2018-03-21 10:07 GMT+09:00 Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>:
> On Tue, 20 Mar 2018, Thomas Lindroth wrote:
>
>> On 03/20/2018 04:16 PM, Masahiro Yamada wrote:
>> >> 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@xxxxxxxxx>
>> >> Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
>> >>
>> >> diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
>> >> index 513da1a4a2..d67830e6e3 100755
>> >> --- 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}
>> >
>> >
>> > Does this patch solve your problem?
>> > I guess so, but I want you to test it just in case.
>>
>> Yes, it solves the build problem but I'm still experiencing the original
>> problem with vfio forwarded pci device even with this patch.
>
> All this patch pretends to do is fix the build race issue.
> So it should probably be applied for that reason alone.
I agree.
Applied to linux-kbuild/fixes. Thanks!
--
Best Regards
Masahiro Yamada
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