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

Steven Rostedt
2018-04-02T20:02:11Z

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.

-- Steve

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