Re: [PATCH v6 10/21] tracing: probeevent: Return consumed bytes of dynamic area

Masami Hiramatsu
2018-04-03T14:41:58Z

On Mon, 2 Apr 2018 16:02:07 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Sat, 17 Mar 2018 21:44:52 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > -static nokprobe_inline void
> > -fetch_store_string(unsigned long addr, void *dest)
> > +static nokprobe_inline int
> > +fetch_store_string(unsigned long addr, void *dest, void *base)
> > {
> > - int maxlen = get_rloc_len(*(u32 *)dest);
> > - u8 *dst = get_rloc_data(dest);
> > + int maxlen = get_loc_len(*(u32 *)dest);
> > + u8 *dst = get_loc_data(dest, base);
> > long ret;
> >
> > if (!maxlen)
> > - return;
> > + return -ENOMEM;
> >
> > /*
> > * Try to get string again, since the string can be changed while
> > @@ -854,19 +851,19 @@ fetch_store_string(unsigned long addr, void *dest)
> >
> > if (ret < 0) { /* Failed to fetch string */
> > dst[0] = '\0';
> > - *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
> > - } else {
> > - *(u32 *)dest = make_data_rloc(ret, get_rloc_offs(*(u32 *)dest));
> > + ret = 0;
>
> Why do you return 0 here and not the error value? You return -ENOMEM
> above if maxlen is zero.

Good catch! it should clear dst[0] and return 0 even if no buffer remains...
OK, I'll fix it.

Thank you!

>
> -- Steve
>
> > }
> > + *(u32 *)dest = make_data_loc(ret, (void *)dst - base);
> > + return ret;
> > }

--
Masami Hiramatsu <mhiramat@kernel.org>