[PATCH RT v2] tracing: make preempt_lazy and migrate_disable counter smaller

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

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>
---
v1…v2:
  - drop the `padding' member
  - update the members in trace_define_common_fields() to match struct
    trace_entry.

 include/linux/trace_events.h | 3 +--
 kernel/trace/trace_events.c  | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index f3b1ef07e4a5f..10bbf986bc1d5 100644
--- 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;
 };
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index accaae59a7626..8bfb187cce65a 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -181,8 +181,8 @@ static int trace_define_common_fields(void)
 	__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;
 }
-- 
2.25.1