From d781d9ceee9e4e8bf7e7ad247341cee4b0d69335 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <>
Date: Thu, 6 Dec 2018 09:52:20 +0100
Subject: [PATCH 114/166] drm/i915: Disable tracing points on PREEMPT_RT

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_i915_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

Reported-by: Luca Abeni <>
Cc: Steven Rostedt <>
Signed-off-by: Sebastian Andrzej Siewior <>
 drivers/gpu/drm/i915/i915_trace.h |    4 ++++
 1 file changed, 4 insertions(+)

Index: linux-5.15.32-rt39/drivers/gpu/drm/i915/i915_trace.h
@ linux-5.15.32-rt39/drivers/gpu/drm/i915/i915_trace.h:5 @
 #if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)
 #define _I915_TRACE_H_
+#define NOTRACE
 #include <linux/stringify.h>
 #include <linux/types.h>
 #include <linux/tracepoint.h>