From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 21 Feb 2020 18:15:15 +0100
Subject: [PATCH] tracing: make preempt_lazy and migrate_disable counter
 smaller
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: 0d4c8fdf89389ea449c6c16e8715b230897d9414
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

The migrate_disable counter should not exceed 255 so it is enough to
store it in an 8bit field.
With this change we can move the `preempt_lazy_count' member into the
gap so the whole struct shrinks by 4 bytes to 12 bytes in total.
Remove the `padding' field, it is not needed.
Update the tracing fields in trace_define_common_fields() (it was
missing the preempt_lazy_count field).

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
---
 include/linux/trace_events.h |    3 +--
 kernel/trace/trace_events.c  |    4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -62,8 +62,7 @@ struct trace_entry {
 	unsigned char		flags;
 	unsigned char		preempt_count;
 	int			pid;
-	unsigned short		migrate_disable;
-	unsigned short		padding;
+	unsigned char		migrate_disable;
 	unsigned char		preempt_lazy_count;
 };
 
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -181,8 +181,8 @@ static int trace_define_common_fields(vo
 	__common_field(unsigned char, flags);
 	__common_field(unsigned char, preempt_count);
 	__common_field(int, pid);
-	__common_field(unsigned short, migrate_disable);
-	__common_field(unsigned short, padding);
+	__common_field(unsigned char, migrate_disable);
+	__common_field(unsigned char, preempt_lazy_count);
 
 	return ret;
 }