[PATCH 1/2] tracing/syscalls: Annotate raw_init function with __init

[PATCH 1/2] tracing/syscalls: Annotate raw_init function with __init

[Li Zefan]

init_syscall_trace() can be called during kernel bootup only, so we can
mark it and the functions it calls as __init.

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 kernel/trace/trace_syscalls.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 8f2ac73..1de2ba6 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -200,8 +200,8 @@ extern char *__bad_type_size(void);
 		#type, #name, offsetof(typeof(trace), name),		\
 		sizeof(trace.name), is_signed_type(type)
 
-static
-int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
+static int __init
+__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 {
 	int i;
 	int pos = 0;
@@ -228,7 +228,7 @@ int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 	return pos;
 }
 
-static int set_syscall_print_fmt(struct ftrace_event_call *call)
+static int __init set_syscall_print_fmt(struct ftrace_event_call *call)
 {
 	char *print_fmt;
 	int len;
@@ -253,7 +253,7 @@ static int set_syscall_print_fmt(struct ftrace_event_call *call)
 	return 0;
 }
 
-static void free_syscall_print_fmt(struct ftrace_event_call *call)
+static void __init free_syscall_print_fmt(struct ftrace_event_call *call)
 {
 	struct syscall_metadata *entry = call->data;
 
@@ -446,7 +446,7 @@ static void unreg_event_syscall_exit(struct ftrace_event_file *file,
 	mutex_unlock(&syscall_trace_lock);
 }
 
-static int init_syscall_trace(struct ftrace_event_call *call)
+static int __init init_syscall_trace(struct ftrace_event_call *call)
 {
 	int id;
 	int num;
-- 
1.8.0.2

[PATCH 2/2] tracing: Shrink the size of struct ftrace_event_field

[Li Zefan]

Use bit fields, and the size of struct ftrace_event_field can be
shrunk from 48 bytes to 40 bytes on 64bit kernel.

slab_name active_obj nr_obj size obj_per_slab
---------------------------------------------
ftrace_event_field   1105   1105     48   85  (before)
ftrace_event_field   1224   1224     40  102  (after)

This saves a few Kbytes: (1224 * 40) - (1105 * 48) = 4080

Signed-off-by: Li Zefan <lizefan@huawei.com>
---
 kernel/trace/trace.h        | 8 ++++----
 kernel/trace/trace_events.c | 5 +++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9e01458..a3365a4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -916,10 +916,10 @@ struct ftrace_event_field {
 	struct list_head	link;
 	const char		*name;
 	const char		*type;
-	int			filter_type;
-	int			offset;
-	int			size;
-	int			is_signed;
+	unsigned int		filter_type:4;
+	unsigned int		offset:12;
+	unsigned int		size:12;
+	unsigned int		is_signed:1;
 };
 
 struct event_filter {
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 53582e9..67aee85 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -111,6 +111,11 @@ static int __trace_define_field(struct list_head *head, const char *type,
 	field->size = size;
 	field->is_signed = is_signed;
 
+	WARN_ON(offset >= (1 << 12));
+	WARN_ON(size >= (1 << 12));
+	WARN_ON(is_signed >= (1 << 1));
+	WARN_ON(field->filter_type >= (1 << 4));
+
 	list_add(&field->link, head);
 
 	return 0;
-- 
1.8.0.2