libbpf: Make kernel feature probing lazy

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Turn libbpf's kernel feature probing into lazily-performed checks. This allows
to skip performing unnecessary feature checks, if a given BPF application
doesn't rely on a particular kernel feature. As we grow number of feature
probes, libbpf might perform less unnecessary syscalls and scale better with
number of feature probes long-term.

By decoupling feature checks from bpf_object, it's also possible to perform
feature probing from libbpf static helpers and low-level APIs, if necessary.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200818213356.2629020-3-andriin@fb.com

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Andrii Nakryiko 2020-08-18 14:33:51 -07:00 • committed by Alexei Starovoitov

parent 8d70823605

commit 47b6cb4d0a

1 changed files with 86 additions and 64 deletions

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tools/lib/bpf/libbpf.c

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