Re: [PATCH bpf-next v3 2/3] libbpf: add low level TC-BPF API

On 4/21/21 10:06 AM, Kumar Kartikeya Dwivedi wrote:

On Wed, Apr 21, 2021 at 12:28:01PM IST, Yonghong Song wrote:

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On 4/20/21 12:37 PM, Kumar Kartikeya Dwivedi wrote:

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This adds functions that wrap the netlink API used for adding,
manipulating, and removing traffic control filters. These functions
operate directly on the loaded prog's fd, and return a handle to the
filter using an out parameter named id.

The basic featureset is covered to allow for attaching and removal of
filters. Some additional features like TCA_BPF_POLICE and TCA_RATE for
the API have been omitted. These can added on top later by extending the

"later" => "layer"?

No, I meant that other options can be added on top of this series by someone
later. I'll reword it.

[...]

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Reviewed-by: Toke Høiland-Jørgensen <redacted>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
   tools/lib/bpf/libbpf.h   |  44 ++++++
   tools/lib/bpf/libbpf.map |   3 +
   tools/lib/bpf/netlink.c  | 319 ++++++++++++++++++++++++++++++++++++++-
   3 files changed, 360 insertions(+), 6 deletions(-)

diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index bec4e6a6e31d..b4ed6a41ea70 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h

@@ -16,6 +16,8 @@
   #include <stdbool.h>
   #include <sys/types.h>  // for size_t
   #include <linux/bpf.h>
+#include <linux/pkt_sched.h>
+#include <linux/tc_act/tc_bpf.h>
   #include "libbpf_common.h"

@@ -775,6 +777,48 @@ LIBBPF_API int bpf_linker__add_file(struct bpf_linker *linker, const char *filen
   LIBBPF_API int bpf_linker__finalize(struct bpf_linker *linker);
   LIBBPF_API void bpf_linker__free(struct bpf_linker *linker);
+/* Convenience macros for the clsact attach hooks */
+#define BPF_TC_CLSACT_INGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_INGRESS)
+#define BPF_TC_CLSACT_EGRESS TC_H_MAKE(TC_H_CLSACT, TC_H_MIN_EGRESS)
+
+struct bpf_tc_opts {
+	size_t sz;
+	__u32 handle;
+	__u32 class_id;
+	__u16 priority;
+	bool replace;
+	size_t :0;

Did you see any error without "size_t :0"?

Not really, I just added this considering this recent change:
dde7b3f5f2f4 ("libbpf: Add explicit padding to bpf_xdp_set_link_opts")

Thanks. That is fine with me then.

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+};
+
+#define bpf_tc_opts__last_field replace
+
+/* Acts as a handle for an attached filter */
+struct bpf_tc_attach_id {
+	__u32 handle;
+	__u16 priority;
+};
+

[...]

--
Kartikeya