drm/i915: Defer semaphore priority bumping to a workqueue
Since the semaphore fence may be signaled from inside an interrupt
handler from inside a request holding its request->lock, we cannot then
enter into the engine->active.lock for processing the semaphore priority
bump as we may traverse our call tree and end up on another held
request.
CPU 0:
[ 2243.218864] _raw_spin_lock_irqsave+0x9a/0xb0
[ 2243.218867] i915_schedule_bump_priority+0x49/0x80 [i915]
[ 2243.218869] semaphore_notify+0x6d/0x98 [i915]
[ 2243.218871] __i915_sw_fence_complete+0x61/0x420 [i915]
[ 2243.218874] ? kmem_cache_free+0x211/0x290
[ 2243.218876] i915_sw_fence_complete+0x58/0x80 [i915]
[ 2243.218879] dma_i915_sw_fence_wake+0x3e/0x80 [i915]
[ 2243.218881] signal_irq_work+0x571/0x690 [i915]
[ 2243.218883] irq_work_run_list+0xd7/0x120
[ 2243.218885] irq_work_run+0x1d/0x50
[ 2243.218887] smp_irq_work_interrupt+0x21/0x30
[ 2243.218889] irq_work_interrupt+0xf/0x20
CPU 1:
[ 2242.173107] _raw_spin_lock+0x8f/0xa0
[ 2242.173110] __i915_request_submit+0x64/0x4a0 [i915]
[ 2242.173112] __execlists_submission_tasklet+0x8ee/0x2120 [i915]
[ 2242.173114] ? i915_sched_lookup_priolist+0x1e3/0x2b0 [i915]
[ 2242.173117] execlists_submit_request+0x2e8/0x2f0 [i915]
[ 2242.173119] submit_notify+0x8f/0xc0 [i915]
[ 2242.173121] __i915_sw_fence_complete+0x61/0x420 [i915]
[ 2242.173124] ? _raw_spin_unlock_irqrestore+0x39/0x40
[ 2242.173137] i915_sw_fence_complete+0x58/0x80 [i915]
[ 2242.173140] i915_sw_fence_commit+0x16/0x20 [i915]
Closes: https://gitlab.freedesktop.org/drm/intel/issues/1318
Fixes: b7404c7ecb38 ("drm/i915: Bump ready tasks ahead of busywaits")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200310101720.9944-1-chris@chris-wilson.co.uk
(cherry picked from commit 209df10bb4536c81c2540df96c02cd079435357f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2 files changed
