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tracing/events: introduce __dynamic_array()

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__string() is limited:

  - it's a char array, but we may want to define array with other types
  - a source string should be available, but we may just know the string size

We introduce __dynamic_array() to break those limitations, and __string()
becomes a wrapper of it. As a side effect, now __get_str() can be used
in TP_fast_assign but not only TP_print.

Take XFS for example, we have the string length in the dirent, but the
string itself is not NULL-terminated, so __dynamic_array() can be used:

TRACE_EVENT(xfs_dir2,
	TP_PROTO(struct xfs_da_args *args),
	TP_ARGS(args),

	TP_STRUCT__entry(
		__field(int, namelen)
		__dynamic_array(char, name, args->namelen + 1)
		...
	),

	TP_fast_assign(
		char *name = __get_str(name);

		if (args->namelen)
			memcpy(name, args->name, args->namelen);
		name[args->namelen] = '\0';

		__entry->namelen = args->namelen;
	),

	TP_printk("name %.*s namelen %d",
		  __entry->namelen ? __get_str(name) : NULL
		  __entry->namelen)
);

[ Impact: allow defining dynamic size arrays ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A2384D2.3080403@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Li Zefan 2009-06-01 15:35:46 +08:00 committed by Steven Rostedt
parent a9c1c3abe1
commit 7fcb7c472f
2 changed files with 93 additions and 39 deletions
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126
include/trace/ftrace.h
View File

@ -18,14 +18,17 @@
#include <linux/ftrace_event.h>
#undef __array
#define __array(type, item, len) type item[len];
#undef __field
#define __field(type, item) type item;
#undef __array
#define __array(type, item, len) type item[len];
#undef __dynamic_array
#define __dynamic_array(type, item, len) unsigned short __data_loc_##item;
#undef __string
#define __string(item, src) unsigned short __str_loc_##item;
#define __string(item, src) __dynamic_array(char, item, -1)
#undef TP_STRUCT__entry
#define TP_STRUCT__entry(args...) args
@ -35,7 +38,7 @@
struct ftrace_raw_##name { \
struct trace_entry ent; \
tstruct \
char __str_data[0]; \
char __data[0]; \
}; \
static struct ftrace_event_call event_##name
@ -47,30 +50,31 @@
*
* Include the following:
*
* struct ftrace_str_offsets_<call> {
* int <str1>;
* int <str2>;
* struct ftrace_data_offsets_<call> {
* int <item1>;
* int <item2>;
* [...]
* };
*
* The __string() macro will create each int <str>, this is to
* keep the offset of each string from the beggining of the event
* once we perform the strlen() of the src strings.
*
* The __dynamic_array() macro will create each int <item>, this is
* to keep the offset of each array from the beginning of the event.
*/
#undef __array
#define __array(type, item, len)
#undef __field
#define __field(type, item);
#undef __array
#define __array(type, item, len)
#undef __dynamic_array
#define __dynamic_array(type, item, len) int item;
#undef __string
#define __string(item, src) int item;
#define __string(item, src) __dynamic_array(char, item, -1)
#undef TRACE_EVENT
#define TRACE_EVENT(call, proto, args, tstruct, assign, print) \
struct ftrace_str_offsets_##call { \
struct ftrace_data_offsets_##call { \
tstruct; \
};
@ -119,8 +123,12 @@
#undef TP_printk
#define TP_printk(fmt, args...) fmt "\n", args
#undef __get_dynamic_array
#define __get_dynamic_array(field) \
((void *)__entry + __entry->__data_loc_##field)
#undef __get_str
#define __get_str(field) ((char *)__entry + __entry->__str_loc_##field)
#define __get_str(field) (char *)__get_dynamic_array(field)
#undef __print_flags
#define __print_flags(flag, delim, flag_array...) \
@ -207,16 +215,19 @@ ftrace_raw_output_##call(struct trace_iterator *iter, int flags) \
if (!ret) \
return 0;
#undef __string
#define __string(item, src) \
ret = trace_seq_printf(s, "\tfield:__str_loc " #item ";\t" \
#undef __dynamic_array
#define __dynamic_array(type, item, len) \
ret = trace_seq_printf(s, "\tfield:__data_loc " #item ";\t" \
"offset:%u;\tsize:%u;\n", \
(unsigned int)offsetof(typeof(field), \
__str_loc_##item), \
(unsigned int)sizeof(field.__str_loc_##item)); \
__data_loc_##item), \
(unsigned int)sizeof(field.__data_loc_##item)); \
if (!ret) \
return 0;
#undef __string
#define __string(item, src) __dynamic_array(char, item, -1)
#undef __entry
#define __entry REC
@ -260,11 +271,14 @@ ftrace_format_##call(struct trace_seq *s) \
if (ret) \
return ret;
#undef __dynamic_array
#define __dynamic_array(type, item, len) \
ret = trace_define_field(event_call, "__data_loc" "[" #type "]", #item,\
offsetof(typeof(field), __data_loc_##item), \
sizeof(field.__data_loc_##item), 0);
#undef __string
#define __string(item, src) \
ret = trace_define_field(event_call, "__str_loc", #item, \
offsetof(typeof(field), __str_loc_##item), \
sizeof(field.__str_loc_##item), 0);
#define __string(item, src) __dynamic_array(char, item, -1)
#undef TRACE_EVENT
#define TRACE_EVENT(call, proto, args, tstruct, func, print) \
@ -288,6 +302,43 @@ ftrace_define_fields_##call(void) \
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
/*
* remember the offset of each array from the beginning of the event.
*/
#undef __entry
#define __entry entry
#undef __field
#define __field(type, item)
#undef __array
#define __array(type, item, len)
#undef __dynamic_array
#define __dynamic_array(type, item, len) \
__data_offsets->item = __data_size + \
offsetof(typeof(*entry), __data); \
__data_size += (len) * sizeof(type);
#undef __string
#define __string(item, src) __dynamic_array(char, item, strlen(src) + 1) \
#undef TRACE_EVENT
#define TRACE_EVENT(call, proto, args, tstruct, assign, print) \
static inline int ftrace_get_offsets_##call( \
struct ftrace_data_offsets_##call *__data_offsets, proto) \
{ \
int __data_size = 0; \
struct ftrace_raw_##call __maybe_unused *entry; \
\
tstruct; \
\
return __data_size; \
}
#include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
/*
* Stage 4 of the trace events.
*
@ -432,15 +483,15 @@ static void ftrace_profile_disable_##call(struct ftrace_event_call *event_call)\
#undef __array
#define __array(type, item, len)
#undef __dynamic_array
#define __dynamic_array(type, item, len) \
__entry->__data_loc_##item = __data_offsets.item;
#undef __string
#define __string(item, src) \
__str_offsets.item = __str_size + \
offsetof(typeof(*entry), __str_data); \
__str_size += strlen(src) + 1;
#define __string(item, src) __dynamic_array(char, item, -1) \
#undef __assign_str
#define __assign_str(dst, src) \
__entry->__str_loc_##dst = __str_offsets.dst; \
strcpy(__get_str(dst), src);
#undef TRACE_EVENT
@ -451,26 +502,29 @@ static struct ftrace_event_call event_##call; \
\
static void ftrace_raw_event_##call(proto) \
{ \
struct ftrace_str_offsets_##call __maybe_unused __str_offsets; \
struct ftrace_data_offsets_##call __maybe_unused __data_offsets;\
struct ftrace_event_call *event_call = &event_##call; \
struct ring_buffer_event *event; \
struct ftrace_raw_##call *entry; \
unsigned long irq_flags; \
int __str_size = 0; \
int __data_size; \
int pc; \
\
local_save_flags(irq_flags); \
pc = preempt_count(); \
\
tstruct; \
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
\
event = trace_current_buffer_lock_reserve(event_##call.id, \
sizeof(struct ftrace_raw_##call) + __str_size,\
sizeof(*entry) + __data_size, \
irq_flags, pc); \
if (!event) \
return; \
entry = ring_buffer_event_data(event); \
\
\
tstruct \
\
{ assign; } \
\
if (!filter_current_check_discard(event_call, entry, event)) \

6
kernel/trace/trace_events_filter.c
View File

@ -478,12 +478,12 @@ enum {
static int is_string_field(const char *type)
{
if (strstr(type, "__data_loc") && strstr(type, "char"))
return FILTER_DYN_STRING;
if (strchr(type, '[') && strstr(type, "char"))
return FILTER_STATIC_STRING;
if (!strcmp(type, "__str_loc"))
return FILTER_DYN_STRING;
return 0;
}