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The wakeup in preemptive (wip) monitor verifies if the
wakeup events always take place with preemption disabled:
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v
#==================#
H preemptive H <+
#==================# |
| |
| preempt_disable | preempt_enable
v |
sched_waking +------------------+ |
+--------------- | | |
| | non_preemptive | |
+--------------> | | -+
+------------------+
The wakeup event always takes place with preemption disabled because
of the scheduler synchronization. However, because the preempt_count
and its trace event are not atomic with regard to interrupts, some
inconsistencies might happen.
The documentation illustrates one of these cases.
Link: https://lkml.kernel.org/r/c98ca678df81115fddc04921b3c79720c836b18f.1659052063.git.bristot@kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
17 lines
602 B
Plaintext
17 lines
602 B
Plaintext
digraph state_automaton {
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{node [shape = circle] "non_preemptive"};
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{node [shape = plaintext, style=invis, label=""] "__init_preemptive"};
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{node [shape = doublecircle] "preemptive"};
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{node [shape = circle] "preemptive"};
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"__init_preemptive" -> "preemptive";
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"non_preemptive" [label = "non_preemptive"];
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"non_preemptive" -> "non_preemptive" [ label = "sched_waking" ];
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"non_preemptive" -> "preemptive" [ label = "preempt_enable" ];
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"preemptive" [label = "preemptive"];
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"preemptive" -> "non_preemptive" [ label = "preempt_disable" ];
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{ rank = min ;
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"__init_preemptive";
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"preemptive";
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}
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}
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