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Date:      Sun, 21 Aug 2022 11:25:43 +0200
From:      Michael Tuexen <michael.tuexen@macmic.franken.de>
To:        Gleb Smirnoff <glebius@FreeBSD.org>
Cc:        "src-committers@freebsd.org" <src-committers@freebsd.org>, "dev-commits-src-all@freebsd.org" <dev-commits-src-all@freebsd.org>, "dev-commits-src-main@freebsd.org" <dev-commits-src-main@freebsd.org>
Subject:   Re: git: 8338690a0a43 - main - ip_reass: provide sysctl MIB returning IP fragment TTL
Message-ID:  <9EFEAD3E-F940-43C3-9465-FA26DCBD1888@macmic.franken.de>
In-Reply-To: <YwGWEA4zMws2lhol@FreeBSD.org>
References:  <202208202041.27KKfe9e061428@gitrepo.freebsd.org> <D30BFB00-3937-4982-8364-BF584084D5BE@macmic.franken.de> <YwGWEA4zMws2lhol@FreeBSD.org>

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> On 21. Aug 2022, at 04:18, Gleb Smirnoff <glebius@FreeBSD.org> wrote:
>=20
> On Sun, Aug 21, 2022 at 12:07:39AM +0200, Michael Tuexen wrote:
> M> > commit 8338690a0a43c8b11a382e2160f8eedb9aeecf91
> M> > Author:     Gleb Smirnoff <glebius@FreeBSD.org>
> M> > AuthorDate: 2022-08-20 20:33:39 +0000
> M> > Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
> M> > CommitDate: 2022-08-20 20:39:12 +0000
> M> >=20
> M> >    ip_reass: provide sysctl MIB returning IP fragment TTL
> M> >=20
> M> >    For now it is read-only, but eventually the cycle that goes =
over
> M> >    all fragments should be refactored and this MIB should also =
become
> M> >    read/write.
> M> >=20
> M> >    This MIB will allow SNMP daemons to implement MIB-II =
ipReasmTimeout MIB
> M> >    straightfoward.  Right now net-snmp compilation is broken by =
1922eb3e9c2.
> M> >    The base system bsnmpd is not broken just because it ignored =
PR_SLOWTIMO,
> M> >    and thus always returned incorrectly doubled value for =
ipReasmTimeout.
> M> > ---
> M> > sys/netinet/ip_reass.c | 4 ++++
> M> > 1 file changed, 4 insertions(+)
> M> >=20
> M> > diff --git a/sys/netinet/ip_reass.c b/sys/netinet/ip_reass.c
> M> > index 0420091e0a2a..e581e2e622c7 100644
> M> > --- a/sys/netinet/ip_reass.c
> M> > +++ b/sys/netinet/ip_reass.c
> M> > @@ -167,6 +167,10 @@ SYSCTL_PROC(_net_inet_ip, OID_AUTO, =
maxfragbucketsize,
> M> >     sysctl_maxfragbucketsize, "I",
> M> >     "Maximum number of IPv4 fragment reassembly queue entries per =
bucket");
> M> >=20
> M> > +static u_int ipfragttl =3D IPFRAGTTL / 2;
> M> > +SYSCTL_UINT(_net_inet_ip, OID_AUTO, fragttl, CTLFLAG_RD, =
&ipfragttl,
> M> > +    IPFRAGTTL / 2, "IP fragment life time on reassembly queue");
> M> What unit is used? seconds? milliseconds? You might want to state =
that.
> M> What us the semantic of IPFRAGTTL? What is the unit of that =
constant?
>=20
> I'll add '(seconds)' to the sysctl description.
Perfect, thank you.
>=20
> The semantic of IPFRAGTTL is ugly. It is number of timeouts, which are =
0.5
> second. A legacy of PR_SLOWTIMO. This will go away, so is not worth =
documenting.
Not sure what goes away. IPFRAGTTL or PR_SLOWTIMO. If IPFRAGTTL goes =
away, everything
is fine. If not, you might change the unit of IPFRAGTTL to seconds an =
update the
code correspondingly.

Best regards
Michael
>=20
> --=20
> Gleb Smirnoff




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