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Date:      Mon, 11 Sep 2000 13:07:52 -0700 (PDT)
From:      John Baldwin <jhb@pike.osd.bsdi.com>
To:        freebsd-alpha@FreeBSD.org
Subject:   Re: cvs commit: src/sys/pci pcisupport.c
Message-ID:  <200009112007.NAA60493@pike.osd.bsdi.com>

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Doug Rabson wrote:
> That particular panic is the one I saw before removing the calls to
> mtx_enter/mtx_exit from interrupt().

I've debugged it some more and it looks like a bug somewhere in the mutex
code.  We are releasing the Giant lock when it is uncontested, but
mtx_exit() is still calling mtx_exit_hard(), which it should only be
calling for contested locks.  As a result, when we try to pull a process
off the blocked list so we can give it the mutex and schedule it to run,
we dereference a NULL pointer.

-- 

John Baldwin <jhb@bsdi.com> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.cslab.vt.edu/~jobaldwi/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/


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