On Tue, Oct 26, 2021 at 09:38:19PM +0800, Hou Tao wrote:
> An extra newline will output for bpf_log() with BPF_LOG_KERNEL level
> as shown below:
>
> [ 52.095704] BPF:The function test_3 has 12 arguments. Too many.
> [ 52.095704]
> [ 52.096896] Error in parsing func ptr test_3 in struct bpf_dummy_ops
>
> Now all bpf_log() are ended by newline, so just remove the extra newline.
bpf_verifier_vlog is also called by btf_verifier_log.
Not all of them is ended with newline.
>
> Also there is no need to calculate the left userspace buffer size
> for kernel log output and to truncate the output by '\0' which
> has already been done by vscnprintf(), so only do these for
> userspace log output.
>
> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
> ---
> kernel/bpf/verifier.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index c6616e325803..7d4a313da86e 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -299,13 +299,13 @@ void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
> WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
> "verifier log line truncated - local buffer too short\n");
>
> - n = min(log->len_total - log->len_used - 1, n);
> - log->kbuf[n] = '\0';
> -
> if (log->level == BPF_LOG_KERNEL) {
> - pr_err("BPF:%s\n", log->kbuf);
> + pr_err("BPF:%s", log->kbuf);
How about trim the tailing '\n' (if any) from kbuf?
or just test if kbuf is ended with '\n'?
> return;
> }
> +
> + n = min(log->len_total - log->len_used - 1, n);
> + log->kbuf[n] = '\0';
> if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
> log->len_used += n;
> else
> --
> 2.29.2
>
