[patch 12/12] Tracepoints - Immediate Values

Mathieu Desnoyers
2009-09-24T14:43:21Z

[-- Attachment #1: tracepoints-immediate-values.patch --]
[-- Type: text/plain, Size: 5047 bytes --]

Use immediate values in tracepoints.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: 'Peter Zijlstra' <peterz@infradead.org>
CC: "Frank Ch. Eigler" <fche@redhat.com>
CC: 'Ingo Molnar' <mingo@elte.hu>
CC: 'Hideo AOKI' <haoki@redhat.com>
CC: Takashi Nishiie <t-nishiie@np.css.fujitsu.com>
CC: 'Steven Rostedt' <rostedt@goodmis.org>
---
include/linux/tracepoint.h | 33 +++++++++++++++++++++++++++------
kernel/tracepoint.c | 14 +++++++++-----
2 files changed, 36 insertions(+), 11 deletions(-)

Index: linux.trees.git/include/linux/tracepoint.h
===================================================================
--- linux.trees.git.orig/include/linux/tracepoint.h 2009-09-24 08:52:55.000000000 -0400
+++ linux.trees.git/include/linux/tracepoint.h 2009-09-24 09:05:29.000000000 -0400
@@ -14,6 +14,7 @@
* See the file COPYING for more details.
*/

+#include <linux/immediate.h>
#include <linux/types.h>
#include <linux/rcupdate.h>

@@ -22,7 +23,7 @@ struct tracepoint;

struct tracepoint {
const char *name; /* Tracepoint name */
- int state; /* State. */
+ DEFINE_IMV(char, state); /* State. */
void (*regfunc)(void);
void (*unregfunc)(void);
void **funcs;
@@ -58,18 +59,38 @@ struct tracepoint {
rcu_read_unlock_sched_notrace(); \
} while (0)

+#define __CHECK_TRACE(name, generic, proto, args) \
+ do { \
+ if (!generic) { \
+ if (unlikely(imv_read(__tracepoint_##name.state))) \
+ __DO_TRACE(&__tracepoint_##name, \
+ TP_PROTO(proto), TP_ARGS(args));\
+ } else { \
+ if (unlikely(_imv_read(__tracepoint_##name.state))) \
+ __DO_TRACE(&__tracepoint_##name, \
+ TP_PROTO(proto), TP_ARGS(args));\
+ } \
+ } while (0)
+
/*
* Make sure the alignment of the structure in the __tracepoints section will
* not add unwanted padding between the beginning of the section and the
* structure. Force alignment to the same alignment as the section start.
+ *
+ * The "generic" argument, passed to the declared __trace_##name inline
+ * function controls which tracepoint enabling mechanism must be used.
+ * If generic is true, a variable read is used.
+ * If generic is false, immediate values are used.
*/
#define DECLARE_TRACE(name, proto, args) \
extern struct tracepoint __tracepoint_##name; \
static inline void trace_##name(proto) \
{ \
- if (unlikely(__tracepoint_##name.state)) \
- __DO_TRACE(&__tracepoint_##name, \
- TP_PROTO(proto), TP_ARGS(args)); \
+ __CHECK_TRACE(name, 0, TP_PROTO(proto), TP_ARGS(args)); \
+ } \
+ static inline void _trace_##name(proto) \
+ { \
+ __CHECK_TRACE(name, 1, TP_PROTO(proto), TP_ARGS(args)); \
} \
static inline int register_trace_##name(void (*probe)(proto)) \
{ \
@@ -101,10 +122,10 @@ extern void tracepoint_update_probe_rang

#else /* !CONFIG_TRACEPOINTS */
#define DECLARE_TRACE(name, proto, args) \
- static inline void _do_trace_##name(struct tracepoint *tp, proto) \
- { } \
static inline void trace_##name(proto) \
{ } \
+ static inline void _trace_##name(proto) \
+ { } \
static inline int register_trace_##name(void (*probe)(proto)) \
{ \
return -ENOSYS; \
Index: linux.trees.git/kernel/tracepoint.c
===================================================================
--- linux.trees.git.orig/kernel/tracepoint.c 2009-09-24 08:52:55.000000000 -0400
+++ linux.trees.git/kernel/tracepoint.c 2009-09-24 09:11:13.000000000 -0400
@@ -25,6 +25,7 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/immediate.h>

extern struct tracepoint __start___tracepoints[];
extern struct tracepoint __stop___tracepoints[];
@@ -243,9 +244,9 @@ static void set_tracepoint(struct tracep
{
WARN_ON(strcmp((*entry)->name, elem->name) != 0);

- if (elem->regfunc && !elem->state && active)
+ if (elem->regfunc && !_imv_read(elem->state) && active)
elem->regfunc();
- else if (elem->unregfunc && elem->state && !active)
+ else if (elem->unregfunc && _imv_read(elem->state) && !active)
elem->unregfunc();

/*
@@ -256,7 +257,7 @@ static void set_tracepoint(struct tracep
* is used.
*/
rcu_assign_pointer(elem->funcs, (*entry)->funcs);
- elem->state = active;
+ elem->state__imv = active;
}

/*
@@ -267,10 +268,10 @@ static void set_tracepoint(struct tracep
*/
static void disable_tracepoint(struct tracepoint *elem)
{
- if (elem->unregfunc && elem->state)
+ if (elem->unregfunc && _imv_read(elem->state))
elem->unregfunc();

- elem->state = 0;
+ elem->state__imv = 0;
rcu_assign_pointer(elem->funcs, NULL);
}

@@ -313,6 +314,9 @@ static void tracepoint_update_probes(voi
__stop___tracepoints);
/* tracepoints in modules. */
module_update_tracepoints();
+ /* Update immediate values */
+ core_imv_update();
+ module_imv_update();
}

static void *tracepoint_add_probe(const char *name, void *probe)