Re: [PATCH v5 09/10] Uprobes/sdt: Document about reference counter

[Srikar Dronamraju]

* Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx> [2018-06-28 10:52:08]:

> Reference counter gate the invocation of probe. If present,
> by default reference count is 0. Kernel needs to increment
> it before tracing the probe and decrement it when done. This
> is identical to semaphore in Userspace Statically Defined
> Tracepoints (USDT).
> 
> Document usage of reference counter.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
> Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>

Unlike perf, this mechanism cannot detect ref count and depends on the
users data. What happens if the user mistakenly provides a wrong location?
I guess he can corrupt some other data structures?

Hence I would think twice of advertising this mechanism. i.e keep this
as an undocumented feature.