On Fri, May 14, 2021 at 8:37 AM kernel test robot <lkp@xxxxxxxxx> wrote:
> cppcheck possible warnings: (new ones prefixed by >>, may not real problems)
>
> >> kernel/bpf/helpers.c:713:43: warning: Uninitialized variable: bufs [uninitvar]
> if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(bufs->tmp_bufs))) {
> ^
I don't think this is a real problem. bufs is not actually
dereferenced, it is only used to give the type information to a
sizeof. This is only evaluated at compilation time.
If this matters, I guess we could silent this cppcheck warning with
something like the following patch. Alexei, what do you think ?
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -697,8 +697,9 @@ static int bpf_trace_copy_string(char *buf, void
*unsafe_ptr, char fmt_ptype,
#define MAX_PRINTF_BUF_LEN 512
/* Support executing three nested bprintf helper calls on a given CPU */
+#define MAX_PRINTF_NEST_LEVEL 3
struct bpf_bprintf_buffers {
- char tmp_bufs[3][MAX_PRINTF_BUF_LEN];
+ char tmp_bufs[MAX_PRINTF_NEST_LEVEL][MAX_PRINTF_BUF_LEN];
};
static DEFINE_PER_CPU(struct bpf_bprintf_buffers, bpf_bprintf_bufs);
static DEFINE_PER_CPU(int, bpf_bprintf_nest_level);
@@ -710,7 +711,7 @@ static int try_get_fmt_tmp_buf(char **tmp_buf)
preempt_disable();
nest_level = this_cpu_inc_return(bpf_bprintf_nest_level);
- if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(bufs->tmp_bufs))) {
+ if (WARN_ON_ONCE(nest_level > MAX_PRINTF_NEST_LEVEL)) {
this_cpu_dec(bpf_bprintf_nest_level);
preempt_enable();
return -EBUSY;
