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drm/i915/guc: Consider also RCU depth in busy loop.

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BugLink: https://bugs.launchpad.net/bugs/2060704

intel_guc_send_busy_loop() looks at in_atomic() and irqs_disabled() to
decide if it should busy-spin while waiting or if it may sleep.
Both checks will report false on PREEMPT_RT if sleeping spinlocks are
acquired leading to RCU splats while the function sleeps.

Check also if RCU has been disabled.

Reported-by: "John B. Wyatt IV" <jwyatt@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Kevin Becker <kevin.becker@canonical.com>
This commit is contained in:
Sebastian Andrzej Siewior
2023-10-03 21:37:21 +02:00
committed by Kevin Becker
parent 166c33a748
commit 6ad794652c
1 changed files with 1 additions and 1 deletions
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drivers/gpu/drm/i915/gt/uc/intel_guc.h
+1 -1
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@@ -364,7 +364,7 @@ static inline int intel_guc_send_busy_loop(struct intel_guc *guc,
{
int err;
unsigned int sleep_period_ms = 1;
bool not_atomic = !in_atomic() && !irqs_disabled();
bool not_atomic = !in_atomic() && !irqs_disabled() && !rcu_preempt_depth();
/*
* FIXME: Have caller pass in if we are in an atomic context to avoid