From 7cb779a6867fea00b4209bcf6de2f178a743247d Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Mon, 11 Sep 2023 12:47:30 -0700 Subject: bpf: Clarify error expectations from bpf_clone_redirect Commit 151e887d8ff9 ("veth: Fixing transmit return status for dropped packets") exposed the fact that bpf_clone_redirect is capable of returning raw NET_XMIT_XXX return codes. This is in the conflict with its UAPI doc which says the following: "0 on success, or a negative error in case of failure." Update the UAPI to reflect the fact that bpf_clone_redirect can return positive error numbers, but don't explicitly define their meaning. Reported-by: Daniel Borkmann Signed-off-by: Stanislav Fomichev Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20230911194731.286342-1-sdf@google.com --- include/uapi/linux/bpf.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 8790b3962e4b..0448700890f7 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1962,7 +1962,9 @@ union bpf_attr { * performed again, if the helper is used in combination with * direct packet access. * Return - * 0 on success, or a negative error in case of failure. + * 0 on success, or a negative error in case of failure. Positive + * error indicates a potential drop or congestion in the target + * device. The particular positive error codes are not defined. * * u64 bpf_get_current_pid_tgid(void) * Description -- cgit v1.2.3 From 8f908db77782630c45ba29dac35c434b5ce0b730 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Fri, 15 Sep 2023 10:34:27 -0700 Subject: bpf: Fix BTF_ID symbol generation collision Marcus and Satya reported an issue where BTF_ID macro generates same symbol in separate objects and that breaks final vmlinux link. ld.lld: error: ld-temp.o :14577:1: symbol '__BTF_ID__struct__cgroup__624' is already defined This can be triggered under specific configs when __COUNTER__ happens to be the same for the same symbol in two different translation units, which is already quite unlikely to happen. Add __LINE__ number suffix to make BTF_ID symbol more unique, which is not a complete fix, but it would help for now and meanwhile we can work on better solution as suggested by Andrii. Cc: stable@vger.kernel.org Reported-by: Satya Durga Srinivasu Prabhala Reported-by: Marcus Seyfarth Closes: https://github.com/ClangBuiltLinux/linux/issues/1913 Debugged-by: Nathan Chancellor Link: https://lore.kernel.org/bpf/CAEf4Bzb5KQ2_LmhN769ifMeSJaWfebccUasQOfQKaOd0nQ51tw@mail.gmail.com/ Signed-off-by: Jiri Olsa Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20230915-bpf_collision-v3-1-263fc519c21f@google.com Signed-off-by: Alexei Starovoitov --- include/linux/btf_ids.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h index a3462a9b8e18..a9cb10b0e2e9 100644 --- a/include/linux/btf_ids.h +++ b/include/linux/btf_ids.h @@ -49,7 +49,7 @@ word \ ____BTF_ID(symbol, word) #define __ID(prefix) \ - __PASTE(prefix, __COUNTER__) + __PASTE(__PASTE(prefix, __COUNTER__), __LINE__) /* * The BTF_ID defines unique symbol for each ID pointing -- cgit v1.2.3