bpf: Allocate ID for bpf_link

Generate ID for each bpf_link using IDR, similarly to bpf_map and bpf_prog. bpf_link creation, initialization, attachment, and exposing to user-space through FD and ID is a complicated multi-step process, abstract it away through bpf_link_primer and bpf_link_prime(), bpf_link_settle(), and bpf_link_cleanup() internal API. They guarantee that until bpf_link is properly attached, user-space won't be able to access partially-initialized bpf_link either from FD or ID. All this allows to simplify bpf_link attachment and error handling code.

Andrii Nakryiko committed 6 years ago

Commit a3b80e11 parent f9d04124 files · +118 −57Browse files

Showing the changes to include/uapi/linux (1 of 4 files). Show all

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include/uapi/linux/bpf.h+1−0

@@ -523,6 +523,7 @@ union bpf_attr { · 522 unmodified lines
523	__u32 prog_id;	523	__u32 prog_id;
524	__u32 map_id;	524	__u32 map_id;
525	__u32 btf_id;	525	__u32 btf_id;
		526	__u32 link_id;
526	};	527	};
527	__u32 next_id;	528	__u32 next_id;
528	__u32 open_flags;	529	__u32 open_flags;