Prevent application hangs caused by out-of-order fence signaling when
user fences are attached. Use drm_syncobj (via dma-fence-chain) to
guarantee that each user fence signals in order, regardless of the
signaling order of the attached fences. Ensure user fence writebacks to
user space occur in the correct sequence.
v7:
- Skip drm_syncbj create of error (CI)
Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251031234050.3043507-2-matthew.brost@intel.com
(cherry picked from commit adda4e855a)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Add support for attaching the last fence to TLB invalidation job queues
to address serialization issues during bursts of unbind jobs. Ensure
that user fence signaling for a bind job reflects both the bind job
itself and the last fences of all related TLB invalidations. Maintain
submission order based solely on the state of the bind and TLB
invalidation queues.
Introduce support functions for last fence attachment to TLB
invalidation queues.
v3:
- Fix assert in xe_exec_queue_tlb_inval_last_fence_set (CI)
- Ensure migrate lock held for migrate queues (Testing)
v5:
- Style nits (Thomas)
- Rewrite commit message (Thomas)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251031234050.3043507-3-matthew.brost@intel.com
Prevent application hangs caused by out-of-order fence signaling when
user fences are attached. Use drm_syncobj (via dma-fence-chain) to
guarantee that each user fence signals in order, regardless of the
signaling order of the attached fences. Ensure user fence writebacks to
user space occur in the correct sequence.
v7:
- Skip drm_syncbj create of error (CI)
Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251031234050.3043507-2-matthew.brost@intel.com
Add a limit to the number of jobs that can be queued in a single
exec queue to avoid potential resource exhaustion.
A new field `job_cnt` is introduced in `struct xe_exec_queue` to
track the number of active DRM jobs, along with a maximum limit
`XE_MAX_JOB_COUNT_PER_EXEC_QUEUE` set to 1000.
If the job count exceeds this threshold, `xe_exec_ioctl()` now
returns `-EAGAIN` to signal that the caller should retry later.
A trace event is added to track when the limit is reached:
"xe_exec_queue_reach_max_job_count: dev=0000:03:00.0, job count
exceeded the maximum limit (1000) per exec queue. engine_class=0x3,
logical_mask=0x1, guc_id=2"
v3: add assert in xe_exec_queue_destroy that q->job_cnt is zero. (Matt)
v2 (Matt):
- add log to trace the limit is hit.
- Change max count from 0x1000 to 1000.
- Use atomic_t for job_cnt.
Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251027202118.3339905-2-shuicheng.lin@intel.com
A queue must be in the submission backend's tracking state before the
LRC is created to avoid a race condition where the LRC's GGTT addresses
are not properly fixed up during VF post-migration recovery.
Move the queue initialization—which adds the queue to the submission
backend's tracking state—before LRC creation.
Also wait on pending GGTT fixups before allocating LRCs to avoid racing
with fixups.
v2:
- Wait on VF GGTT fixes before creating LRC (testing)
v5:
- Adjust comment in code (Tomasz)
- Reduce race window
v7:
- Only wakeup waiters in recovery path (CI)
- Wakeup waiters on abort
- Use GT warn on (Michal)
- Fix kernel doc for LRC ring size function (Tomasz)
v8:
- Guard against migration not supported or no memirq (CI)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: https://lore.kernel.org/r/20251008214532.3442967-28-matthew.brost@intel.com
VF migration requires jobs to remain pending so they can be replayed
after the VF comes back. Previously, LR job fences were intentionally
signaled immediately after submission to avoid the risk of exporting
them, as these fences do not naturally signal in a timely manner and
could break dma-fence contracts. A side effect of this approach was that
LR jobs were never added to the DRM scheduler’s pending list, preventing
them from being tracked for later resubmission.
We now avoid signaling LR job fences and ensure they are never exported;
Xe already guards against exporting these internal fences. With that
guarantee in place, we can safely track LR jobs in the scheduler’s
pending list so they are eligible for resubmission during VF
post-migration recovery (and similar recovery paths).
An added benefit is that LR queues now gain the DRM scheduler’s built-in
flow control over ring usage rather than rejecting new jobs in the exec
IOCTL if the ring is full.
v2:
- Ensure DRM scheduler TDR doesn't run for LR jobs
- Stack variable for killed_or_banned_or_wedged
v4:
- Clarify commit message (Tomasz)
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Tomasz Lis <tomasz.lis@intel.com>
Link: https://lore.kernel.org/r/20251008214532.3442967-5-matthew.brost@intel.com
Since the PXP start comes after __xe_exec_queue_init() has completed,
we need to cleanup what was done in that function in case of a PXP
start error.
__xe_exec_queue_init calls the submission backend init() function,
so we need to introduce an opposite for that. Unfortunately, while
we already have a fini() function pointer, it performs other
operations in addition to cleaning up what was done by the init().
Therefore, for clarity, the existing fini() has been renamed to
destroy(), while a new fini() has been added to only clean up what was
done by the init(), with the latter being called by the former (via
xe_exec_queue_fini).
Fixes: 72d479601d ("drm/xe/pxp/uapi: Add userspace and LRC support for PXP-using queues")
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://lore.kernel.org/r/20250909221240.3711023-3-daniele.ceraolospurio@intel.com
The WA buffer we use to capture context utilization contains GGTT
references. This means its instructions have to be either fixed or
re-emitted during VF post-migration recovery.
This patch adds re-emitting content of the utilization WA BB during
the recovery.
The way we write to vram requires scratch buffer to be used before
the whole block is memcopied. We are re-using a scratch buffer
introduced in earlier part of the recovery. This is not a performance
optimization, but a necessity to avoid creating dependencies between
locks.
v2: Notable rebase after "Prepare WA BB setup for more users" patch
v3: Added error propagation
Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Reviewed-by: Michal Winiarski <michal.winiarski@intel.com>
Link: https://lore.kernel.org/r/20250802031045.1127138-8-tomasz.lis@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
All contexts require an update of state data, as the data includes
GGTT references to memirq-related buffers.
Default contexts need these references updated as well, because they
are not refreshed when a new context is created from them.
The way we write to vram requires scratch buffer to be used
before the whole block is memcopied. Since using kalloc() within
specific recovery functions would lead to unintended relations
between locks, we are allocating the buffer earlier, before
any locks are taken. The same buffer will be used for other steps
of the recovery.
v2: Update addresses by xe_lrc_write_ctx_reg() rather than
set_memory_based_intr()
v3: Renamed parameter, reordered parameters in some functs
v4: Check if have MEMIRQ, move `xe_gt*` funct to proper file
v5: Revert back to requiring scratch buffer, but allocate it
earlier this time
Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Acked-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Reviewed-by: Michal Winiarski <michal.winiarski@intel.com>
Link: https://lore.kernel.org/r/20250802031045.1127138-6-tomasz.lis@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
On current platforms with multiple GTs, all of the GT IDs are
consecutive; as a result we know that the GT IDs range from 0 to
gt_count-1 and can determine if a GT ID is valid by comparing against
the count. The consecutive nature of GT IDs may not hold true on future
platforms if/when we have platforms that are both multi-tile and have
multiple GTs within each tile. Once such platforms exist, it's quite
possible that we could wind up with something like a GT list composed of
IDs 0, 2, and 3 with no GT 1 (which would be a 2-tile platform with
media only on the second tile).
To future-proof the code we should stop comparing against the GT count
to determine whether a GT ID is valid or not. Instead we should do an
actual lookup of the ID to determine whether the GT exists. This also
means that our GT loop macro should not end at the GT count, but should
rather examine the entire space up to (# of tiles) * (max GT per tile)
to ensure it doesn't stop prematurely.
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://lore.kernel.org/r/20250701201320.2514369-15-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Context Timestamp (CTX_TIMESTAMP) in the LRC accumulates the run ticks
of the context, but only gets updated when the context switches out. In
order to check how long a context has been active before it switches
out, two things are required:
(1) Determine if the context is running:
To do so, we program the WA BB to set an initial value for CTX_TIMESTAMP
in the LRC. The value chosen is 1 since 0 is the initial value when the
LRC is initialized. During a query, we just check for this value to
determine if the context is active. If the context switched out, it
would overwrite this location with the actual CTX_TIMESTAMP MMIO value.
Note that WA BB runs as the last part of the context restore, so reusing
this LRC location will not clobber anything.
(2) Calculate the time that the context has been active for:
The CTX_TIMESTAMP ticks only when the context is active. If a context is
active, we just use the CTX_TIMESTAMP MMIO as the new value of
utilization. While doing so, we need to read the CTX_TIMESTAMP MMIO
for the specific engine instance. Since we do not know which instance
the context is running on until it is scheduled, we also read the
ENGINE_ID MMIO in the WA BB and store it in the PPHSWP.
Using the above 2 instructions in a WA BB, capture active context
utilization.
v2: (Matt Brost)
- This breaks TDR, fix it by saving the CTX_TIMESTAMP register
"drm/xe: Save CTX_TIMESTAMP mmio value instead of LRC value"
- Drop tile from LRC if using gt
"drm/xe: Save the gt pointer in LRC and drop the tile"
v3:
- Remove helpers for bb_per_ctx_ptr (Matt)
- Add define for context active value (Matt)
- Use 64 bit CTX TIMESTAMP for platforms that support it. For platforms
that don't, live with the rare race. (Matt, Lucas)
- Convert engine id to hwe and get the MMIO value (Lucas)
- Correct commit message on when WA BB runs (Lucas)
v4:
- s/GRAPHICS_VER(...)/xe->info.has_64bit_timestamp/ (Matt)
- Drop support for active utilization on a VF (CI failure)
- In xe_lrc_init ensure the lrc value is 0 to begin with (CI regression)
v5:
- Minor checkpatch fix
- Squash into previous commit and make TDR use 32-bit time
- Update code comment to match commit msg
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4532
Suggested-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250509161159.2173069-8-umesh.nerlige.ramappa@intel.com
Use fault injection infrastructure to allow specific functions to
be configured over debugfs for failing during the execution of
xe_exec_queue_create_ioctl(). xe_exec_queue_destroy_ioctl() and
xe_exec_queue_get_property_ioctl() are not considered as there is
no unwinding code to test with fault injection.
This allows more thorough testing from user space by going through
code paths for error handling and unwinding which cannot be reached
by simply injecting errors in IOCTL arguments. This can help
increase code robustness.
The corresponding IGT series is:
https://patchwork.freedesktop.org/series/144138/
Reviewed-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250305150659.46276-1-francois.dugast@intel.com
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Allow user to provide a low latency hint. When set, KMD sends a hint
to GuC which results in special handling for that process. SLPC will
ramp the GT frequency aggressively every time it switches to this
process.
We need to enable the use of SLPC Compute strategy during init, but
it will apply only to processes that set this bit during process
creation.
Improvement with this approach as below:
Before,
:~$ NEOReadDebugKeys=1 EnableDirectSubmission=0 clpeak --kernel-latency
Platform: Intel(R) OpenCL Graphics
Device: Intel(R) Graphics [0xe20b]
Driver version : 24.52.0 (Linux x64)
Compute units : 160
Clock frequency : 2850 MHz
Kernel launch latency : 283.16 us
After,
:~$ NEOReadDebugKeys=1 EnableDirectSubmission=0 clpeak --kernel-latency
Platform: Intel(R) OpenCL Graphics
Device: Intel(R) Graphics [0xe20b]
Driver version : 24.52.0 (Linux x64)
Compute units : 160
Clock frequency : 2850 MHz
Kernel launch latency : 63.38 us
Compute PR: https://github.com/intel/compute-runtime/pull/794
Mesa PR: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33214
IGT PR: https://patchwork.freedesktop.org/patch/639989/
V10(Lucas):
- Remove doc from drm-uapi.rst
v9(Vinay):
- remove extra line, align commit message
v8(Vinay):
- Add separate example for using low latency hint
v7(Jose):
- Update UMD PR
- applicable to all gpus
V6:
- init flags, remove redundant flags check (MAuld)
V5:
- Move uapi doc to documentation and GuC ABI specific change (Rodrigo)
- Modify logic to restrict exec queue flags (MAuld)
V4:
- To make it clear, dont use exec queue word (Vinay)
- Correct typo in description of flag (Jose/Vinay)
- rename set_strategy api and replace ctx with exec queue(Vinay)
- Start with 0th bit to indentify user flags (Jose)
V3:
- Conver user flag to kernel internal flag and use (Oak)
- Support query config for use to check kernel support (Jose)
- Dont need to take runtime pm (Vinay)
V2:
- DRM_XE_EXEC_QUEUE_LOW_LATENCY_HINT 1 planned for other hint(Szymon)
- Add motivation to description (Lucas)
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250228070224.739295-2-tejas.upadhyay@intel.com
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Userspace is required to mark a queue as using PXP to guarantee that the
PXP instructions will work. In addition to managing the PXP sessions,
when a PXP queue is created the driver will set the relevant bits in
its context control register.
On submission of a valid PXP queue, the driver will validate all
encrypted objects mapped to the VM to ensured they were encrypted with
the current key.
v2: Remove pxp_types include outside of PXP code (Jani), better comments
and code cleanup (John)
v3: split the internal PXP management to a separate patch for ease of
review. re-order ioctl checks to always return -EINVAL if parameters are
invalid, rebase on msix changes.
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-9-daniele.ceraolospurio@intel.com
We expect every queue that uses PXP to be marked as doing so, to allow
the driver to correctly manage the encryption status. The API for doing
this from userspace is coming in the next patch, while this patch
implement the management side of things. When a PXP queue is created,
the driver will do the following:
- Start the default PXP session if it is not already running;
- assign an rpm ref to the queue to keep for its lifetime (this is
required because PXP HWDRM sessions are killed by the HW suspend flow).
Since PXP start and termination can race each other, this patch also
introduces locking and a state machine to keep track of the pending
operations. Note that since we'll need to take the lock from the
suspend/resume paths as well, we can't do submissions while holding it,
which means we need a slightly more complicated state machine to keep
track of intermediate steps.
v4: new patch in the series, split from the following interface patch to
keep review manageable. Lock and status rework to not do submissions
under lock.
v5: Improve comments and error logs (John)
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-8-daniele.ceraolospurio@intel.com
PXP requires submissions to the HW for the following operations
1) Key invalidation, done via the VCS engine
2) Communication with the GSC FW for session management, done via the
GSCCS.
Key invalidation submissions are serialized (only 1 termination can be
serviced at a given time) and done via GGTT, so we can allocate a simple
BO and a kernel queue for it.
Submissions for session management are tied to a PXP client (identified
by a unique host_session_id); from the GSC POV this is a user-accessible
construct, so all related submission must be done via PPGTT. The driver
does not currently support PPGTT submission from within the kernel, so
to add this support, the following changes have been included:
- a new type of kernel-owned VM (marked as GSC), required to ensure we
don't use fault mode on the engine and to mark the different lock
usage with lockdep.
- a new function to map a BO into a VM from within the kernel.
v2: improve comments and function name, remove unneeded include (John)
v3: fix variable/function names in documentation
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-3-daniele.ceraolospurio@intel.com
Use fault injection infrastructure to allow specific functions to
be configured over debugfs for failing during the execution of
xe_vm_create_ioctl() and xe_vm_bind_ioctl(). This allows more
thorough testing from user space by going through code paths for
error handling and unwinding which cannot be reached by simply
injecting errors in IOCTL arguments. This can help increase code
robustness.
v2: Add xe_pt_update_ops_{prepare,run} (Matthew Brost)
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241113162212.2154103-1-francois.dugast@intel.com
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
When an exec queue is killed it triggers an async process of asking the
GuC to schedule the context out. The timestamp in the context image is
only updated when this process completes. In case a userspace process
kills an exec and tries to read the timestamp, it may not get an updated
runtime.
Add synchronization between the process reading the fdinfo and the exec
queue being killed. After reading all the timestamps, wait on exec
queues in the process of being killed. When that wait is over,
xe_exec_queue_fini() was already called and updated the timestamps.
v2: Do not update pending_removal before validating user args
(Matthew Auld)
v3: Move wait on pending to be done before getting any timestamp
so it's more likely for the gpu and exec queue timestamps to
be closer together
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2667
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241108053318.3483678-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
The exec queue timestamp is only really useful when it's being queried
through the fdinfo. There's no need to update it so often, on every
job_free. Tracing a simple app like vkcube running shows an update
rate of ~ 120Hz. In case of discrete, the BO is on vram, creating a lot
of pcie transactions.
The update on job_free() is used to cover a gap: if exec
queue is created and destroyed rapidly, before a new query, the
timestamp still needs to be accumulated and accounted for in the xef.
Initial implementation in commit 6109f24f87 ("drm/xe: Add helper to
accumulate exec queue runtime") couldn't do it on the exec_queue_fini
since the xef could be gone at that point. However since commit
ce8c161cba ("drm/xe: Add ref counting for xe_file") the xef is
refcounted and the exec queue always holds a reference, making this safe
now.
Improve the fix in commit 2149ded630 ("drm/xe: Fix use after free when
client stats are captured") by reducing the frequency in which the
update is needed.
Fixes: 2149ded630 ("drm/xe: Fix use after free when client stats are captured")
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241104143815.2112272-3-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
(cherry picked from commit 83db047d94)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
The exec queue timestamp is only really useful when it's being queried
through the fdinfo. There's no need to update it so often, on every
job_free. Tracing a simple app like vkcube running shows an update
rate of ~ 120Hz. In case of discrete, the BO is on vram, creating a lot
of pcie transactions.
The update on job_free() is used to cover a gap: if exec
queue is created and destroyed rapidly, before a new query, the
timestamp still needs to be accumulated and accounted for in the xef.
Initial implementation in commit 6109f24f87 ("drm/xe: Add helper to
accumulate exec queue runtime") couldn't do it on the exec_queue_fini
since the xef could be gone at that point. However since commit
ce8c161cba ("drm/xe: Add ref counting for xe_file") the xef is
refcounted and the exec queue always holds a reference, making this safe
now.
Improve the fix in commit 2149ded630 ("drm/xe: Fix use after free when
client stats are captured") by reducing the frequency in which the
update is needed.
Fixes: 2149ded630 ("drm/xe: Fix use after free when client stats are captured")
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241104143815.2112272-3-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Both the VM / exec queue file lock protect the lookup and reference to
the object, nothing more. These locks are not intended anything else
underneath them. XA have their own locking too, so no need to take the
VM / exec queue file lock aside from when doing a lookup and reference
get.
Add some kernel doc to make this clear and cleanup a few typos too.
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240921011712.2681510-1-matthew.brost@intel.com
Ensure we can safely take a ref of the exec queue's last fence from the
context of resuming jobs from the hw engine group. The locking requirements
differ from the general case, hence the introduction of this new function.
v2: Add kernel doc, rework the code to prevent code duplication
v3: Fix kernel doc, remove now unnecessary lockdep variants (Matt Brost)
v4: Remove new put function (Matt Brost)
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240809155156.1955925-7-francois.dugast@intel.com
