61 lines
2.2 KiB
Diff
61 lines
2.2 KiB
Diff
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 6 Dec 2018 09:52:20 +0100
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Subject: [PATCH 4/8] drm/i915: Disable tracing points on PREEMPT_RT
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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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Luca Abeni reported this:
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| BUG: scheduling while atomic: kworker/u8:2/15203/0x00000003
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| CPU: 1 PID: 15203 Comm: kworker/u8:2 Not tainted 4.19.1-rt3 #10
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| Call Trace:
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| rt_spin_lock+0x3f/0x50
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| gen6_read32+0x45/0x1d0 [i915]
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| g4x_get_vblank_counter+0x36/0x40 [i915]
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| trace_event_raw_event_i915_pipe_update_start+0x7d/0xf0 [i915]
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The tracing events use trace_intel_pipe_update_start() among other events
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use functions acquire spinlock_t locks which are transformed into
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sleeping locks on PREEMPT_RT. A few trace points use
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intel_get_crtc_scanline(), others use ->get_vblank_counter() wich also
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might acquire a sleeping locks on PREEMPT_RT.
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At the time the arguments are evaluated within trace point, preemption
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is disabled and so the locks must not be acquired on PREEMPT_RT.
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Based on this I don't see any other way than disable trace points on
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PREMPT_RT.
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Acked-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
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Reported-by: Luca Abeni <lucabe72@gmail.com>
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Cc: Steven Rostedt <rostedt@goodmis.org>
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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/display/intel_display_trace.h | 4 ++++
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drivers/gpu/drm/i915/i915_trace.h | 4 ++++
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2 files changed, 8 insertions(+)
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--- a/drivers/gpu/drm/i915/display/intel_display_trace.h
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+++ b/drivers/gpu/drm/i915/display/intel_display_trace.h
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@@ -9,6 +9,10 @@
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#if !defined(__INTEL_DISPLAY_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ)
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#define __INTEL_DISPLAY_TRACE_H__
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+#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE)
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+#define NOTRACE
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+#endif
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+
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#include <linux/string_helpers.h>
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#include <linux/types.h>
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#include <linux/tracepoint.h>
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--- a/drivers/gpu/drm/i915/i915_trace.h
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+++ b/drivers/gpu/drm/i915/i915_trace.h
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@@ -6,6 +6,10 @@
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#if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)
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#define _I915_TRACE_H_
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+#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE)
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+#define NOTRACE
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+#endif
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+
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#include <linux/stringify.h>
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#include <linux/types.h>
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#include <linux/tracepoint.h>
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