From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
        pgsql-hackers@lists.postgresql.org
Subject: Re: valgrind issues on Fedora 28
In-reply-to: <9063c043-83cd-b439-a928-622a743edd2c@2ndquadrant.com>
References: <20181106173527.omm63tiaguxft7mg@alvherre.pgsql>
 <f6577fe9-def2-7614-958f-9a8fb810f666@2ndquadrant.com>
 <23c8e539-6777-1793-0939-12e73cb98314@2ndquadrant.com>
 <9063c043-83cd-b439-a928-622a743edd2c@2ndquadrant.com>
Comments: In-reply-to Tomas Vondra <tomas.vondra@2ndquadrant.com>
	message dated "Sun, 18 Nov 2018 00:11:54 +0100"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <16352.1544760625.1@sss.pgh.pa.us>
Content-Transfer-Encoding: quoted-printable
Date: Thu, 13 Dec 2018 23:10:25 -0500
Message-ID: <16353.1544760625@sss.pgh.pa.us>
Precedence: bulk

Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
> On 11/8/18 1:07 PM, Tomas Vondra wrote:
>> Not sure what to do about this - maybe we should wildcard this first
>> frame, to accept all wcsnlen variants. Opinions?

> I've committed this with the first frame wirldcarded, and backpatched it
> all the way back to 9.4.

So I just got around to trying to do some valgrind testing for the first
time in a couple of months, and what I find is that this patch completely
breaks valgrind for me: it exits immediately with complaints like

=3D=3D00:00:00:00.222 14821=3D=3D FATAL: in suppressions file "/home/postg=
res/pgsql/src/tools/valgrind.supp" near line 227:
=3D=3D00:00:00:00.222 14821=3D=3D    unknown tool suppression type
=3D=3D00:00:00:00.222 14821=3D=3D exiting now.

After a bit of hair-pulling I found that the line number report is
a lie, and what it's really unhappy about is the "Memcheck:Addr32"
specification on line 236.  This is not terribly surprising perhaps
considering that "Addr32" isn't even documented on what should be
the authoritative page:
http://valgrind.org/docs/manual/mc-manual.html#mc-manual.suppfiles

This is valgrind 3.8.1 (RHEL6's version), so not bleeding edge exactly,
but we have very little evidence about how far back the committed patch
works.  I'm inclined to think we can't use this solution.

			regards, tom lane