linux-kernel - [PATCH v2 1/3] tracing: Replace TRACE_FLAG_IRQS

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Message-ID: <20241021151257.102296-2-bigeasy@linutronix.de>
Date: Mon, 21 Oct 2024 17:08:40 +0200
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: linux-trace-kernel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
	tglx@...utronix.de,
	mingo@...nel.org,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com,
	mgorman@...e.de,
	vschneid@...hat.com,
	ankur.a.arora@...cle.com,
	efault@....de,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v2 1/3] tracing: Replace TRACE_FLAG_IRQS_NOSUPPORT with its config option.

From: Thomas Gleixner <tglx@...utronix.de>

The TRACE_FLAG_IRQS_NOSUPPORT flag is used by tracing_gen_ctx.*() to
signal that CONFIG_TRACE_IRQFLAGS_SUPPORT is not enabled and tracing IRQ
flags is not supported.

This could be replaced by using the 0 as flags and then deducting that
there is no IRQFLAGS_SUPPORT based on the config option. The downside is
that without CONFIG_TRACE_IRQFLAGS_SUPPORT we can not distinguish
between no-IRQ passed flags and callers which passed 0. On the upside we
have room for one additional flags which could be used for LAZY_PREEMPTION.

Remove TRACE_FLAG_IRQS_NOSUPPORT and set it flags are 0 and
CONFIG_TRACE_IRQFLAGS_SUPPORT is not set.

[bigeasy: Commit descrption.]

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/linux/trace_events.h |    7 +++----
 kernel/trace/trace_output.c  |    2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -184,8 +184,7 @@ unsigned int tracing_gen_ctx_irq_test(un
 
 enum trace_flag_type {
 	TRACE_FLAG_IRQS_OFF		= 0x01,
-	TRACE_FLAG_IRQS_NOSUPPORT	= 0x02,
-	TRACE_FLAG_NEED_RESCHED		= 0x04,
+	TRACE_FLAG_NEED_RESCHED		= 0x02,
 	TRACE_FLAG_HARDIRQ		= 0x08,
 	TRACE_FLAG_SOFTIRQ		= 0x10,
 	TRACE_FLAG_PREEMPT_RESCHED	= 0x20,
@@ -211,11 +210,11 @@ static inline unsigned int tracing_gen_c
 
 static inline unsigned int tracing_gen_ctx_flags(unsigned long irqflags)
 {
-	return tracing_gen_ctx_irq_test(TRACE_FLAG_IRQS_NOSUPPORT);
+	return tracing_gen_ctx_irq_test(0);
 }
 static inline unsigned int tracing_gen_ctx(void)
 {
-	return tracing_gen_ctx_irq_test(TRACE_FLAG_IRQS_NOSUPPORT);
+	return tracing_gen_ctx_irq_test(0);
 }
 #endif
 
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -460,7 +460,7 @@ int trace_print_lat_fmt(struct trace_seq
 		(entry->flags & TRACE_FLAG_IRQS_OFF && bh_off) ? 'D' :
 		(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
 		bh_off ? 'b' :
-		(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' :
+		!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_SUPPORT) ? 'X' :
 		'.';
 
 	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |