Subject: Re: purpose of mbuf type MT_HEADER (see pr kern/24713)
To: None <>
From: Pavel Cahyna <>
List: tech-net
Date: 10/05/2004 11:33:15
On Tue, 05 Oct 2004 00:06:07 +0000, YAMAMOTO Takashi wrote:

>> I propose to remove the test for the time being, (one line code change
>> plus one line comment change) and pull up to the release branch.
> no strong objection from me.  but see below.
>> The case caught which panics in 26973 (MT_DATA vs. MT_PKTHDR) is only
>> very vaguely described in the mbuf documentation, be it online or in the
>> literature, and it doesn't surprise me that more cases of this type
>> difference are found; half of the test (introduced in 1.72 of uipc_mbuf.c
>> I think) was already removed on the 1.78 to remove a similar panic for
> you can find the following comment in uipc_mbuf.c since rev.1.1.
> 	Both chains must be of the same type (e.g. MT_DATA).

If the difference between MT_DATA and MT_PKTHDR is vaguely defined,
why not keep the test and get rid of MT_PKTHDR completely and replace
it with MT_DATA?

Thanks for your interest.

Bye	Pavel