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From: Steven Rostedt on 8 Jun 2010 11:40

I'm pushing this as an RFC first. This probably should be something that
makes it into 2.6.35.

Acks and perhaps a little testing from the perf and kprobe angle?

-- Steve


Steven Rostedt (1):
tracing: Use class->reg() for all registering of events

----
include/linux/ftrace_event.h | 3 ++
include/trace/ftrace.h | 2 +
kernel/trace/trace_event_perf.c | 17 ++----------
kernel/trace/trace_events.c | 55 +++++++++++++++++++++++++-------------
4 files changed, 44 insertions(+), 33 deletions(-)
---------------------------
commit 0ab320dbe5894d7b4eec7d7da3a270abc68e4992
Author: Steven Rostedt <srostedt(a)redhat.com>
Date: Tue Jun 8 11:22:06 2010 -0400

tracing: Use class->reg() for all registering of events

Because kprobes and syscalls need special processing to register
events, the class->reg() method was created to handle the differences.

But instead of creating a default ->reg for perf and ftrace events,
the code was scattered with:

if (class->reg)
class->reg();
else
default_reg();

This is messy and can also lead to bugs.

This patch cleans up this code and creates a default reg() entry for
the events allowing for the code to directly call the class->reg()
without the condition.

Reported-by: Peter Zijlstra <peterz(a)infradead.org>
Signed-off-by: Steven Rostedt <rostedt(a)goodmis.org>

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 3167f2d..a69bd32 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -146,6 +146,9 @@ struct ftrace_event_class {
int (*raw_init)(struct ftrace_event_call *);
};

+extern int ftrace_event_reg(struct ftrace_event_call *event,
+ enum trace_reg type);
+
enum {
TRACE_EVENT_FL_ENABLED_BIT,
TRACE_EVENT_FL_FILTERED_BIT,
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 5a64905..8815e27 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -439,6 +439,7 @@ static inline notrace int ftrace_get_offsets_##call( \
* .fields = LIST_HEAD_INIT(event_class_##call.fields),
* .raw_init = trace_event_raw_init,
* .probe = ftrace_raw_event_##call,
+ * .reg = ftrace_event_reg,
* };
*
* static struct ftrace_event_call __used
@@ -567,6 +568,7 @@ static struct ftrace_event_class __used event_class_##call = { \
.fields = LIST_HEAD_INIT(event_class_##call.fields),\
.raw_init = trace_event_raw_init, \
.probe = ftrace_raw_event_##call, \
+ .reg = ftrace_event_reg, \
_TRACE_PERF_INIT(call) \
};

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index e6f6588..de2f170 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -56,13 +56,7 @@ static int perf_trace_event_init(struct ftrace_event_call *tp_event,
}
}

- if (tp_event->class->reg)
- ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
- else
- ret = tracepoint_probe_register(tp_event->name,
- tp_event->class->perf_probe,
- tp_event);
-
+ ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
if (ret)
goto fail;

@@ -96,7 +90,7 @@ int perf_trace_init(struct perf_event *p_event)
mutex_lock(&event_mutex);
list_for_each_entry(tp_event, &ftrace_events, list) {
if (tp_event->event.type == event_id &&
- tp_event->class && tp_event->class->perf_probe &&
+ tp_event->class && tp_event->class->reg &&
try_module_get(tp_event->mod)) {
ret = perf_trace_event_init(tp_event, p_event);
break;
@@ -136,12 +130,7 @@ void perf_trace_destroy(struct perf_event *p_event)
if (--tp_event->perf_refcount > 0)
goto out;

- if (tp_event->class->reg)
- tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
- else
- tracepoint_probe_unregister(tp_event->name,
- tp_event->class->perf_probe,
- tp_event);
+ tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);

/*
* Ensure our callback won't be called anymore. See
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 45a8968..b353639 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -132,6 +132,35 @@ int trace_event_raw_init(struct ftrace_event_call *call)
}
EXPORT_SYMBOL_GPL(trace_event_raw_init);

+int ftrace_event_reg(struct ftrace_event_call *call, enum trace_reg type)
+{
+ switch (type) {
+ case TRACE_REG_REGISTER:
+ return tracepoint_probe_register(call->name,
+ call->class->probe,
+ call);
+ case TRACE_REG_UNREGISTER:
+ tracepoint_probe_unregister(call->name,
+ call->class->probe,
+ call);
+ return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+ case TRACE_REG_PERF_REGISTER:
+ return tracepoint_probe_register(call->name,
+ call->class->perf_probe,
+ call);
+ case TRACE_REG_PERF_UNREGISTER:
+ tracepoint_probe_unregister(call->name,
+ call->class->perf_probe,
+ call);
+ return 0;
+#endif
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(ftrace_event_reg);
+
static int ftrace_event_enable_disable(struct ftrace_event_call *call,
int enable)
{
@@ -142,23 +171,13 @@ static int ftrace_event_enable_disable(struct ftrace_event_call *call,
if (call->flags & TRACE_EVENT_FL_ENABLED) {
call->flags &= ~TRACE_EVENT_FL_ENABLED;
tracing_stop_cmdline_record();
- if (call->class->reg)
- call->class->reg(call, TRACE_REG_UNREGISTER);
- else
- tracepoint_probe_unregister(call->name,
- call->class->probe,
- call);
+ call->class->reg(call, TRACE_REG_UNREGISTER);
}
break;
case 1:
if (!(call->flags & TRACE_EVENT_FL_ENABLED)) {
tracing_start_cmdline_record();
- if (call->class->reg)
- ret = call->class->reg(call, TRACE_REG_REGISTER);
- else
- ret = tracepoint_probe_register(call->name,
- call->class->probe,
- call);
+ ret = call->class->reg(call, TRACE_REG_REGISTER);
if (ret) {
tracing_stop_cmdline_record();
pr_info("event trace: Could not enable event "
@@ -196,8 +215,7 @@ static int __ftrace_set_clr_event(const char *match, const char *sub,
mutex_lock(&event_mutex);
list_for_each_entry(call, &ftrace_events, list) {

- if (!call->name || !call->class ||
- (!call->class->probe && !call->class->reg))
+ if (!call->name || !call->class || !call->class->reg)
continue;

if (match &&
@@ -323,7 +341,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
* The ftrace subsystem is for showing formats only.
* They can not be enabled or disabled via the event files.
*/
- if (call->class && (call->class->probe || call->class->reg))
+ if (call->class && call->class->reg)
return call;
}

@@ -476,8 +494,7 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,

mutex_lock(&event_mutex);
list_for_each_entry(call, &ftrace_events, list) {
- if (!call->name || !call->class ||
- (!call->class->probe && !call->class->reg))
+ if (!call->name || !call->class || !call->class->reg)
continue;

if (system && strcmp(call->class->system, system) != 0)
@@ -1037,12 +1054,12 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
return -1;
}

- if (call->class->probe || call->class->reg)
+ if (call->class->reg)
trace_create_file("enable", 0644, call->dir, call,
enable);

#ifdef CONFIG_PERF_EVENTS
- if (call->event.type && (call->class->perf_probe || call->class->reg))
+ if (call->event.type && call->class->reg)
trace_create_file("id", 0444, call->dir, call,
id);
#endif


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Prev: [PATCH] Staging: dt3155: remove DT_3155_* errno defines
Next: [RFC/T/D][PATCH 0/2] KVM page cache optimization (v2)