4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicolas Pitre nicolas.pitre@linaro.org
[ Upstream commit 825d487583089f9a33d31650c9c41f6474aab7fc ]
Some filesystems have timestamps with coarse precision that may allow for a recently built object file to have the same timestamp as the updated time on one of its dependency files. When that happens, the object file doesn't get rebuilt as it should.
This is especially the case on filesystems that don't have sub-second time precision, such as ext3 or Ext4 with 128B inodes.
Let's prevent that by making sure updated dependency files have a newer timestamp than the first file we created (i.e. autoksyms.h.tmpnew).
Reported-by: Thomas Lindroth thomas.lindroth@gmail.com Signed-off-by: Nicolas Pitre nico@linaro.org Tested-by: Thomas Lindroth thomas.lindroth@gmail.com Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- scripts/adjust_autoksyms.sh | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/scripts/adjust_autoksyms.sh +++ b/scripts/adjust_autoksyms.sh @@ -84,6 +84,13 @@ while read sympath; do depfile="include/config/ksym/${sympath}.h" mkdir -p "$(dirname "$depfile")" touch "$depfile" + # Filesystems with coarse time precision may create timestamps + # equal to the one from a file that was very recently built and that + # needs to be rebuild. Let's guard against that by making sure our + # dep files are always newer than the first file we created here. + while [ ! "$depfile" -nt "$new_ksyms_file" ]; do + touch "$depfile" + done echo $((count += 1)) done | tail -1 ) changed=${changed:-0}