tools: ynl-gen: don't touch the output file if content is the same
I often regenerate all YNL files in the tree to make sure they
are in sync with the codegen and specs. Generator rewrites
the files unconditionally, so since make looks at file modification
time to decide what to rebuild - my next build takes longer.
We already generate the code to a tempfile most of the time,
only overwrite the target when we have to.
Before:
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:19:56.
347071940 -0700
Modify: 2023-10-27 15:19:45.
089000900 -0700
Change: 2023-10-27 15:19:45.
089000900 -0700
Birth: 2023-10-27 15:19:45.
088000894 -0700
$ ./tools/net/ynl/ynl-regen.sh -f
[...]
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:19:56.
347071940 -0700
Modify: 2023-10-27 15:22:18.
417968446 -0700
Change: 2023-10-27 15:22:18.
417968446 -0700
Birth: 2023-10-27 15:19:45.
088000894 -0700
After:
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:22:41.
520114221 -0700
Modify: 2023-10-27 15:22:18.
417968446 -0700
Change: 2023-10-27 15:22:18.
417968446 -0700
Birth: 2023-10-27 15:19:45.
088000894 -0700
$ ./tools/net/ynl/ynl-regen.sh -f
[...]
$ stat include/uapi/linux/netdev.h
File: include/uapi/linux/netdev.h
Size: 2307 Blocks: 8 IO Block: 4096 regular file
Access: 2023-10-27 15:22:41.
520114221 -0700
Modify: 2023-10-27 15:22:18.
417968446 -0700
Change: 2023-10-27 15:22:18.
417968446 -0700
Birth: 2023-10-27 15:19:45.
088000894 -0700
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231027223408.1865704-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
projects / linux.git / commit