Re: [PATCH 2/4] modpost: dump missing namespaces into a single modules.nsdeps file

[Jessica Yu]

+++ Masahiro Yamada [29/10/19 21:38 +0900]:
> The modpost, with the -d option given, generates per-module .ns_deps
> files.
>
> Kbuild generates per-module .mod files to carry module information.
> This is convenient because Make handles multiple jobs when the -j
> option is given.
>
> On the other hand, the modpost always runs as a single thread.
> I do not see a strong reason to produce separate .ns_deps files.
>
> This commit changes the modpost to generate just one file,
> modules.nsdeps, each line of which has the following format:
>
>  <module_name>: <list of missing namespaces>
>
> Please note it contains *missing* namespaces instead of required ones.
> So, modules.nsdeps is empty if the namespace dependency is all good.
>
> This will work more efficiently because spatch will no longer process
> already imported namespaces. I removed the '(if needed)' from the
> nsdeps log since spatch is invoked only when needed.
>
> This also solved the stale .ns_deps files problem reported by
> Jessica Yu:
>
>  https://lkml.org/lkml/2019/10/28/467
>
> While I was here, I improved the modpost code a little more;
> I freed ns_deps_bus.p because buf_write() allocates memory.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
>
> .gitignore               |  2 +-
> Documentation/dontdiff   |  1 +
> Makefile                 |  4 ++--
> scripts/Makefile.modpost |  2 +-
> scripts/mod/modpost.c    | 44 +++++++++++++++++-----------------------
> scripts/mod/modpost.h    |  4 ++--
> scripts/nsdeps           | 21 +++++++++----------
> 7 files changed, 36 insertions(+), 42 deletions(-)
>
> diff --git a/.gitignore b/.gitignore
> index 70580bdd352c..72ef86a5570d 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -32,7 +32,6 @@
> *.lzo
> *.mod
> *.mod.c
> -*.ns_deps
> *.o
> *.o.*
> *.patch
> @@ -61,6 +60,7 @@ modules.order
> /System.map
> /Module.markers
> /modules.builtin.modinfo
> +/modules.nsdeps
>
> #
> # RPM spec file (make rpm-pkg)
> diff --git a/Documentation/dontdiff b/Documentation/dontdiff
> index 9f4392876099..72fc2e9e2b63 100644
> --- a/Documentation/dontdiff
> +++ b/Documentation/dontdiff
> @@ -179,6 +179,7 @@ mkutf8data
> modpost
> modules.builtin
> modules.builtin.modinfo
> +modules.nsdeps
> modules.order
> modversions.h*
> nconf
> diff --git a/Makefile b/Makefile
> index 0ef897fd9cfd..1e3f307bd49b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1356,7 +1356,7 @@ endif # CONFIG_MODULES
>
> # Directories & files removed with 'make clean'
> CLEAN_DIRS  += include/ksym
> -CLEAN_FILES += modules.builtin.modinfo
> +CLEAN_FILES += modules.builtin.modinfo modules.nsdeps

Hmm, I tried to run `make -C path/to/kernel/src M=$(PWD) clean` for a test
external module, but it didn't remove modules.nsdeps for me. I declared a
MODULE namespace for testing purposes.

$ make 
make -C /dev/shm/linux M=/tmp/ppyu/test-module 
make[1]: Entering directory '/dev/shm/linux'
 AR      /tmp/ppyu/test-module/built-in.a
 CC [M]  /tmp/ppyu/test-module/test1.o
 CC [M]  /tmp/ppyu/test-module/test2.o
 LD [M]  /tmp/ppyu/test-module/test.o
 Building modules, stage 2.
 MODPOST 1 modules
WARNING: module test uses symbol try_module_get from namespace MODULE, but does not import it.
 CC [M]  /tmp/ppyu/test-module/test.mod.o
 LD [M]  /tmp/ppyu/test-module/test.ko
make[1]: Leaving directory '/dev/shm/linux'

Then I make nsdeps:

make -C /dev/shm/linux M=/tmp/ppyu/test-module nsdeps
make[1]: Entering directory '/dev/shm/linux'
 Building modules, stage 2.
 MODPOST 1 modules
WARNING: module test uses symbol try_module_get from namespace MODULE, but does not import it.
Adding namespace MODULE to module /tmp/ppyu/test-module/test.ko.
--- /tmp/ppyu/test-module/test1.c
+++ /tmp/cocci-output-3696-c1f8b3-test1.c
@@ -38,3 +38,4 @@ static void __exit hello_cleanup(void)
module_init(hello_init);
module_exit(hello_cleanup);
MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(MODULE);
make[1]: Leaving directory '/dev/shm/linux'
$ cat modules.nsdeps
/tmp/ppyu/test-module/test.ko: MODULE

Looks good so far, then I try make clean:

$ make clean
make -C /dev/shm/linux M=/tmp/ppyu/test-module clean
make[1]: Entering directory '/dev/shm/linux'
 CLEAN   /tmp/ppyu/test-module/Module.symvers
make[1]: Leaving directory '/dev/shm/linux'
$ ls
Makefile  modules.nsdeps  test1.c  test2.c

But modules.nsdeps is still there.