[DTrace-devel] [PATCH 08/20] bpf: don't throw away CTF errors when doing relocations

[Kris Van Hees]

On Wed, May 11, 2022 at 10:12:50PM +0100, Nick Alcock via DTrace-devel wrote:
> The first type lookup done after translators are parsed is the set done
> to relocate CTF-related offsets.  If something is wrong with the CTF and
> the translators are missing, these lookups are likely to fail -- but
> since most of these lookups don't set dt_ctferr, the actual error is
> discarded and the only thing reported to the user is "unknown CTF
> error".  Not even CTF debugging helps.
> 
> Signed-off-by: Nick Alcock <nick.alcock at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

... and queued for dev

> ---
>  libdtrace/dt_cc.c | 23 ++++++++++++++---------
>  1 file changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
> index fba54cb02fdc..c6c31fc92712 100644
> --- a/libdtrace/dt_cc.c
> +++ b/libdtrace/dt_cc.c
> @@ -2380,10 +2380,10 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>  				ctf_file_t *cfp = dtp->dt_shared_ctf;
>  				ctf_id_t type = ctf_lookup_by_name(cfp, "struct task_struct");
>  				ctf_membinfo_t ctm;
> -				int rc;
> +				int rc = 0;
>  
>  				if (type == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  
>  				switch (idp->di_id) {
>  				case DT_CONST_TASK_PID:
> @@ -2400,7 +2400,7 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>  					break;
>  				}
>  				if (rc == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  				nrp->dofr_data = ctm.ctm_offset / NBBY;
>  				continue;
>  			}
> @@ -2411,11 +2411,12 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>  				ctf_id_t rc = CTF_ERR;
>  
>  				if (type == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  
>  				rc = ctf_member_info(cfp, type, "owner", &ctm);
>  				if (rc == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
> +
>  				nrp->dofr_data = ctm.ctm_offset / NBBY;
>  				continue;
>  			}
> @@ -2437,18 +2438,18 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>  
>  				type = ctf_lookup_by_name(cfp, "rwlock_t");
>  				if (type == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  				rc = ctf_member_info(cfp, type, "raw_lock", &ctm);
>  				if (rc == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  				total_offset = ctm.ctm_offset / NBBY;
>  
>  				type = ctf_lookup_by_name(cfp, "arch_rwlock_t");
>  				if (type == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  				rc = ctf_member_info(cfp, type, "cnts", &ctm);
>  				if (rc == CTF_ERR)
> -					return -1;
> +					goto err_ctf;
>  				total_offset += ctm.ctm_offset / NBBY;
>  
>  				nrp->dofr_data = total_offset;
> @@ -2497,6 +2498,10 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
>  	}
>  
>  	return pc;
> +
> + err_ctf:
> +	dtp->dt_ctferr = ctf_errno(dtp->dt_shared_ctf);
> +	return -1;
>  }
>  
>  static void
> -- 
> 2.36.1.263.g194b774378.dirty
> 
> 
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