Re: [PATCH] selftests/rseq: Fix circular dependencies in Makefile

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

On 2026-08-18 11:53, Mahad Ibrahim wrote:
> TEST_GEN_PROGS_EXTENDED lists the binaries which are to be built but not
> run. However it is also listed as prerequisite for every generated binary
> to link against; all binaries only require librseq.so.
> 
> This results in the following warnings:
> 
>    make: Circular .../rseq/check_optimized <- .../rseq/check_optimized dependency dropped.
> 
> Such warnings are emitted 36 times in in-tree and out-of-tree builds.
> 
> Additionally, the generation of a single binary pulls in all of
> TEST_GEN_PROGS_EXTENDED as they are listed as prerequisites for each
> other. However since Make drops all the prerequisites which form a cycle,
> the build succeeds, but results in unintended behavior. For example
> building a single binary like check_optimized compiles 9 binaries while
> only 2 are required.
> 
> Fix circular dependencies and unnecessary compilation of binaries in rseq
> Makefile by isolating librseq.so and headers into a single variable which
> is added as the prerequisite.
> 
> No warnings are emitted after the change, and building a single binary
> only compiles that binary and librseq.so. Verified in-tree and with
> OUTPUT= set to a separate directory.

Adding Michael in CC.

Thanks,

Mathieu

> 
> Fixes: cb48828f06af ("selftests/rseq: Don't run tests with runner scripts outside of the scripts")
> Signed-off-by: Mahad Ibrahim <mahad.ibrahim.dev@gmail.com>
> ---
>   tools/testing/selftests/rseq/Makefile | 28 ++++++++++++---------------
>   1 file changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/tools/testing/selftests/rseq/Makefile b/tools/testing/selftests/rseq/Makefile
> index aba6317f6cb8..9c369e59bb2d 100644
> --- a/tools/testing/selftests/rseq/Makefile
> +++ b/tools/testing/selftests/rseq/Makefile
> @@ -37,41 +37,37 @@ TEST_FILES := settings
>   
>   include ../lib.mk
>   
> +RSEQ_DEPS := $(OUTPUT)/librseq.so rseq.h rseq-*.h
> +
>   $(OUTPUT)/librseq.so: rseq.c rseq.h rseq-*.h
>   	$(CC) $(CFLAGS) -shared -fPIC $< $(LDLIBS) -o $@
>   
> -$(OUTPUT)/%: %.c $(TEST_GEN_PROGS_EXTENDED) rseq.h rseq-*.h
> +$(OUTPUT)/%: %.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/basic_percpu_ops_mm_cid_test: basic_percpu_ops_test.c $(TEST_GEN_PROGS_EXTENDED) rseq.h rseq-*.h
> +$(OUTPUT)/basic_percpu_ops_mm_cid_test: basic_percpu_ops_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DBUILDOPT_RSEQ_PERCPU_MM_CID $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/param_test_benchmark: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/param_test_benchmark: param_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DBENCHMARK $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/param_test_compare_twice: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/param_test_compare_twice: param_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DRSEQ_COMPARE_TWICE $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/param_test_mm_cid: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/param_test_mm_cid: param_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DBUILDOPT_RSEQ_PERCPU_MM_CID $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/param_test_mm_cid_benchmark: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/param_test_mm_cid_benchmark: param_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DBUILDOPT_RSEQ_PERCPU_MM_CID -DBENCHMARK $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/param_test_mm_cid_compare_twice: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/param_test_mm_cid_compare_twice: param_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) -DBUILDOPT_RSEQ_PERCPU_MM_CID -DRSEQ_COMPARE_TWICE $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/syscall_errors_test: syscall_errors_test.c $(TEST_GEN_PROGS_EXTENDED) \
> -					rseq.h rseq-*.h
> +$(OUTPUT)/syscall_errors_test: syscall_errors_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/slice_test: slice_test.c $(TEST_GEN_PROGS_EXTENDED) rseq.h rseq-*.h
> +$(OUTPUT)/slice_test: slice_test.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) $< $(LDLIBS) -lrseq -o $@
>   
> -$(OUTPUT)/check_optimized: check_optimized.c $(TEST_GEN_PROGS_EXTENDED) rseq.h rseq-*.h
> +$(OUTPUT)/check_optimized: check_optimized.c $(RSEQ_DEPS)
>   	$(CC) $(CFLAGS) $< $(LDLIBS) -lrseq -o $@
> 
> base-commit: 0f23d56f17fdfc7db69d51f64c8b91bbab947aa9


-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com