path: root/scripts/Kbuild.include
diff options
authorMasahiro Yamada <yamada.masahiro@socionext.com>2018-11-30 10:05:22 +0900
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-12-01 23:13:14 +0900
commit392885ee82d35d515ba2af7b72c5e357c3002113 (patch)
tree88cc2f3fe6b0638845a1acda265f9bd38f2426ba /scripts/Kbuild.include
parentkbuild: descend into scripts/gcc-plugins/ via scripts/Makefile (diff)
kbuild: let fixdep directly write to .*.cmd files
Currently, fixdep writes dependencies to .*.tmp, which is renamed to .*.cmd after everything succeeds. This is a very safe way to avoid corrupted .*.cmd files. The if_changed_dep has carried this safety mechanism since it was added in 2002. If fixdep fails for some reasons or a user terminates the build while fixdep is running, the incomplete output from the fixdep could be troublesome. This is my insight about some bad scenarios: [1] If the compiler succeeds to generate *.o file, but fixdep fails to write necessary dependencies to .*.cmd file, Make will miss to rebuild the object when headers or CONFIG options are changed. In this case, fixdep should not generate .*.cmd file at all so that 'arg-check' will surely trigger the rebuild of the object. [2] A partially constructed .*.cmd file may not be a syntactically correct makefile. The next time Make runs, it would include it, then fail to parse it. Once this happens, 'make clean' is be the only way to fix it. In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special target"). Make deletes a target file on any failure in its recipe. Because fixdep is a part of the recipe of *.o target, if it fails, the *.o is deleted anyway. However, I am a bit worried about the slight possibility of [2]. So, here is a solution. Let fixdep directly write to a .*.cmd file, but allow makefiles to include it only when its corresponding target exists. This effectively reverts commit 2982c953570b ("kbuild: remove redundant $(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75 ("kbuild: remove dead code in cmd_files calculation in top Makefile") because now we must check the presence of targets. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'scripts/Kbuild.include')
1 files changed, 4 insertions, 6 deletions
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index bb015551c2d9..6cf6a8b83b97 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -264,9 +264,8 @@ ifndef CONFIG_TRIM_UNUSED_KSYMS
cmd_and_fixdep = \
$(echo-cmd) $(cmd_$(1)); \
- scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
- rm -f $(depfile); \
- mv -f $(dot-target).tmp $(dot-target).cmd;
+ scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).cmd;\
+ rm -f $(depfile);
@@ -289,9 +288,8 @@ cmd_and_fixdep = \
$(echo-cmd) $(cmd_$(1)); \
$(ksym_dep_filter) | \
scripts/basic/fixdep -e $(depfile) $@ '$(make-cmd)' \
- > $(dot-target).tmp; \
- rm -f $(depfile); \
- mv -f $(dot-target).tmp $(dot-target).cmd;
+ > $(dot-target).cmd; \
+ rm -f $(depfile);