Re: [PATCH][RFC] tracing: Use class->reg() for all registering of events

Peter Zijlstra
2010-06-08T15:57:59Z

On Tue, 2010-06-08 at 11:33 -0400, Steven Rostedt wrote:
> 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?

I'll have a look soon, but lets add Srikar to CC, he actually reported
the problem :-)

> 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@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@infradead.org>
> Signed-off-by: Steven Rostedt <rostedt@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
>
>