Re: [PATCH] tracing/kprobes: Add trace event trigger invocations

From: Steven Rostedt
Date: Mon Jan 06 2014 - 11:11:00 EST


On Sat, 28 Dec 2013 20:24:08 -0600
Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx> wrote:

> Add code to the kprobe/kretprobe event functions that will invoke any
> event triggers associated with a probe's ftrace_event_file.
>
> The code to do this is very similar to the invocation code already
> used to invoke the triggers associated with static events and
> essentially replaces the existing soft-disable checks with a superset
> that preserves the original behavior but adds the bits needed to
> support event triggers.
>
> Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
> ---
> kernel/trace/trace_kprobe.c | 42 ++++++++++++++++++++++++++++++++++++------
> 1 file changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index dae9541..1ee13eb 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -812,12 +812,20 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
> struct ring_buffer *buffer;
> int size, dsize, pc;
> unsigned long irq_flags;
> + unsigned long eflags;
> + enum event_trigger_type __tt = ETT_NONE;

What's the significance of the "__" in the variable?

Looks as if you copied it from the ftrace_raw_event_* macro. The "__"
there is usually recommended because it is a macro and we try to avoid
namespace collisions by adding the "__".

This is a proper function, please remove the "__" from it.

Thanks,

-- Steve


> struct ftrace_event_call *call = &tp->call;
>
> WARN_ON(call != ftrace_file->event_call);
>
> - if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
> - return;
> + eflags = ftrace_file->flags;
> +
> + if (!(eflags & FTRACE_EVENT_FL_TRIGGER_COND)) {
> + if (eflags & FTRACE_EVENT_FL_TRIGGER_MODE)
> + event_triggers_call(ftrace_file, NULL);
> + if (eflags & FTRACE_EVENT_FL_SOFT_DISABLED)
> + return;
> + }
>
> local_save_flags(irq_flags);
> pc = preempt_count();
--
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