From: Otto Moerbeek <o...@drijf.net>
Subject: Re: valgrind
Date: Wed, 16 Dec 2020 20:27:58 +0100
> On Wed, Dec 16, 2020 at 09:33:43AM +0100, Otto Moerbeek wrote:
>
>> On Mon, Dec 14, 2020 at 02:24:52PM +0900, Masato Asou wrote:
>>
>> > Hi,
>> >
>> > From: Otto Moerbeek <o...@drijf.net>
>> > Date: Fri, 11 Dec 2020 08:54:36 +0100
>> >
>> > > Hi,
>> > >
>> > > I did some basic testing of valgrind on amd64 and it seems to be in
>> > > better shape than before, at least for memory leak detection.
>> > >
>> > > But I do seem to get a report on every syscall done. One example:
>> > >
>> > > ==7218== Use of uninitialised value of size 8
>> > > ==7218== at 0x4A7670E: write (sys/w_write.c:28)
>> > > ==7218== by 0x4A40F52: __sflush (stdio/fflush.c:80)
>> > > ==7218== by 0x4A94726: __sfvwrite (stdio/fvwrite.c:191)
>> > > ==7218== by 0x4ACCA68: __sprint (stdio/vfprintf.c:111)
>> > > ==7218== by 0x4ACCA68: __vfprintf (stdio/vfprintf.c:1107)
>> > > ==7218== by 0x4AC8851: vfprintf (stdio/vfprintf.c:266)
>> > > ==7218== by 0x4A7C8A0: printf (stdio/printf.c:44)
>> > > ==7218== by 0x109AB8: main (x.c:14)
>> > >
>> > > Is there a way to avoid this? If so, it would be nice to mention that
>> > > in a pkg-readme.
>> > >
>> > > -Otto
>> >
>> > Do you want somethig like this?
>>
>> Thanks, that looks nice, but first I think it is good if I do an
>> investigation *why* this is reported.
>
> As far as I can see, the error is reported every time the value
> returned by TIB_GET() is used. In the case of write(2) that is via
> the ENTER_CANCEL_POINT and LEAVE_CANCEL_POINT macros.
Yes, this error seems to occur with the reference to the TIB retrieved
by TIB_GET().
>
> I have no clue how to fix this yet.
In order to suppress this error, we have to make TIB references not be
an error in Valgrind. We need more time.
By the way, uebayasi has been left developper team. Maybe your first
email did not reached uebayasi.
--
ASOU Masato
>
>
>>
>> -Otto
>>
>> >
>> > $ cvs -q diff .
>> > Index: devel/valgrind/pkg-readme
>> > ===================================================================
>> > RCS file: devel/valgrind/pkg-readme
>> > diff -N devel/valgrind/pkg-readme
>> > --- /dev/null 1 Jan 1970 00:00:00 -0000
>> > +++ devel/valgrind/pkg-readme 14 Dec 2020 05:18:59 -0000
>> > @@ -0,0 +1,23 @@
>> > +Suppressiong errors
>> > +
>> > +If you got a report on every syscall done as followes:
>> > +
>> > +==67551== Use of uninitialised value of size 8
>> > +==67551== at 0x4AC08F9: write (sys/w_write.c:26)
>> > +==67551== by 0x4A5AC12: __sflush (stdio/fflush.c:80)
>> > +==67551== by 0x4A4C676: __sfvwrite (stdio/fvwrite.c:191)
>> > +==67551== by 0x4A80CD8: __sprint (stdio/vfprintf.c:111)
>> > +==67551== by 0x4A80CD8: __vfprintf (stdio/vfprintf.c:1107)
>> > +==67551== by 0x4A7CAC1: vfprintf (stdio/vfprintf.c:266)
>> > +==67551== by 0x4A54680: printf (stdio/printf.c:44)
>> > +==67551== by 0x109BA5: main (main.c:19)
>> > +
>> > +You can use --gen-suppressions=yes and --suppressions=FILENAME
>> > options of
>> > +valgrind.
>> > +
>> > + $ yes | valgrind --gen-suppressions=yes ./a.out 2>supress.txt
>> > + $ sed -e '/^==.*[^{]$/d' -e 's/==.*{/{/' supress.log >
>> > supress.txt
>> > + $ valgrind --suppressions=supress.txt ./a.out
>> > +
>> > +See also:
>> > +https://www.valgrind.org/docs/manual/manual-core.html#manual-core.suppress
>> > --
>> > ASOU Masato
>>
