linux-kernel - [PATCH] tracing: uninline trace_trigger_soft

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Date:   Thu, 10 Feb 2022 09:47:52 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH] tracing: uninline trace_trigger_soft_disabled()

On a ppc32 build with CONFIG_CC_OPTIMISE_FOR_SIZE,
trace_trigger_soft_disabled() appears more than 50 times in vmlinux.

That function is rather big for an inlined function, and
it doesn't benefit much from inlining as its only parameter
is a pointer to a struct in memory:

	c003df60 <trace_trigger_soft_disabled>:
	c003df60:	94 21 ff f0 	stwu    r1,-16(r1)
	c003df64:	7c 08 02 a6 	mflr    r0
	c003df68:	90 01 00 14 	stw     r0,20(r1)
	c003df6c:	bf c1 00 08 	stmw    r30,8(r1)
	c003df70:	83 e3 00 24 	lwz     r31,36(r3)
	c003df74:	73 e9 01 00 	andi.   r9,r31,256
	c003df78:	41 82 00 10 	beq     c003df88 <trace_trigger_soft_disabled+0x28>
	c003df7c:	38 60 00 00 	li      r3,0
	c003df80:	39 61 00 10 	addi    r11,r1,16
	c003df84:	4b fd 60 ac 	b       c0014030 <_rest32gpr_30_x>
	c003df88:	73 e9 00 80 	andi.   r9,r31,128
	c003df8c:	7c 7e 1b 78 	mr      r30,r3
	c003df90:	41 a2 00 14 	beq     c003dfa4 <trace_trigger_soft_disabled+0x44>
	c003df94:	38 c0 00 00 	li      r6,0
	c003df98:	38 a0 00 00 	li      r5,0
	c003df9c:	38 80 00 00 	li      r4,0
	c003dfa0:	48 05 c5 f1 	bl      c009a590 <event_triggers_call>
	c003dfa4:	73 e9 00 40 	andi.   r9,r31,64
	c003dfa8:	40 82 00 28 	bne     c003dfd0 <trace_trigger_soft_disabled+0x70>
	c003dfac:	73 ff 02 00 	andi.   r31,r31,512
	c003dfb0:	41 82 ff cc 	beq     c003df7c <trace_trigger_soft_disabled+0x1c>
	c003dfb4:	80 01 00 14 	lwz     r0,20(r1)
	c003dfb8:	83 e1 00 0c 	lwz     r31,12(r1)
	c003dfbc:	7f c3 f3 78 	mr      r3,r30
	c003dfc0:	83 c1 00 08 	lwz     r30,8(r1)
	c003dfc4:	7c 08 03 a6 	mtlr    r0
	c003dfc8:	38 21 00 10 	addi    r1,r1,16
	c003dfcc:	48 05 6f 6c 	b       c0094f38 <trace_event_ignore_this_pid>
	c003dfd0:	38 60 00 01 	li      r3,1
	c003dfd4:	4b ff ff ac 	b       c003df80 <trace_trigger_soft_disabled+0x20>

It doesn't benefit much from inlining as its only parameter is a
pointer to a struct in memory so no constant folding is involved.

Uninline it and move it into kernel/trace/trace_events_trigger.c

It reduces the size of vmlinux by approximately 10 kbytes.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 include/linux/trace_events.h        | 16 +---------------
 kernel/trace/trace_events_trigger.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 70c069aef02c..23dc8a12008b 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -708,21 +708,7 @@ bool trace_event_ignore_this_pid(struct trace_event_file *trace_file);
  * triggers that require testing the fields, it will return true,
  * otherwise false.
  */
-static inline bool
-trace_trigger_soft_disabled(struct trace_event_file *file)
-{
-	unsigned long eflags = file->flags;
-
-	if (!(eflags & EVENT_FILE_FL_TRIGGER_COND)) {
-		if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
-			event_triggers_call(file, NULL, NULL, NULL);
-		if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
-			return true;
-		if (eflags & EVENT_FILE_FL_PID_FILTER)
-			return trace_event_ignore_this_pid(file);
-	}
-	return false;
-}
+bool trace_trigger_soft_disabled(struct trace_event_file *file);
 
 #ifdef CONFIG_BPF_EVENTS
 unsigned int trace_call_bpf(struct trace_event_call *call, void *ctx);
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index d00fee705f9c..41b766bc56b9 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -84,6 +84,22 @@ event_triggers_call(struct trace_event_file *file,
 }
 EXPORT_SYMBOL_GPL(event_triggers_call);
 
+bool trace_trigger_soft_disabled(struct trace_event_file *file)
+{
+	unsigned long eflags = file->flags;
+
+	if (!(eflags & EVENT_FILE_FL_TRIGGER_COND)) {
+		if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
+			event_triggers_call(file, NULL, NULL, NULL);
+		if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
+			return true;
+		if (eflags & EVENT_FILE_FL_PID_FILTER)
+			return trace_event_ignore_this_pid(file);
+	}
+	return false;
+}
+EXPORT_SYMBOL_GPL(trace_trigger_soft_disabled);
+
 /**
  * event_triggers_post_call - Call 'post_triggers' for a trace event
  * @file: The trace_event_file associated with the event
-- 
2.34.1