diff mbox series

[bpf-next,2/2] selftests/bpf: set vpath in Makefile to search for skels

Message ID 20240916195919.1872371-2-ihor.solodrai@pm.me (mailing list archive)
State New
Delegated to: BPF
Headers show
Series [bpf-next,1/2] selftests/bpf: remove test_skb_cgroup_id.sh from TEST_PROGS | expand

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Commit Message

Ihor Solodrai Sept. 16, 2024, 7:59 p.m. UTC 
Auto-dependencies generated for %.test.o files refer to skels using
filenames as opposed to full paths. This requires make to be able to
link this name to an actual path, because not all generated skels are
put in the working directory.

In the original patch [1], this was mitigated by this target:

$(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h
	@true

This turned out to be insufficient.

First, %.lskel.h and %.subskel.h were missed, because a typical
selftests/bpf build could find these files in the working directory.
This error was detected by an out-of-tree build [2].

Second, even with missing rules added, this target causes unnecessary
rebuilds in the out-of-tree case, as X.skel.h is searched for in the
working directory, and not in the $(OUTPUT).

Using vpath directive [3] is a better solution. Instead of introducing
a separate target (X.skel.h in addition to $(TRUNNER_OUTPUT)/X.skel.h),
make is instructed to search for skels in the output, which allows make
to correctly detect that skel has already been generated.

[1]: https://lore.kernel.org/bpf/VJihUTnvtwEgv_mOnpfy7EgD9D2MPNoHO-MlANeLIzLJPGhDeyOuGKIYyKgk0O6KPjfM-MuhtvPwZcngN8WFqbTnTRyCSMc2aMZ1ODm1T_g=@pm.me/
[2]: https://lore.kernel.org/bpf/CIjrhJwoIqMc2IhuppVqh4ZtJGbx8kC8rc9PHhAIU6RccnWT4I04F_EIr4GxQwxZe89McuGJlCnUk9UbkdvWtSJjAsd7mHmnTy9F8K2TLZM=@pm.me/
[3]: https://www.gnu.org/software/make/manual/html_node/Selective-Search.html

Reported-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>
---
 tools/testing/selftests/bpf/Makefile | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

Comments

Ihor Solodrai Sept. 16, 2024, 8:11 p.m. UTC | #1 
On Monday, September 16th, 2024 at 12:59 PM, Ihor Solodrai <ihor.solodrai@pm.me> wrote:

[...]

> ---
> tools/testing/selftests/bpf/Makefile | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index df75f1beb731..365740f24d2e 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -622,10 +622,11 @@ $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_OUTPUT)/%: $$$$(%-deps) $(BPFTOOL) | $(TR
> 
> # When the compiler generates a %.d file, only skel basenames (not
> # full paths) are specified as prerequisites for corresponding %.o
> -# file. This target makes %.skel.h basename dependent on full paths,
> -# linking generated %.d dependency with actual %.skel.h files.
> -$(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h
> - @true
> +# file. vpath directives below instruct make to search for skel files
> +# in TRUNNER_OUTPUT, if they are not present in the working directory.
> +vpath %.skel.h $(TRUNNER_OUTPUT)
> +vpath %.lskel.h $(TRUNNER_OUTPUT)
> +vpath %.subskel.h $(TRUNNER_OUTPUT)
> 
> endif
> 
> --
> 2.34.1

Hi Björn.

It'd be great if you could confirm that this patch works for your
use-case.

Regarding unnecessary rebuilds, you will still see some skels and
bpf.o objects rebuilt on out-of-tree builds. These are related to
$(LINKED_SKELS) in selftests/bpf/Makefile. They are entangled with
%-deps variables, and I couldn't come up with a similar solution for
them quickly. However, there are just a couple of them, and the
rebuild is relatively fast, so I decided to submit a patch that fixes
most of the problem.

Thank you!
Eduard Zingerman Sept. 17, 2024, 4 a.m. UTC | #2 
On Mon, 2024-09-16 at 19:59 +0000, Ihor Solodrai wrote:

[...]

> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index df75f1beb731..365740f24d2e 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -622,10 +622,11 @@ $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_OUTPUT)/%: $$$$(%-deps) $(BPFTOOL) | $(TR
>  
>  # When the compiler generates a %.d file, only skel basenames (not
>  # full paths) are specified as prerequisites for corresponding %.o
> -# file. This target makes %.skel.h basename dependent on full paths,
> -# linking generated %.d dependency with actual %.skel.h files.
> -$(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h
> -	@true
> +# file. vpath directives below instruct make to search for skel files
> +# in TRUNNER_OUTPUT, if they are not present in the working directory.
> +vpath %.skel.h $(TRUNNER_OUTPUT)
> +vpath %.lskel.h $(TRUNNER_OUTPUT)
> +vpath %.subskel.h $(TRUNNER_OUTPUT)
>  
>  endif

When I try this patch, the following happens after first full tests build:

$ touch progs/verifier_and.c; make -j test_progs

  CLNG-BPF [test_progs] verifier_and.bpf.o
  CLNG-BPF [test_progs-no_alu32] verifier_and.bpf.o
  CLNG-BPF [test_progs-cpuv4] verifier_and.bpf.o
  GEN-SKEL [test_progs] verifier_and.skel.h
  GEN-SKEL [test_progs-no_alu32] verifier_and.skel.h
  GEN-SKEL [test_progs-cpuv4] verifier_and.skel.h
  TEST-OBJ [test_progs] verifier.test.o
  BINARY   test_progs

Note that multiple binaries are built.
Björn Töpel Sept. 17, 2024, 8:53 a.m. UTC | #3 
Ihor Solodrai <ihor.solodrai@pm.me> writes:

> Auto-dependencies generated for %.test.o files refer to skels using
> filenames as opposed to full paths. This requires make to be able to
> link this name to an actual path, because not all generated skels are
> put in the working directory.
>
> In the original patch [1], this was mitigated by this target:
>
> $(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h
> 	@true
>
> This turned out to be insufficient.
>
> First, %.lskel.h and %.subskel.h were missed, because a typical
> selftests/bpf build could find these files in the working directory.
> This error was detected by an out-of-tree build [2].
>
> Second, even with missing rules added, this target causes unnecessary
> rebuilds in the out-of-tree case, as X.skel.h is searched for in the
> working directory, and not in the $(OUTPUT).
>
> Using vpath directive [3] is a better solution. Instead of introducing
> a separate target (X.skel.h in addition to $(TRUNNER_OUTPUT)/X.skel.h),
> make is instructed to search for skels in the output, which allows make
> to correctly detect that skel has already been generated.
>
> [1]: https://lore.kernel.org/bpf/VJihUTnvtwEgv_mOnpfy7EgD9D2MPNoHO-MlANeLIzLJPGhDeyOuGKIYyKgk0O6KPjfM-MuhtvPwZcngN8WFqbTnTRyCSMc2aMZ1ODm1T_g=@pm.me/
> [2]: https://lore.kernel.org/bpf/CIjrhJwoIqMc2IhuppVqh4ZtJGbx8kC8rc9PHhAIU6RccnWT4I04F_EIr4GxQwxZe89McuGJlCnUk9UbkdvWtSJjAsd7mHmnTy9F8K2TLZM=@pm.me/
> [3]: https://www.gnu.org/software/make/manual/html_node/Selective-Search.html
>
> Reported-by: Björn Töpel <bjorn@kernel.org>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>

As you point out, there are rebuilds triggered for the bpf "install"
target. Now rebuild are better than failures. Thanks for the fix!

Tested-by: Björn Töpel <bjorn@rivosinc.com>
Ihor Solodrai Sept. 17, 2024, 3:04 p.m. UTC | #4 
On Monday, September 16th, 2024 at 9:00 PM, Eduard Zingerman <eddyz87@gmail.com> wrote:

[...]

> 
> When I try this patch, the following happens after first full tests build:
> 
> $ touch progs/verifier_and.c; make -j test_progs
> 
> CLNG-BPF [test_progs] verifier_and.bpf.o
> CLNG-BPF [test_progs-no_alu32] verifier_and.bpf.o
> CLNG-BPF [test_progs-cpuv4] verifier_and.bpf.o
> GEN-SKEL [test_progs] verifier_and.skel.h
> GEN-SKEL [test_progs-no_alu32] verifier_and.skel.h
> GEN-SKEL [test_progs-cpuv4] verifier_and.skel.h
> TEST-OBJ [test_progs] verifier.test.o
> BINARY test_progs
> 
> Note that multiple binaries are built.

Eduard, I've just tried on master (without this patch)

    $ touch progs/verifier_and.c; make -j test_progs

and I get a similar sequence:

    CLNG-BPF [test_progs] verifier_and.bpf.o
    GEN-SKEL [test_progs] verifier_and.skel.h
    CLNG-BPF [test_progs-cpuv4] verifier_and.bpf.o
    GEN-SKEL [test_progs-cpuv4] verifier_and.skel.h
    CLNG-BPF [test_progs-no_alu32] verifier_and.bpf.o
    GEN-SKEL [test_progs-no_alu32] verifier_and.skel.h
    TEST-OBJ [test_progs] verifier.test.o
    BINARY   test_progs
    TEST-OBJ [test_progs-no_alu32] verifier.test.o
    EXT-COPY [test_progs-no_alu32] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c
    BINARY   test_progs-no_alu32
    TEST-OBJ [test_progs-cpuv4] verifier.test.o
    EXT-COPY [test_progs-cpuv4] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c
    BINARY   test_progs-cpuv4


%.bpf.o -> %.skel.h -> %.test.o have to be built for each TRUNNER,
right? And then each TRUNNER needs to be rebuilt because of %.test.o
change. Using vpath for skels doesn't change this behavior.

Maybe I'm missing something, let me know.
Eduard Zingerman Sept. 17, 2024, 5:53 p.m. UTC | #5 
On Tue, 2024-09-17 at 15:04 +0000, Ihor Solodrai wrote:

[...]

> Eduard, I've just tried on master (without this patch)
> 
>     $ touch progs/verifier_and.c; make -j test_progs
> 
> and I get a similar sequence:
> 
>     CLNG-BPF [test_progs] verifier_and.bpf.o
>     GEN-SKEL [test_progs] verifier_and.skel.h
>     CLNG-BPF [test_progs-cpuv4] verifier_and.bpf.o
>     GEN-SKEL [test_progs-cpuv4] verifier_and.skel.h
>     CLNG-BPF [test_progs-no_alu32] verifier_and.bpf.o
>     GEN-SKEL [test_progs-no_alu32] verifier_and.skel.h
>     TEST-OBJ [test_progs] verifier.test.o
>     BINARY   test_progs
>     TEST-OBJ [test_progs-no_alu32] verifier.test.o
>     EXT-COPY [test_progs-no_alu32] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c
>     BINARY   test_progs-no_alu32
>     TEST-OBJ [test_progs-cpuv4] verifier.test.o
>     EXT-COPY [test_progs-cpuv4] urandom_read bpf_testmod.ko bpf_test_no_cfi.ko liburandom_read.so xdp_synproxy sign-file uprobe_multi ima_setup.sh verify_sig_setup.sh btf_dump_test_case_bitfields.c btf_dump_test_case_multidim.c btf_dump_test_case_namespacing.c btf_dump_test_case_ordering.c btf_dump_test_case_packing.c btf_dump_test_case_padding.c btf_dump_test_case_syntax.c
>     BINARY   test_progs-cpuv4
> 
> 
> %.bpf.o -> %.skel.h -> %.test.o have to be built for each TRUNNER,
> right? And then each TRUNNER needs to be rebuilt because of %.test.o
> change. Using vpath for skels doesn't change this behavior.
> 
> Maybe I'm missing something, let me know.
> 

Hm, right, sorry for the noise.
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index df75f1beb731..365740f24d2e 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -622,10 +622,11 @@  $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_OUTPUT)/%: $$$$(%-deps) $(BPFTOOL) | $(TR
 
 # When the compiler generates a %.d file, only skel basenames (not
 # full paths) are specified as prerequisites for corresponding %.o
-# file. This target makes %.skel.h basename dependent on full paths,
-# linking generated %.d dependency with actual %.skel.h files.
-$(notdir %.skel.h): $(TRUNNER_OUTPUT)/%.skel.h
-	@true
+# file. vpath directives below instruct make to search for skel files
+# in TRUNNER_OUTPUT, if they are not present in the working directory.
+vpath %.skel.h $(TRUNNER_OUTPUT)
+vpath %.lskel.h $(TRUNNER_OUTPUT)
+vpath %.subskel.h $(TRUNNER_OUTPUT)
 
 endif