On Thu, Jul 30, 2020 at 07:42:44PM -0700, Andrii Nakryiko wrote:
> The '&&' command seems to have a bad effect when $(cmd_$(1)) exits with
> non-zero effect: the command failure is masked (despite `set -e`) and all but
> the first command of $(dep-cmd) is executed (successfully, as they are mostly
> printfs), thus overall returning 0 in the end.
nice, thanks for digging into this,
any idea why is the failure masked?
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
jirka
>
> This means in practice that despite compilation errors, tools's build Makefile
> will return success. We see this very reliably with libbpf's Makefile, which
> doesn't get compilation error propagated properly. This in turns causes issues
> with selftests build, as well as bpftool and other projects that rely on
> building libbpf.
>
> The fix is simple: don't use &&. Given `set -e`, we don't need to chain
> commands with &&. The shell will exit on first failure, giving desired
> behavior and propagating error properly.
>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Fixes: 275e2d95591e ("tools build: Move dependency copy into function")
> Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> ---
>
> I'm sending this against bpf-next tree, given libbpf is affected enough for me
> to debug this fun problem that no one seemed to notice (or care, at least) in
> almost 5 years. If there is a better kernel tree, please let me know.
>
> tools/build/Build.include | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/build/Build.include b/tools/build/Build.include
> index 9ec01f4454f9..585486e40995 100644
> --- a/tools/build/Build.include
> +++ b/tools/build/Build.include
> @@ -74,7 +74,8 @@ dep-cmd = $(if $(wildcard $(fixdep)),
> # dependencies in the cmd file
> if_changed_dep = $(if $(strip $(any-prereq) $(arg-check)), \
> @set -e; \
> - $(echo-cmd) $(cmd_$(1)) && $(dep-cmd))
> + $(echo-cmd) $(cmd_$(1)); \
> + $(dep-cmd))
>
> # if_changed - execute command if any prerequisite is newer than
> # target, or command line has changed
> --
> 2.24.1
>
