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-rw-r--r--debian/patches-rt/drm-i915-Disable-tracing-points-on-PREEMPT_RT.patch59
1 files changed, 59 insertions, 0 deletions
diff --git a/debian/patches-rt/drm-i915-Disable-tracing-points-on-PREEMPT_RT.patch b/debian/patches-rt/drm-i915-Disable-tracing-points-on-PREEMPT_RT.patch
new file mode 100644
index 0000000000..33a7f3cc72
--- /dev/null
+++ b/debian/patches-rt/drm-i915-Disable-tracing-points-on-PREEMPT_RT.patch
@@ -0,0 +1,59 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Thu, 6 Dec 2018 09:52:20 +0100
+Subject: [PATCH] drm/i915: Disable tracing points on PREEMPT_RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz
+
+Luca Abeni reported this:
+| BUG: scheduling while atomic: kworker/u8:2/15203/0x00000003
+| CPU: 1 PID: 15203 Comm: kworker/u8:2 Not tainted 4.19.1-rt3 #10
+| Call Trace:
+| rt_spin_lock+0x3f/0x50
+| gen6_read32+0x45/0x1d0 [i915]
+| g4x_get_vblank_counter+0x36/0x40 [i915]
+| trace_event_raw_event_i915_pipe_update_start+0x7d/0xf0 [i915]
+
+The tracing events use trace_intel_pipe_update_start() among other events
+use functions acquire spinlock_t locks which are transformed into
+sleeping locks on PREEMPT_RT. A few trace points use
+intel_get_crtc_scanline(), others use ->get_vblank_counter() wich also
+might acquire a sleeping locks on PREEMPT_RT.
+At the time the arguments are evaluated within trace point, preemption
+is disabled and so the locks must not be acquired on PREEMPT_RT.
+
+Based on this I don't see any other way than disable trace points on
+PREMPT_RT.
+
+Reported-by: Luca Abeni <lucabe72@gmail.com>
+Cc: Steven Rostedt <rostedt@goodmis.org>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ drivers/gpu/drm/i915/display/intel_display_trace.h | 4 ++++
+ drivers/gpu/drm/i915/i915_trace.h | 4 ++++
+ 2 files changed, 8 insertions(+)
+
+--- a/drivers/gpu/drm/i915/display/intel_display_trace.h
++++ b/drivers/gpu/drm/i915/display/intel_display_trace.h
+@@ -9,6 +9,10 @@
+ #if !defined(__INTEL_DISPLAY_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ)
+ #define __INTEL_DISPLAY_TRACE_H__
+
++#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE)
++#define NOTRACE
++#endif
++
+ #include <linux/string_helpers.h>
+ #include <linux/types.h>
+ #include <linux/tracepoint.h>
+--- a/drivers/gpu/drm/i915/i915_trace.h
++++ b/drivers/gpu/drm/i915/i915_trace.h
+@@ -6,6 +6,10 @@
+ #if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)
+ #define _I915_TRACE_H_
+
++#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE)
++#define NOTRACE
++#endif
++
+ #include <linux/stringify.h>
+ #include <linux/types.h>
+ #include <linux/tracepoint.h>