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-rw-r--r--debian/patches-rt/drm-i915-guc-Consider-also-RCU-depth-in-busy-loop.patch29
1 files changed, 29 insertions, 0 deletions
diff --git a/debian/patches-rt/drm-i915-guc-Consider-also-RCU-depth-in-busy-loop.patch b/debian/patches-rt/drm-i915-guc-Consider-also-RCU-depth-in-busy-loop.patch
new file mode 100644
index 0000000000..0f030b42f2
--- /dev/null
+++ b/debian/patches-rt/drm-i915-guc-Consider-also-RCU-depth-in-busy-loop.patch
@@ -0,0 +1,29 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Tue, 3 Oct 2023 21:37:21 +0200
+Subject: [PATCH] drm/i915/guc: Consider also RCU depth in busy loop.
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
+
+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>
+---
+ drivers/gpu/drm/i915/gt/uc/intel_guc.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h
++++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h
+@@ -317,7 +317,7 @@ static inline int intel_guc_send_busy_lo
+ {
+ 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