On Mon, Jan 20, 2020 at 5:08 AM Toke Høiland-Jørgensen [off-list ref] wrote:

From: Toke Høiland-Jørgensen <redacted>

The runqslower tool refuses to build without a file to read vmlinux BTF
from. The build fails with an error message to override the location by
setting the VMLINUX_BTF variable if autodetection fails. However, the
Makefile doesn't actually work with that override - the error message is
still emitted.

Fix this by including the value of VMLINUX_BTF in the expansion, and only
emitting the error message if the *result* is empty. Also permit running
'make clean' even though no VMLINUX_BTF is set.

Fixes: 9c01546d26d2 ("tools/bpf: Add runqslower tool to tools/bpf")
Signed-off-by: Toke Høiland-Jørgensen <redacted>
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Thanks!

Acked-by: Andrii Nakryiko <redacted>

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