program, btf: probe correct log buffer size #1500
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For some reason the Action decided to break now, after being updated a couple of weeks ago. Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
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florianl
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Jul 3, 2024
dylandreimerink
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Jul 3, 2024
The kernel exposes a log of operations to aid debugging a program
or BTF load. Until recently there was no way to know the size of
that buffer, so the library forces the user to specify a buffer
size. From a cursory survey on sourcegraph.com it seems that
users either hardcode a large fixed buffer or probe the correct
size by doubling the buffer size when hitting ENOSPC.
Since commit 47a71c1f9af0 ("bpf: Add log_true_size output field
to return necessary log buffer size") the kernel does provide a
hint to user space.
Move probing of the correct log buffer size into the library. On
recent (>= 6.4) kernels this is guaranteed to work in a single
call. On older kernels we use the doubling strategy employed by
cilium and tetragon.
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
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ci: fix golangci-lint
program, btf: probe correct log buffer size