Date: Wed, 24 Oct 2001 11:59:52 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Jonathan Lemon <jlemon@flugsvamp.com> Cc: Jun Kuriyama <kuriyama@imgsrc.co.jp>, David Wolfskill <david@catwhisker.org>, Jonathan Lemon <jlemon@flugsvamp.com>, Current <FreeBSD-current@FreeBSD.ORG> Subject: Re: panic: vrele: missed vn_close Message-ID: <200110241859.f9OIxqs97073@apollo.backplane.com> References: <200110230121.f9N1LTa24181@freefall.freebsd.org> <7mg089l1bn.wl@waterblue.imgsrc.co.jp> <200110241838.f9OIcCR96868@apollo.backplane.com> <20011024135503.C75389@prism.flugsvamp.com>
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:
:Hmm. The way the revamped console code works is this:
:
: cn_devopen() calls vn_open() to open the device. If this is not a
:VCHR device, then it is closed. Otherwise, the vnode is stashed in
:cnd->cnd_vp.
:
: When the device is closed though cnclose(), it walks through a list
:of console devices, and if cnd_vp != NULL, calls vn_close() for that
:vnode, and then NULLs out cnd_vp. (drops the reference.)
:
: My understanding is that vn_open/vn_close will track the count of
:outstanding references to the vnode, so this should be safe to do.
:--
:Jonathan
The panic is due to v_writecount not being properly adjusted. If a
vnode is opened with FWRITE in vn_open(), then it must be closed with
VWRITE in vn_close() or v_writecount will not be properly adjusted and cause
the panic in question to occur later in vrele().
I suspect that this is the problem with the devfs/console code.
-Matt
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