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SubjectRe: [PATCH -tip 02/13] [CLEANUP]tracing/kprobes: merge trace probe enable/disable functions
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On Mon, 2011-06-27 at 16:26 +0900, Masami Hiramatsu wrote:
> Merge redundant enable/disable functions into enable_trace_probe()
> and disable_trace_probe().
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> ---
>
> kernel/trace/trace_kprobe.c | 88 +++++++++++++++++--------------------------
> 1 files changed, 34 insertions(+), 54 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index bad87e9..ce5e6aa 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -683,6 +683,34 @@ static struct trace_probe *find_trace_probe(const char *event,
> return NULL;
> }
>
> +/* Enable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
> +static int enable_trace_probe(struct trace_probe *tp, int flag)
> +{
> + int ret = 0;
> +
> + tp->flags |= flag;
> + if (tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE)) {
> + if (trace_probe_is_return(tp))
> + ret = enable_kretprobe(&tp->rp);
> + else
> + ret = enable_kprobe(&tp->rp.kp);
> + }

Hmm, this seems weird. Should we have any protection here? I mean, is it
ok to call the enable_kprobe() twice? Or should we have something like:

{
int old_flags = tp->flags;
int ret = 0;
tp->flags |= flag;
if (!(old_flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE)) &&
flag & (TP_FLAG_TRACE | TP_FLAG_PROFILE)) {
[...]
}
return ret;
}

> +
> + return ret;
> +}
> +
> +/* Disable trace_probe - @flag must be TP_FLAG_TRACE or TP_FLAG_PROFILE */
> +static void disable_trace_probe(struct trace_probe *tp, int flag)
> +{
> + tp->flags &= ~flag;
> + if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
> + if (trace_probe_is_return(tp))
> + disable_kretprobe(&tp->rp);
> + else
> + disable_kprobe(&tp->rp.kp);
> + }
> +}

Same here.

Or do we want to reenable or re disable the probe?

-- Steve

> +
> /* Unregister a trace_probe and probe_event: call with locking probe_lock */
> static void unregister_trace_probe(struct trace_probe *tp)
> {
> @@ -1512,30 +1540,6 @@ partial:
> return TRACE_TYPE_PARTIAL_LINE;
> }
>
> -static int probe_event_enable(struct ftrace_event_call *call)
> -{
> - struct trace_probe *tp = (struct trace_probe *)call->data;
> -
> - tp->flags |= TP_FLAG_TRACE;
> - if (trace_probe_is_return(tp))
> - return enable_kretprobe(&tp->rp);
> - else
> - return enable_kprobe(&tp->rp.kp);
> -}
> -
> -static void probe_event_disable(struct ftrace_event_call *call)
> -{
> - struct trace_probe *tp = (struct trace_probe *)call->data;
> -
> - tp->flags &= ~TP_FLAG_TRACE;
> - if (!(tp->flags & (TP_FLAG_TRACE | TP_FLAG_PROFILE))) {
> - if (trace_probe_is_return(tp))
> - disable_kretprobe(&tp->rp);
> - else
> - disable_kprobe(&tp->rp.kp);
> - }
> -}
> -
> #undef DEFINE_FIELD
> #define DEFINE_FIELD(type, item, name, is_signed) \
> do { \
> @@ -1714,49 +1718,25 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
> head = this_cpu_ptr(call->perf_events);
> perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);
> }
> -
> -static int probe_perf_enable(struct ftrace_event_call *call)
> -{
> - struct trace_probe *tp = (struct trace_probe *)call->data;
> -
> - tp->flags |= TP_FLAG_PROFILE;
> -
> - if (trace_probe_is_return(tp))
> - return enable_kretprobe(&tp->rp);
> - else
> - return enable_kprobe(&tp->rp.kp);
> -}
> -
> -static void probe_perf_disable(struct ftrace_event_call *call)
> -{
> - struct trace_probe *tp = (struct trace_probe *)call->data;
> -
> - tp->flags &= ~TP_FLAG_PROFILE;
> -
> - if (!(tp->flags & TP_FLAG_TRACE)) {
> - if (trace_probe_is_return(tp))
> - disable_kretprobe(&tp->rp);
> - else
> - disable_kprobe(&tp->rp.kp);
> - }
> -}
> #endif /* CONFIG_PERF_EVENTS */
>
> static __kprobes
> int kprobe_register(struct ftrace_event_call *event, enum trace_reg type)
> {
> + struct trace_probe *tp = (struct trace_probe *)event->data;
> +
> switch (type) {
> case TRACE_REG_REGISTER:
> - return probe_event_enable(event);
> + return enable_trace_probe(tp, TP_FLAG_TRACE);
> case TRACE_REG_UNREGISTER:
> - probe_event_disable(event);
> + disable_trace_probe(tp, TP_FLAG_TRACE);
> return 0;
>
> #ifdef CONFIG_PERF_EVENTS
> case TRACE_REG_PERF_REGISTER:
> - return probe_perf_enable(event);
> + return enable_trace_probe(tp, TP_FLAG_PROFILE);
> case TRACE_REG_PERF_UNREGISTER:
> - probe_perf_disable(event);
> + disable_trace_probe(tp, TP_FLAG_PROFILE);
> return 0;
> #endif
> }




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