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Date: Thu, 07 Feb 2002 19:12:21 -0800
From: Terry Lambert <tlambert2@mindspring.com>
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To: Julian Elischer <julian@elischer.org>
Cc: current@freebsd.org
Subject: Re: ucred for threads
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Julian Elischer wrote:
> yes.. well in booting yuo can have a null ucred. ( I know,s
> I've hit it), but in general you are correct.

[ ... ]

> > What is the default state of td->td_ucred?
> 
> on creation, NULL followed very rapidly with being set to
> p->p_ucred. (via crhold)

Non-problem, then.


> > If that's the case, then the code should be:
> >
> >         if (td->td_ucred != p->p_ucred) {
> >                 PROC_LOCK(p);
> >                 if (td->td_ucred) {
> >                         crfree(td->td_ucred);
> >                 }
> 
> without the if it crashes in boot sometimes.
> (this may not be true right now but was during my testing of
> the KSE kernel)

The place to fix this is by setting up a default reference to
a root/boot ucred, I think, for use by the initial process
template.

What are the consequences, if any, of me having removed the
setting the thing to NULL, during boot?  I guess that it
would leave the thread cred uninitialized.  Obviously, the
problem with your crash is in the crhold( NULL).  8-).

It seems to me that the test would leave threads with NULL
ucreds around as well, and just complicate things later.

Is there a reason you can't set up an initial ucred?

-- Terry

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