We rely on only the tasklet being allowed to call into process_csb(), so
assert that is locked when we do. As the tasklet uses a simple bitlock,
there is no strong lockdep checking so we must make do with a plain
assertion that the tasklet is running and assume that we are the
tasklet!
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 1 +
drivers/gpu/drm/i915/i915_gem.h | 5 +++++
2 files changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 8be9e69d5718..ab20433182d1 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1984,6 +1984,7 @@ static void process_csb(struct intel_engine_cs *engine)
u8 head, tail;
GEM_BUG_ON(USES_GUC_SUBMISSION(engine->i915));
+ GEM_BUG_ON(!tasklet_is_locked(&execlists->tasklet));
/*
* Note that csb_write, csb_status may be either in HWSP or mmio.
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index db20d2b0842b..f6f9675848b8 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -86,6 +86,11 @@ static inline void tasklet_lock(struct tasklet_struct *t)
cpu_relax();
}
+static inline bool tasklet_is_locked(const struct tasklet_struct *t)
+{
+ return test_bit(TASKLET_STATE_RUN, &t->state);
+}
+
static inline void __tasklet_disable_sync_once(struct tasklet_struct *t)
{
if (!atomic_fetch_inc(&t->count))
--
2.23.0
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