Re: [PATCH] kprobes: Print an error if probe is rejected

[Naveen N. Rao]

Hi Masami,

Masami Hiramatsu wrote:
> Hi Naveen,
>
> On Mon, 14 Jun 2021 21:00:52 +0530
> "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> wrote:
>
> > Steven Rostedt wrote:
> > > On Fri, 11 Jun 2021 19:25:38 +0530
> > > "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> wrote:
> > > 
> > >> We also have perf_event_open() as an interface to add probes, and I 
> > >> don't think it would be helpful to require all tools to utilize the 
> > >> error log from tracefs for this purpose.
> > > 
> > > The there should be a perf interface to read the errors. I agree with
> > > Masami. Let's not have console logs for probe errors.
> >
> > Ok, understood.
>
> Will you update this?

Not sure if you are asking about error logging with perf_event_open(), 
or about reading error_log from tracefs.

For perf_event_open(), I think we will just need to return the error 
code, and interpret the return value in userspace. I don't think there 
is any other way to pass error log or strings back from the kernel.

I will update this series to return the correct return value as 
suggested.


Thanks,
Naveen