markers: auto enable tracepoints (new API : trace_mark_tp())

Impact: new API

Add a new API trace_mark_tp(), which declares a marker within a
tracepoint probe. When the marker is activated, the tracepoint is
automatically enabled.

No branch test is used at the marker site, because it would be a
duplicate of the branch already present in the tracepoint.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mathieu Desnoyers 2008-11-14 17:47:39 -05:00 committed by Ingo Molnar
parent a419246ac7
commit c1df1bd2c4
3 changed files with 96 additions and 3 deletions

View file

@ -49,6 +49,8 @@ struct marker {
void (*call)(const struct marker *mdata, void *call_private, ...);
struct marker_probe_closure single;
struct marker_probe_closure *multi;
const char *tp_name; /* Optional tracepoint name */
void *tp_cb; /* Optional tracepoint callback */
} __attribute__((aligned(8)));
#ifdef CONFIG_MARKERS
@ -73,7 +75,7 @@ struct marker {
__attribute__((section("__markers"), aligned(8))) = \
{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)], \
0, 0, marker_probe_cb, \
{ __mark_empty_function, NULL}, NULL }; \
{ __mark_empty_function, NULL}, NULL, NULL, NULL }; \
__mark_check_format(format, ## args); \
if (unlikely(__mark_##name.state)) { \
(*__mark_##name.call) \
@ -81,11 +83,38 @@ struct marker {
} \
} while (0)
#define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
do { \
void __check_tp_type(void) \
{ \
register_trace_##tp_name(tp_cb); \
} \
static const char __mstrtab_##name[] \
__attribute__((section("__markers_strings"))) \
= #name "\0" format; \
static struct marker __mark_##name \
__attribute__((section("__markers"), aligned(8))) = \
{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)], \
0, 0, marker_probe_cb, \
{ __mark_empty_function, NULL}, NULL, #tp_name, tp_cb };\
__mark_check_format(format, ## args); \
(*__mark_##name.call)(&__mark_##name, call_private, \
## args); \
} while (0)
extern void marker_update_probe_range(struct marker *begin,
struct marker *end);
#else /* !CONFIG_MARKERS */
#define __trace_mark(generic, name, call_private, format, args...) \
__mark_check_format(format, ## args)
#define __trace_mark_tp(name, call_private, tp_name, tp_cb, format, args...) \
do { \
void __check_tp_type(void) \
{ \
register_trace_##tp_name(tp_cb); \
} \
__mark_check_format(format, ## args); \
} while (0)
static inline void marker_update_probe_range(struct marker *begin,
struct marker *end)
{ }
@ -117,6 +146,20 @@ static inline void marker_update_probe_range(struct marker *begin,
#define _trace_mark(name, format, args...) \
__trace_mark(1, name, NULL, format, ## args)
/**
* trace_mark_tp - Marker in a tracepoint callback
* @name: marker name, not quoted.
* @tp_name: tracepoint name, not quoted.
* @tp_cb: tracepoint callback. Should have an associated global symbol so it
* is not optimized away by the compiler (should not be static).
* @format: format string
* @args...: variable argument list
*
* Places a marker in a tracepoint callback.
*/
#define trace_mark_tp(name, tp_name, tp_cb, format, args...) \
__trace_mark_tp(name, NULL, tp_name, tp_cb, format, ## args)
/**
* MARK_NOARGS - Format string for a marker with no argument.
*/

View file

@ -808,6 +808,7 @@ config TRACEPOINTS
config MARKERS
bool "Activate markers"
depends on TRACEPOINTS
help
Place an empty function call at each marker site. Can be
dynamically changed for a probe function.

View file

@ -479,7 +479,7 @@ static int marker_set_format(struct marker_entry *entry, const char *format)
static int set_marker(struct marker_entry *entry, struct marker *elem,
int active)
{
int ret;
int ret = 0;
WARN_ON(strcmp(entry->name, elem->name) != 0);
if (entry->format) {
@ -531,9 +531,40 @@ static int set_marker(struct marker_entry *entry, struct marker *elem,
*/
smp_wmb();
elem->ptype = entry->ptype;
if (elem->tp_name && (active ^ elem->state)) {
WARN_ON(!elem->tp_cb);
/*
* It is ok to directly call the probe registration because type
* checking has been done in the __trace_mark_tp() macro.
*/
if (active) {
/*
* try_module_get should always succeed because we hold
* lock_module() to get the tp_cb address.
*/
ret = try_module_get(__module_text_address(
(unsigned long)elem->tp_cb));
BUG_ON(!ret);
ret = tracepoint_probe_register_noupdate(
elem->tp_name,
elem->tp_cb);
} else {
ret = tracepoint_probe_unregister_noupdate(
elem->tp_name,
elem->tp_cb);
/*
* tracepoint_probe_update_all() must be called
* before the module containing tp_cb is unloaded.
*/
module_put(__module_text_address(
(unsigned long)elem->tp_cb));
}
}
elem->state = active;
return 0;
return ret;
}
/*
@ -544,7 +575,24 @@ static int set_marker(struct marker_entry *entry, struct marker *elem,
*/
static void disable_marker(struct marker *elem)
{
int ret;
/* leave "call" as is. It is known statically. */
if (elem->tp_name && elem->state) {
WARN_ON(!elem->tp_cb);
/*
* It is ok to directly call the probe registration because type
* checking has been done in the __trace_mark_tp() macro.
*/
ret = tracepoint_probe_unregister_noupdate(elem->tp_name,
elem->tp_cb);
WARN_ON(ret);
/*
* tracepoint_probe_update_all() must be called
* before the module containing tp_cb is unloaded.
*/
module_put(__module_text_address((unsigned long)elem->tp_cb));
}
elem->state = 0;
elem->single.func = __mark_empty_function;
/* Update the function before setting the ptype */
@ -608,6 +656,7 @@ static void marker_update_probes(void)
marker_update_probe_range(__start___markers, __stop___markers);
/* Markers in modules. */
module_update_markers();
tracepoint_probe_update_all();
}
/**