Re: kernel/bpf/verifier.c: 4 * possible unintended fallthrough ?

On Tue, Dec 20, 2016 at 3:20 AM, David Binderman [off-list ref] wrote:

Hello there,

I just tried to compile kernel-4.9 with a recent development
version of gcc. It said

kernel/bpf/verifier.c:1907:23: warning: this statement may fall through [-Wimplicit-fallthrough=]
kernel/bpf/verifier.c:1918:23: warning: this statement may fall through [-Wimplicit-fallthrough=]
kernel/bpf/verifier.c:1859:24: warning: this statement may fall through [-Wimplicit-fallthrough=]
kernel/bpf/verifier.c:1869:24: warning: this statement may fall through [-Wimplicit-fallthrough=]

Source code for the first one is

    case BPF_JGT:
        /* Unsigned comparison, the minimum value is 0. */
        true_reg->min_value = 0;
    case BPF_JSGT:

Suggest either add the missing break or document the fallthrough
with a comment something like /* FALLTHROUGH */

I've tried 4.9 and 5.2 and don't see this warning.
Is this 6.x gcc?
I suspect it will have such warnings all over the kernel.