlab.freedesktop.org/robclark/igt-gpu-tools/-/commits/fence-deadline

v2: Clarify the timebase, add link to igt tests
v3: Use u64 value in ns to express deadline.
v4: More doc

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230823215458.203366-3-robdclark@gmail.com

dma-buf: fix an error pointer vs NULL bug

Smatch detected potential error pointer dereference.

drivers/gpu/drm/drm_syncobj.c:888 drm_syncobj_transfer_to_timeline()
error: 'fence' dereferencing possible ERR_PTR()

The error pointer comes from dma_fence_allocate_private_stub(). One
caller expected error pointers and one expected NULL pointers. Change
it to return NULL and update the caller which expected error pointers,
drm_syncobj_assign_null_handle(), to check for NULL instead.

Fixes: f781f661e8c9 ("dma-buf: keep the signaling time of merged fences v3")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/b09f1996-3838-4fa2-9193-832b68262e43@moroto.mountain

dma-buf: keep the signaling time of merged fences v3

Some Android CTS is testing if the signaling time keeps consistent
during merges.

v2: use the current time if the fence is still in the signaling path and
the timestamp not yet available.
v3: improve comment, fix one more case to use the correct timestamp

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230630120041.109216-1-christian.koenig@amd.com

dma-buf/dma-fence: Add deadline awareness

Add a way to hint to the fence signaler of an upcoming deadline, such as
vblank, which the fence waiter would prefer not to miss. This is to aid
the fence signaler in making power management decisions, like boosting
frequency as the deadline approaches and awareness of missing deadlines
so that can be factored in to the frequency scaling.

v2: Drop dma_fence::deadline and related logic to filter duplicate
deadlines, to avoid increasing dma_fence size. The fence-context
implementation will need similar logic to track deadlines of all
the fences on the same timeline. [ckoenig]
v3: Clarify locking wrt. set_deadline callback
v4: Clarify in docs comment that this is a hint
v5: Drop DMA_FENCE_FLAG_HAS_DEADLINE_BIT.
v6: More docs
v7: Fix typo, clarify past deadlines

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>

dma-buf: actually set signaling bit for private stub fences

In dma_fence_allocate_private_stub() set the signaling bit of the newly
allocated private stub fence rather than the signaling bit of the
shared dma_fence_stub.

Fixes: c85d00d4fd8b ("dma-buf: set signaling bit for the stub fence")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230126002844.339593-1-dakr@redhat.com

dma-buf: actually set signaling bit for private stub fences

In dma_fence_allocate_private_stub() set the signaling bit of the newly
allocated private stub fence rather than the signaling bit of the
shared dma_fence_stub.

Fixes: c85d00d4fd8b ("dma-buf: set signaling bit for the stub fence")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230126002844.339593-1-dakr@redhat.com
(cherry picked from commit 851a4a77a9f6441bd73625fe6dbc29c814ae681f)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

dma-buf: actually set signaling bit for private stub fences

In dma_fence_allocate_private_stub() set the signaling bit of the newly
allocated private stub fence rather than the signaling bit of the
shared dma_fence_stub.

Cc: <stable@vger.kernel.org> # v6.1
Fixes: c85d00d4fd8b ("dma-buf: set signaling bit for the stub fence")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230126002844.339593-1-dakr@redhat.com

dma-buf: fix dma_fence_default_wait() signaling check

That check must now come after grabing the spinlock, not before.

Signed-off-by: Christian König <christian.koenig@amd.com>
Fixes: b96fb1e724ae ("dma-buf: dma_fence_wait must enable signaling")
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220919120618.113332-1-christian.koenig@amd.com

dma-buf: dma_fence_wait must enable signaling

dma_fence_wait() should always enable signaling even
when the fence is already signaled.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220914164321.2156-5-Arvind.Yadav@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-buf: set signaling bit for the stub fence

Here's setting software signaling bit for the stub fence
which is always signaled. If this fence signaling bit is
not set then the AMD GPU scheduler will cause a GPU reset
due to a GPU scheduler cleanup activity timeout.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220914164321.2156-3-Arvind.Yadav@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-buf: Remove the signaled bit status check

Remove the signaled bit status check because it is returning
early when the fence is already signaled and
__dma_fence_enable_signaling is checking the status of signaled
bit again.

Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220914164321.2156-2-Arvind.Yadav@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-buf: add dma_fence_describe and dma_resv_describe v2

Add functions to dump dma_fence and dma_resv objects into a seq_file and
use them for printing the debugfs information.

v2: fix missing include reported by test robot.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211103081231.18578-2-christian.koenig@amd.com

dma-buf: clarify dma_fence_add_callback documentation

That the caller doesn't need to keep a reference is rather
risky and not defensive at all.

Especially dma_buf_poll got that horrible wrong, so better
remove that sentence and also clarify that the callback
might be called in atomic or interrupt context.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210901120240.7339-3-christian.koenig@amd.com

drm/syncobj: use newly allocated stub fences

Allocate a new private stub fence in drm_syncobj_assign_null_handle,
instead of using a static stub fence.

When userspace creates a fence with DRM_SYNCOBJ_CREATE_SIGNALED or when
userspace signals a fence via DRM_IOCTL_SYNCOBJ_SIGNAL, the timestamp
obtained when the fence is exported and queried with SYNC_IOC_FILE_INFO
should match when the fence's status was changed from the perspective of
userspace, which is during the respective ioctl.

When a static stub fence started being used in by these ioctls, this
behavior changed. Instead, the timestamp returned by SYNC_IOC_FILE_INFO
became the first time anything used the static stub fence, which has no
meaning to userspace.

Signed-off-by: David Stevens <stevensd@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210408095428.3983055-1-stevensd@google.com
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-fence: allow signaling drivers to set fence timestamp

Some drivers have hardware capability to get the precise HW timestamp
of certain events based on which the fences are triggered. The delta
between the event HW timestamp & current HW reference timestamp can
be used to calculate the timestamp in kernel's CLOCK_MONOTONIC time
domain. This allows it to set accurate timestamp factoring out any
software and IRQ latencies. Add a timestamp variant of fence signal
function, dma_fence_signal_timestamp to allow drivers to update the
precise timestamp for fences.

Changes in v2:
- Add a new fence signal variant instead of modifying fence struct

Changes in v3:
- Add timestamp domain information to commit-text and
dma_fence_signal_timestamp documentation

Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>
Reviewed-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: minor parenthesis alignment]
Link: https://patchwork.freedesktop.org/patch/msgid/1610757107-11892-1-git-send-email-veeras@codeaurora.org

dma-fence: allow signaling drivers to set fence timestamp

Some drivers have hardware capability to get the precise HW timestamp
of certain events based on which the fences are triggered. The delta
between the event HW timestamp & current HW reference timestamp can
be used to calculate the timestamp in kernel's CLOCK_MONOTONIC time
domain. This allows it to set accurate timestamp factoring out any
software and IRQ latencies. Add a timestamp variant of fence signal
function, dma_fence_signal_timestamp to allow drivers to update the
precise timestamp for fences.

Changes in v2:
- Add a new fence signal variant instead of modifying fence struct

Changes in v3:
- Add timestamp domain information to commit-text and
dma_fence_signal_timestamp documentation

Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>
Reviewed-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: minor parenthesis alignment]
Link: https://patchwork.freedesktop.org/patch/msgid/1610757107-11892-1-git-send-email-veeras@codeaurora.org
(cherry picked from commit 5a164ac4dbd21b82bcdc03186d40e455ff467fdc)
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

dma-buf: fix kernel-doc warning in dma-fence.c

Add @cookie to dma_fence_end_signalling() to prevent kernel-doc
warning in drivers/dma-buf/dma-fence.c:

../drivers/dma-buf/dma-fence.c:291: warning: Function parameter or member 'cookie' not described in 'dma_fence_end_signalling'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/388527/
Signed-off-by: Christian König <christian.koenig@amd.com>

dma-fence: Make symbol 'dma_fence_lockdep_map' static

The sparse tool complains as follows:

drivers/dma-buf/dma-fence.c:249:25: warning:
symbol 'dma_fence_lockdep_map' was not declared. Should it be static?

This variable is not used outside of dma-fence.c, so this commit
marks it static.

Fixes: 5fbff813a4a3 ("dma-fence: basic lockdep annotations")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

Link: https://patchwork.freedesktop.org/patch/msgid/dc5e3b19-2087-44ab-a28c-ddb38ff8861a@email.android.com

dma-fence: prime lockdep annotations

Two in one go:
- it is allowed to call dma_fence_wait() while holding a
dma_resv_lock(). This is fundamental to how eviction works with ttm,
so required.

- it is allowed to call dma_fence_wait() from memory reclaim contexts,
specifically from shrinker callbacks (which i915 does), and from mmu
notifier callbacks (which amdgpu does, and which i915 sometimes also
does, and probably always should, but that's kinda a debate). Also
for stuff like HMM we really need to be able to do this, or things
get real dicey.

Consequence is that any critical path necessary to get to a
dma_fence_signal for a fence must never a) call dma_resv_lock nor b)
allocate memory with GFP_KERNEL. Also by implication of
dma_resv_lock(), no userspace faulting allowed. That's some supremely
obnoxious limitations, which is why we need to sprinkle the right
annotations to all relevant paths.

The one big locking context we're leaving out here is mmu notifiers,
added in

commit 23b68395c7c78a764e8963fc15a7cfd318bf187f
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Aug 26 22:14:21 2019 +0200

mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end

that one covers a lot of other callsites, and it's also allowed to
wait on dma-fences from mmu notifiers. But there's no ready-made
functions exposed to prime this, so I've left it out for now.

v2: Also track against mmu notifier context.

v3: kerneldoc to spec the cross-driver contract. Note that currently
i915 throws in a hard-coded 10s timeout on foreign fences (not sure
why that was done, but it's there), which is why that rule is worded
with SHOULD instead of MUST.

Also some of the mmu_notifier/shrinker rules might surprise SoC
drivers, I haven't fully audited them all. Which is infeasible anyway,
we'll need to run them with lockdep and dma-fence annotations and see
what goes boom.

v4: A spelling fix from Mika

v5: #ifdef for CONFIG_MMU_NOTIFIER. Reported by 0day. Unfortunately
this means lockdep enforcement is slightly inconsistent, it won't spot
GFP_NOIO and GFP_NOFS allocations in the wrong spot if
CONFIG_MMU_NOTIFIER is disabled in the kernel config. Oh well.

v5: Note that only drivers/gpu has a reasonable (or at least
historical) excuse to use dma_fence_wait() from shrinker and mmu
notifier callbacks. Everyone else should either have a better memory
manager model, or better hardware. This reflects discussions with
Jason Gunthorpe.

Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: kernel test robot <lkp@intel.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com> (v4)
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Thomas Hellstrom <thomas.hellstrom@intel.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-rdma@vger.kernel.org
Cc: amd-gfx@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200707201229.472834-3-daniel.vetter@ffwll.ch

dma-fence: basic lockdep annotations

Design is similar to the lockdep annotations for workers, but with
some twists:

- We use a read-lock for the execution/worker/completion side, so that
this explicit annotation can be more liberally sprinkled around.
With read locks lockdep isn't going to complain if the read-side
isn't nested the same way under all circumstances, so ABBA deadlocks
are ok. Which they are, since this is an annotation only.

- We're using non-recursive lockdep read lock mode, since in recursive
read lock mode lockdep does not catch read side hazards. And we
_very_ much want read side hazards to be caught. For full details of
this limitation see

commit e91498589746065e3ae95d9a00b068e525eec34f
Author: Peter Zijlstra <peterz@infradead.org>
Date: Wed Aug 23 13:13:11 2017 +0200

locking/lockdep/selftests: Add mixed read-write ABBA tests

- To allow nesting of the read-side explicit annotations we explicitly
keep track of the nesting. lock_is_held() allows us to do that.

- The wait-side annotation is a write lock, and entirely done within
dma_fence_wait() for everyone by default.

- To be able to freely annotate helper functions I want to make it ok
to call dma_fence_begin/end_signalling from soft/hardirq context.
First attempt was using the hardirq locking context for the write
side in lockdep, but this forces all normal spinlocks nested within
dma_fence_begin/end_signalling to be spinlocks. That bollocks.

The approach now is to simple check in_atomic(), and for these cases
entirely rely on the might_sleep() check in dma_fence_wait(). That
will catch any wrong nesting against spinlocks from soft/hardirq
contexts.

The idea here is that every code path that's critical for eventually
signalling a dma_fence should be annotated with
dma_fence_begin/end_signalling. The annotation ideally starts right
after a dma_fence is published (added to a dma_resv, exposed as a
sync_file fd, attached to a drm_syncobj fd, or anything else that
makes the dma_fence visible to other kernel threads), up to and
including the dma_fence_wait(). Examples are irq handlers, the
scheduler rt threads, the tail of execbuf (after the corresponding
fences are visible), any workers that end up signalling dma_fences and
really anything else. Not annotated should be code paths that only
complete fences opportunistically as the gpu progresses, like e.g.
shrinker/eviction code.

The main class of deadlocks this is supposed to catch are:

Thread A:

mutex_lock(A);
mutex_unlock(A);

dma_fence_signal();

Thread B:

mutex_lock(A);
dma_fence_wait();
mutex_unlock(A);

Thread B is blocked on A signalling the fence, but A never gets around
to that because it cannot acquire the lock A.

Note that dma_fence_wait() is allowed to be nested within
dma_fence_begin/end_signalling sections. To allow this to happen the
read lock needs to be upgraded to a write lock, which means that any
other lock is acquired between the dma_fence_begin_signalling() call and
the call to dma_fence_wait(), and still held, this will result in an
immediate lockdep complaint. The only other option would be to not
annotate such calls, defeating the point. Therefore these annotations
cannot be sprinkled over the code entirely mindless to avoid false
positives.

Originally I hope that the cross-release lockdep extensions would
alleviate the need for explicit annotations:

https://lwn.net/Articles/709849/

But there's a few reasons why that's not an option:

- It's not happening in upstream, since it got reverted due to too
many false positives:

commit e966eaeeb623f09975ef362c2866fae6f86844f9
Author: Ingo Molnar <mingo@kernel.org>
Date: Tue Dec 12 12:31:16 2017 +0100

locking/lockdep: Remove the cross-release locking checks

This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y),
while it found a number of old bugs initially, was also causing too many
false positives that caused people to disable lockdep - which is arguably
a worse overall outcome.

- cross-release uses the complete() call to annotate the end of
critical sections, for dma_fence that would be dma_fence_signal().
But we do not want all dma_fence_signal() calls to be treated as
critical, since many are opportunistic cleanup of gpu requests. If
these get stuck there's still the main completion interrupt and
workers who can unblock everyone. Automatically annotating all
dma_fence_signal() calls would hence cause false positives.

- cross-release had some educated guesses for when a critical section
starts, like fresh syscall or fresh work callback. This would again
cause false positives without explicit annotations, since for
dma_fence the critical sections only starts when we publish a fence.

- Furthermore there can be cases where a thread never does a
dma_fence_signal, but is still critical for reaching completion of
fences. One example would be a scheduler kthread which picks up jobs
and pushes them into hardware, where the interrupt handler or
another completion thread calls dma_fence_signal(). But if the
scheduler thread hangs, then all the fences hang, hence we need to
manually annotate it. cross-release aimed to solve this by chaining
cross-release dependencies, but the dependency from scheduler thread
to the completion interrupt handler goes through hw where
cross-release code can't observe it.

In short, without manual annotations and careful review of the start
and end of critical sections, cross-relese dependency tracking doesn't
work. We need explicit annotations.

v2: handle soft/hardirq ctx better against write side and dont forget
EXPORT_SYMBOL, drivers can't use this otherwise.

v3: Kerneldoc.

v4: Some spelling fixes from Mika

v5: Amend commit message to explain in detail why cross-release isn't
the solution.

v6: Pull out misplaced .rst hunk.

Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Thomas Hellstrom <thomas.hellstrom@intel.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-rdma@vger.kernel.org
Cc: amd-gfx@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200707201229.472834-2-daniel.vetter@ffwll.ch

dma-fence: add might_sleep annotation to _wait()

Do it uncontionally, there's a separate peek function with
dma_fence_is_signalled() which can be called from atomic context.

v2: Consensus calls for an unconditional might_sleep (Chris,
Christian)

Full audit:
- dma-fence.h: Uses MAX_SCHEDULE_TIMOUT, good chance this sleeps
- dma-resv.c: Timeout always at least 1
- st-dma-fence.c: Save to sleep in testcases
- amdgpu_cs.c: Both callers are for variants of the wait ioctl
- amdgpu_device.c: Two callers in vram recover code, both right next
to mutex_lock.
- amdgpu_vm.c: Use in the vm_wait ioctl, next to _reserve/unreserve
- remaining functions in amdgpu: All for test_ib implementations for
various engines, caller for that looks all safe (debugfs, driver
load, reset)
- etnaviv: another wait ioctl
- habanalabs: another wait ioctl
- nouveau_fence.c: hardcoded 15*HZ ... glorious
- nouveau_gem.c: hardcoded 2*HZ ... so not even super consistent, but
this one does have a WARN_ON :-/ At least this one is only a
fallback path for when kmalloc fails. Maybe this should be put onto
some worker list instead, instead of a work per unamp ...
- i915/selftests: Hardecoded HZ / 4 or HZ / 8
- i915/gt/selftests: Going up the callchain looks safe looking at
nearby callers
- i915/gt/intel_gt_requests.c. Wrapped in a mutex_lock
- i915/gem_i915_gem_wait.c: The i915-version which is called instead
for i915 fences already has a might_sleep() annotation, so all good

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: "VMware Graphics" <linux-graphics-maintainer@vmware.com>
Cc: Oded Gabbay <oded.gabbay@gmail.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-rdma@vger.kernel.org
Cc: amd-gfx@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200519132756.682888-1-daniel.vetter@ffwll.ch

dma-buf: Use atomic_fetch_add() for the context id

Now that atomic64_fetch_add() exists we can use it to return the base
context id, rather than the atomic64_add_return(N) - N concoction.

Suggested-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200513074809.18194-2-chris@chris-wilson.co.uk

dma-fence: Serialise signal enabling (dma_fence_enable_sw_signaling)

Make dma_fence_enable_sw_signaling() behave like its
dma_fence_add_callback() and dma_fence_default_wait() counterparts and
perform the test to enable signaling under the fence->lock, along with
the action to do so. This ensure that should an implementation be trying
to flush the cb_list (by signaling) on retirement before freeing the
fence, it can do so in a race-free manner.

See also 0fc89b6802ba ("dma-fence: Simply wrap dma_fence_signal_locked
with dma_fence_signal").

v2: Refactor all 3 enable_signaling paths to use a common function.
v3: Don't argue, just keep the tracepoint in the existing spot.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004101140.32713-1-chris@chris-wilson.co.uk

dma-fence: Store the timestamp in the same union as the cb_list

The timestamp and the cb_list are mutually exclusive, the cb_list can
only be added to prior to being signaled (and once signaled we drain),
while the timestamp is only valid upon being signaled. Both the
timestamp and the cb_list are only valid while the fence is alive, and
as soon as no references are held can be replaced by the rcu_head.

By reusing the union for the timestamp, we squeeze the base dma_fence
struct to 64 bytes on x86-64.

v2: Sort the union chronologically

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>.
Link: https://patchwork.freedesktop.org/patch/msgid/20190817153022.5749-1-chris@chris-wilson.co.uk

dma-fence: Simply wrap dma_fence_signal_locked with dma_fence_signal

Currently dma_fence_signal() tries to avoid the spinlock and only takes
it if absolutely required to walk the callback list. However, to allow
for some users to surreptitiously insert lazy signal callbacks that
do not depend on enabling the signaling mechanism around every fence,
we always need to notify the callbacks on signaling. As such, we will
always need to take the spinlock and dma_fence_signal() effectively
becomes a clone of dma_fence_signal_locked().

v2: Update the test_and_set_bit() before entering the spinlock.
v3: Drop the test_[and_set]_bit() before the spinlock, it's a caller
error so expected to be very unlikely.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christian König <christian.koenig@amd.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190817152300.5370-1-chris@chris-wilson.co.uk

dma-fence: Avoid list_del during fence->cb_list iteration

Before we notify the fence signal callback, we remove the cb from the
list. However, since we are processing the entire list from underneath
the spinlock, we do not need to individual delete each element, but can
simply reset the link and the entire list.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190817144736.7826-4-chris@chris-wilson.co.uk

dma-buf: rename reservation_object to dma_resv

Be more consistent with the naming of the other DMA-buf objects.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/323401/

dma-fence: Signal all callbacks from dma_fence_release()

This is an illegal scenario, to free the fence whilst there are pending
callbacks. Currently, we emit a WARN and then cast aside the callbacks
leaving them dangling. Alternatively, we could set an error on the fence
and then signal fence so that any dependency chains from the fence can
be tidied up, and if they care they can check for the error.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190609110002.31915-1-chris@chris-wilson.co.uk

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 655 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070034.575739538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drm/i915: Seal races between async GPU cancellation, retirement and signaling

Currently there is an underlying assumption that i915_request_unsubmit()
is synchronous wrt the GPU -- that is the request is no longer in flight
as we remove it. In the near future that may change, and this may upset
our signaling as we can process an interrupt for that request while it
is no longer in flight.

CPU0 CPU1
intel_engine_breadcrumbs_irq
(queue request completion)
i915_request_cancel_signaling
... ...
i915_request_enable_signaling
dma_fence_signal

Hence in the time it took us to drop the lock to signal the request, a
preemption event may have occurred and re-queued the request. In the
process, that request would have seen I915_FENCE_FLAG_SIGNAL clear and
so reused the rq->signal_link that was in use on CPU0, leading to bad
pointer chasing in intel_engine_breadcrumbs_irq.

A related issue was that if someone started listening for a signal on a
completed but no longer in-flight request, we missed the opportunity to
immediately signal that request.

Furthermore, as intel_contexts may be immediately released during
request retirement, in order to be entirely sure that
intel_engine_breadcrumbs_irq may no longer dereference the intel_context
(ce->signals and ce->signal_link), we must wait for irq spinlock.

In order to prevent the race, we use a bit in the fence.flags to signal
the transfer onto the signal list inside intel_engine_breadcrumbs_irq.
For simplicity, we use the DMA_FENCE_FLAG_SIGNALED_BIT as it then
quickly signals to any outside observer that the fence is indeed signaled.

v2: Sketch out potential dma-fence API for manual signaling
v3: And the test_and_set_bit()

Fixes: 52c0fdb25c7c ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190508112452.18942-1-chris@chris-wilson.co.uk
(cherry picked from commit 0152b3b3f49b36b0f1a1bf9f0353dc636f41d8f0)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drm/i915: Seal races between async GPU cancellation, retirement and signaling

Currently there is an underlying assumption that i915_request_unsubmit()
is synchronous wrt the GPU -- that is the request is no longer in flight
as we remove it. In the near future that may change, and this may upset
our signaling as we can process an interrupt for that request while it
is no longer in flight.

CPU0 CPU1
intel_engine_breadcrumbs_irq
(queue request completion)
i915_request_cancel_signaling
... ...
i915_request_enable_signaling
dma_fence_signal

Hence in the time it took us to drop the lock to signal the request, a
preemption event may have occurred and re-queued the request. In the
process, that request would have seen I915_FENCE_FLAG_SIGNAL clear and
so reused the rq->signal_link that was in use on CPU0, leading to bad
pointer chasing in intel_engine_breadcrumbs_irq.

A related issue was that if someone started listening for a signal on a
completed but no longer in-flight request, we missed the opportunity to
immediately signal that request.

Furthermore, as intel_contexts may be immediately released during
request retirement, in order to be entirely sure that
intel_engine_breadcrumbs_irq may no longer dereference the intel_context
(ce->signals and ce->signal_link), we must wait for irq spinlock.

In order to prevent the race, we use a bit in the fence.flags to signal
the transfer onto the signal list inside intel_engine_breadcrumbs_irq.
For simplicity, we use the DMA_FENCE_FLAG_SIGNALED_BIT as it then
quickly signals to any outside observer that the fence is indeed signaled.

v2: Sketch out potential dma-fence API for manual signaling
v3: And the test_and_set_bit()

Fixes: 52c0fdb25c7c ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190508112452.18942-1-chris@chris-wilson.co.uk

dma-buf: make fence sequence numbers 64 bit v2

For a lot of use cases we need 64bit sequence numbers. Currently drivers
overload the dma_fence structure to store the additional bits.

Stop doing that and make the sequence number in the dma_fence always
64bit.

For compatibility with hardware which can do only 32bit sequences the
comparisons in __dma_fence_is_later only takes the lower 32bits as significant
when the upper 32bits are all zero.

v2: change the logic in __dma_fence_is_later

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/266927/

dma-buf: add dma_fence_get_stub

Extract of useful code from the timeline work. This provides a function
to return a stub or dummy fence which is always signaled.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/265248/

dma-fence: Polish kernel-doc for dma-fence.c

- Intro section that links to how this is exposed to userspace.
- Lots more hyperlinks.
- Minor clarifications and style polish

v2: Add misplaced hunk of kerneldoc from a different patch.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180704092909.6599-6-daniel.vetter@ffwll.ch

dma-fence: Make ->wait callback optional

Almost everyone uses dma_fence_default_wait.

v2: Also remove the BUG_ON(!ops->wait) (Chris).

Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180503142603.28513-5-daniel.vetter@ffwll.ch

dma-fence: Allow wait_any_timeout for all fences

When this was introduced in

commit a519435a96597d8cd96123246fea4ae5a6c90b02
Author: Christian König <christian.koenig@amd.com>
Date: Tue Oct 20 16:34:16 2015 +0200

dma-buf/fence: add fence_wait_any_timeout function v2

there was a restriction added that this only works if the dma-fence
uses the dma_fence_default_wait hook. Which works for amdgpu, which is
the only caller. Well, until you share some buffers with e.g. i915,
then you get an -EINVAL.

But there's really no reason for this, because all drivers must
support callbacks. The special ->wait hook is only as an optimization;
if the driver needs to create a worker thread for an active callback,
then it can avoid to do that if it knows that there's a process
context available already. So ->wait is just an optimization, just
using the logic in dma_fence_default_wait() should work for all
drivers.

Let's remove this restriction.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180503142603.28513-4-daniel.vetter@ffwll.ch

dma-fence: Make ->enable_signaling optional

Many drivers have a trivial implementation for ->enable_signaling.
Let's make it optional by assuming that signalling is already
available when the callback isn't present.

v2: Don't do the trick to set the ENABLE_SIGNAL_BIT
unconditionally, it results in an expensive spinlock take for
everyone. Instead just check if the callback is present. Suggested by
Maarten.

Also move misplaced kerneldoc hunk to the right patch.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180504141034.27727-1-daniel.vetter@ffwll.ch

Revert 190c462d5be19ba622a82f5fd0625087c870a1e6..bf3012ada1b2222e770de5c35c1bb16f73b3a01d"

I shouldn't have pushed this, CI was right - I failed to remove the
BUG_ON(!ops->wait);

Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

dma-fence: Make ->wait callback optional

Almost everyone uses dma_fence_default_wait.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-6-daniel.vetter@ffwll.ch

dma-fence: Allow wait_any_timeout for all fences

When this was introduced in

commit a519435a96597d8cd96123246fea4ae5a6c90b02
Author: Christian König <christian.koenig@amd.com>
Date: Tue Oct 20 16:34:16 2015 +0200

dma-buf/fence: add fence_wait_any_timeout function v2

there was a restriction added that this only works if the dma-fence
uses the dma_fence_default_wait hook. Which works for amdgpu, which is
the only caller. Well, until you share some buffers with e.g. i915,
then you get an -EINVAL.

But there's really no reason for this, because all drivers must
support callbacks. The special ->wait hook is only as an optimization;
if the driver needs to create a worker thread for an active callback,
then it can avoid to do that if it knows that there's a process
context available already. So ->wait is just an optimization, just
using the logic in dma_fence_default_wait() should work for all
drivers.

Let's remove this restriction.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-5-daniel.vetter@ffwll.ch

dma-fence: Make ->enable_signaling optional

Many drivers have a trivial implementation for ->enable_signaling.
Let's make it optional by assuming that signalling is already
available when the callback isn't present.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-4-daniel.vetter@ffwll.ch

dma-fence: add comment for WARN_ON in dma_fence_release()

In dma_fence_release() there is a WARN_ON which could be triggered by
several cases of wrong dma-fence usage. This patch adds a comment to
explain two use-cases to help driver developers that use dma-fence
and trigger that WARN_ON to better understand the reasons for it.

v2: change to a more generic, one-liner comment

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

tracing, dma-buf: Remove unused trace event dma_fence_annotate_wait_on

Commit e941759c74 ("fence: dma-buf cross-device synchronization") added
trace event fence_annotate_wait_on, but never used it. It was renamed
to dma_fence_annotate_wait_on by commit f54d186700 ("dma-buf: Rename
struct fence to dma_fence") but still not used. As defined trace events
have data structures and functions created for them, it is a waste of
memory if they are not used. Remove the unused trace event.

Link: http://lkml.kernel.org/r/20171013100625.6c820059@gandalf.local.home

Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

dma-fence: Don't BUG_ON when not absolutely needed

It makes debugging a massive pain.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170720125107.26693-1-daniel.vetter@ffwll.ch
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

dma-buf/fence: Avoid use of uninitialised timestamp

[ 236.821534] WARNING: kmemcheck: Caught 64-bit read from uninitialized memory (ffff8802538683d0)
[ 236.828642] 420000001e7f0000000000000000000000080000000000000000000000000000
[ 236.839543] i i i i u u u u i i i i i i i i u u u u u u u u u u u u u u u u
[ 236.850420] ^
[ 236.854123] RIP: 0010:[<ffffffff81396f07>] [<ffffffff81396f07>] fence_signal+0x17/0xd0
[ 236.861313] RSP: 0018:ffff88024acd7ba0 EFLAGS: 00010282
[ 236.865027] RAX: ffffffff812f6a90 RBX: ffff8802527ca800 RCX: ffff880252cb30e0
[ 236.868801] RDX: ffff88024ac5d918 RSI: ffff880252f780e0 RDI: ffff880253868380
[ 236.872579] RBP: ffff88024acd7bc0 R08: ffff88024acd7be0 R09: 0000000000000000
[ 236.876407] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880253868380
[ 236.880185] R13: ffff8802538684d0 R14: ffff880253868380 R15: ffff88024cd48e00
[ 236.883983] FS: 00007f1646d1a740(0000) GS:ffff88025d000000(0000) knlGS:0000000000000000
[ 236.890959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 236.894702] CR2: ffff880251360318 CR3: 000000024ad21000 CR4: 00000000001406f0
[ 236.898481] [<ffffffff8130d1ad>] i915_gem_request_retire+0x1cd/0x230
[ 236.902439] [<ffffffff8130e2b3>] i915_gem_request_alloc+0xa3/0x2f0
[ 236.906435] [<ffffffff812fb1bd>] i915_gem_do_execbuffer.isra.41+0xb6d/0x18b0
[ 236.910434] [<ffffffff812fc265>] i915_gem_execbuffer2+0x95/0x1e0
[ 236.914390] [<ffffffff812ad625>] drm_ioctl+0x1e5/0x460
[ 236.918275] [<ffffffff8110d4cf>] do_vfs_ioctl+0x8f/0x5c0
[ 236.922168] [<ffffffff8110da3c>] SyS_ioctl+0x3c/0x70
[ 236.926090] [<ffffffff814b7a5f>] entry_SYSCALL_64_fastpath+0x17/0x93
[ 236.930045] [<ffffffffffffffff>] 0xffffffffffffffff

We only set the timestamp before we mark the fence as signaled. It is
done before to avoid observers having a window in which they may see the
fence as complete but no timestamp. Having it does incur a potential for
the timestamp to be written twice, and even for it to be corrupted if
the u64 write is not atomic. Instead use a new bit to record the
presence of the timestamp, and teach the readers to wait until it is set
if the fence is complete. There still remains a race where the timestamp
for the signaled fence may be shown before the fence is reported as
signaled, but that's a pre-existing error.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Reported-by: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170214124001.1930-1-chris@chris-wilson.co.uk

dma-buf: avoid scheduling on fence status query v2

When a timeout of zero is specified, the caller is only interested in
the fence status.

In the current implementation, dma_fence_default_wait will always call
schedule_timeout() at least once for an unsignaled fence. This adds a
significant overhead to a fence status query.

Avoid this overhead by returning early if a zero timeout is specified.

v2: move early return after enable_signaling

Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170426144620.3560-1-andresx7@gmail.com

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

dma-buf/dma-fence: improve doc for dma_fence_add_callback()

Document return values for this function.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170215175725.6692-1-gustavo@padovan.org

dma/fence: Export enable-signaling tracepoint for emission by drivers

Currently this tracepoint is solely used by dma_fence_enable_sw_signaling,
however I have a need to manually perform the hw enabling of the
signaling and would like to emit this tracepoint for completeness.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124115758.31353-1-chris@chris-wilson.co.uk

dma-fence: Introduce drm_fence_set_error() helper

The dma_fence.error field (formerly known as dma_fence.status) is an
optional field that may be set by drivers before calling
dma_fence_signal(). The field can be used to indicate that the fence was
completed in err rather than with success, and is visible to other
consumers of the fence and to userspace via sync_file.

This patch renames the field from status to error so that its meaning is
hopefully more clear (and distinct from dma_fence_get_status() which is
a composite between the error state and signal state) and adds a helper
that validates the preconditions of when it is suitable to adjust the
error field.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-3-chris@chris-wilson.co.uk

dma-fence: Wrap querying the fence->status

The fence->status is an optional field that is only valid once the fence
has been signaled. (Driver may fill the fence->status with an error code
prior to calling dma_fence_signal().) Given the restriction upon its
validity, wrap querying of the fence->status into a helper
dma_fence_get_status().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-2-chris@chris-wilson.co.uk

dma-fence: Clear fence->status during dma_fence_init()

As the fence->status is an optional field that may be set before
dma_fence_signal() is called to convey that the fence completed with an
error, we have to ensure that it is always set to zero on initialisation
so that the typical use (i.e. unset) always flags a successful completion.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-1-chris@chris-wilson.co.uk

dma-buf/fence: revert "don't wait when specified timeout is zero" (v2)

Reverts commit 847b19a39e4c
("dma-buf/fence: don't wait when specified timeout is zero")

When we don't call the wait function software signaling might never be
activated. This can cause infinite polling loops with unreliable interrupt
driven hardware.

v2: rebase on drm-next

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: reword commit msg for checkpatch warnings]
Link: http://patchwork.freedesktop.org/patch/msgid/1478553376-18575-2-git-send-email-alexander.deucher@amd.com

dma-buf/fence: make timeout handling in fence_default_wait consistent (v2)

Kernel functions taking a timeout usually return 1 on success even
when they get a zero timeout.

v2: agd: rebase on drm-next

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1478553376-18575-1-git-send-email-alexander.deucher@amd.com

dma-buf: return index of the first signaled fence (v2)

Return the index of the first signaled fence. This information
is useful in some APIs like Vulkan.

v2: rebase on drm-next (fence -> dma_fence)

Signed-off-by: monk.liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: fix warnings]
Link: http://patchwork.freedesktop.org/patch/msgid/1478290570-30982-1-git-send-email-alexander.deucher@amd.com

dma-buf: Rename struct fence to dma_fence

I plan to usurp the short name of struct fence for a core kernel struct,
and so I need to rename the specialised fence/timeline for DMA
operations to make room.

A consensus was reached in
https://lists.freedesktop.org/archives/dri-devel/2016-July/113083.html
that making clear this fence applies to DMA operations was a good thing.
Since then the patch has grown a bit as usage increases, so hopefully it
remains a good thing!

(v2...: rebase, rerun spatch)
v3: Compile on msm, spotted a manual fixup that I broke.
v4: Try again for msm, sorry Daniel

coccinelle script:
@@

@@
- struct fence
+ struct dma_fence
@@

@@
- struct fence_ops
+ struct dma_fence_ops
@@

@@
- struct fence_cb
+ struct dma_fence_cb
@@

@@
- struct fence_array
+ struct dma_fence_array
@@

@@
- enum fence_flag_bits
+ enum dma_fence_flag_bits
@@

@@
(
- fence_init
+ dma_fence_init
|
- fence_release
+ dma_fence_release
|
- fence_free
+ dma_fence_free
|
- fence_get
+ dma_fence_get
|
- fence_get_rcu
+ dma_fence_get_rcu
|
- fence_put
+ dma_fence_put
|
- fence_signal
+ dma_fence_signal
|
- fence_signal_locked
+ dma_fence_signal_locked
|
- fence_default_wait
+ dma_fence_default_wait
|
- fence_add_callback
+ dma_fence_add_callback
|
- fence_remove_callback
+ dma_fence_remove_callback
|
- fence_enable_sw_signaling
+ dma_fence_enable_sw_signaling
|
- fence_is_signaled_locked
+ dma_fence_is_signaled_locked
|
- fence_is_signaled
+ dma_fence_is_signaled
|
- fence_is_later
+ dma_fence_is_later
|
- fence_later
+ dma_fence_later
|
- fence_wait_timeout
+ dma_fence_wait_timeout
|
- fence_wait_any_timeout
+ dma_fence_wait_any_timeout
|
- fence_wait
+ dma_fence_wait
|
- fence_context_alloc
+ dma_fence_context_alloc
|
- fence_array_create
+ dma_fence_array_create
|
- to_fence_array
+ to_dma_fence_array
|
- fence_is_array
+ dma_fence_is_array
|
- trace_fence_emit
+ trace_dma_fence_emit
|
- FENCE_TRACE
+ DMA_FENCE_TRACE
|
- FENCE_WARN
+ DMA_FENCE_WARN
|
- FENCE_ERR
+ DMA_FENCE_ERR
)
(
...
)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161025120045.28839-1-chris@chris-wilson.co.uk