drm/i915: Disable tracing points on PREEMPT_RT

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

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
PREMPT_RT.

Reported-by: Luca Abeni <lucabe72@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
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

2018-12-06 09:52:20 +01:00

committed by

Kevin Becker

parent 1b9bd81c8a

commit af6ef9a965

1 changed files with 4 additions and 0 deletions

									
										drivers/gpu/drm/i915/i915_trace.h
									
		+4
		
												View File
												
				@@ -6,6 +6,10 @@

				#if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)

				#define _I915_TRACE_H_

				#ifdef CONFIG_PREEMPT_RT

				#define NOTRACE

				#endif

				#include <linux/stringify.h>

				#include <linux/types.h>

				#include <linux/tracepoint.h>