Re: [PATCH] bpf: fix a warning message in mark_ptr_not_null_reg()

[KP Singh]

On Tue, Feb 16, 2021 at 8:37 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> The WARN_ON() argument is a condition, and it generates a stack trace
> but it doesn't print the warning.
>
> Fixes: 4ddb74165ae5 ("bpf: Extract nullable reg type conversion into a helper function")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
>  kernel/bpf/verifier.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 056df6be3e30..bd4d1dfca73c 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -1120,7 +1120,7 @@ static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
>                 reg->type = PTR_TO_RDWR_BUF;
>                 break;
>         default:
> -               WARN_ON("unknown nullable register type");
> +               WARN(1, "unknown nullable register type");

Should we use WARN_ONCE here? Also, I think the fix should be targeted
for bpf-next as
the patch that introduced this hasn't made it to bpf yet.

[...]