31 lines
1.2 KiB
Diff
31 lines
1.2 KiB
Diff
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Tue, 3 Oct 2023 21:37:21 +0200
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Subject: [PATCH 7/8] drm/i915/guc: Consider also RCU depth in busy loop.
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.11/older/patches-6.11-rt7.tar.xz
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intel_guc_send_busy_loop() looks at in_atomic() and irqs_disabled() to
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decide if it should busy-spin while waiting or if it may sleep.
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Both checks will report false on PREEMPT_RT if sleeping spinlocks are
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acquired leading to RCU splats while the function sleeps.
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Check also if RCU has been disabled.
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Reported-by: "John B. Wyatt IV" <jwyatt@redhat.com>
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Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/gpu/drm/i915/gt/uc/intel_guc.h | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
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+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
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@@ -362,7 +362,7 @@ static inline int intel_guc_send_busy_lo
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{
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int err;
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unsigned int sleep_period_ms = 1;
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- bool not_atomic = !in_atomic() && !irqs_disabled();
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+ bool not_atomic = !in_atomic() && !irqs_disabled() && !rcu_preempt_depth();
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/*
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* FIXME: Have caller pass in if we are in an atomic context to avoid
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