Dne 14. 02. 24 v 14:36 Masahiro Yamada napsal(a):
On Wed, Feb 14, 2024 at 6:43 PM Radek Krejci <radek.krejci@xxxxxxxxxx> wrote:
Hi,
I've found a bug in modpost - when it gets the list of source files to
generate srcversion hash, it skips all the source/dependency files
except for the first one.
There is patch [1] in v5.8rc1 replacing get_next_line() by get_line() in
parse_source_file() function. Besides other things, the difference
between those 2 functions is that get_next_line() trims the leading
spaces of the line being returned. The issue is, that the source (deps_
located at the same directory) file names in the list, being processed
in parse_source_file(), are indented. So, when the code gets to
"Terminate line at first space, to get rid of final ' \'", it
effectively hides the source file name from further processing, since
the first space is at the beginning of the line.
I checked this behavior with modpost from v5.4 and v5.14 (and confirmed
with the current master in git). In my case, my kernel module had just 2
source files - mymodule.c and mymodule.h (both located at the same
directory). With modpost from v5.4, the code change in any of the files
was reflected in srcversion hash. But with modpost from v5.14 (and
master) there is no hash change when the code change appears in the
header file, which is listed at the end of the deps_ list. I believe
this is quite simple to reproduce with any module, but if needed, I can
prepare some example code to reproduce the issue.
Thanks. You are right.
I noticed this [2] email thread in the list. It mentions a similar
issue. However, since it happened a half year before the change [1] was
introduced and because I was unable to find any further details,
including the promised patch, I believe that these 2 things are unrelated.
Correct. They are different things.
Parsing the headers located in the same directory seems
to be a design.
The enclosed patch worked for me, but there might be some other
consequences that I've missed, so feel free to modify it on your own or
let me know.
Is there anything else I can do to help fixing this issue?
I think the attached patch is correct.
I will pick it up later.
One question is, is this feature still used?
I assume the answer is yes because you noticed this bug.
(but you are the first/only person who noticed it
in the past 3 years)
I was also surprised that no one noticed so far. Maybe my use case is
somehow specific - I wasn't able to use the module's version (not
maintained by the module authors), so the srcversion was the way how to
check that the loaded module is the one I expect. And surprisingly, with
the same source files, the expected hash changed between kernels v5.4
and v5.14.
Thanks,
Radek
Thanks.
Regards,
Radek Krejci
[1] -
https://urldefense.com/v3/__https://lore.kernel.org/linux-kbuild/20200601055731.3006266-26-masahiroy@xxxxxxxxxx/__;!!ACWV5N9M2RV99hQ!LR5KEN-WVLtWxWk3vtaqPD9DwmpPPIwMFle61qi8b83V1SGdNbFydDDQ_DGJ_bUmjM6Z6NgkH4NuxliZewmIkA$
[2] -
https://urldefense.com/v3/__https://lore.kernel.org/linux-kbuild/CAN19L9G-mFN-MTmw0FS3ZX4d1MjeoL2U*s-Fk7Qw9UYWn5Q1YA@xxxxxxxxxxxxxx/__;Kw!!ACWV5N9M2RV99hQ!LR5KEN-WVLtWxWk3vtaqPD9DwmpPPIwMFle61qi8b83V1SGdNbFydDDQ_DGJ_bUmjM6Z6NgkH4Nuxlga4dF0SA$
--
Best Regards
Masahiro Yamada
