Date: Sun, 24 Jun 2007 06:20:08 GMT From: "M. Warner Losh" <imp@bsdimp.com> To: freebsd-usb@FreeBSD.org Subject: Re: usb/113964: [patch] ucom(4): kernel panic when dropping a connection Message-ID: <200706240620.l5O6K7r1038031@freefall.freebsd.org>
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The following reply was made to PR usb/113964; it has been noted by GNATS.
From: "M. Warner Losh" <imp@bsdimp.com>
To: kazuaki@aliceblue.jp
Cc: FreeBSD-gnats-submit@FreeBSD.ORG
Subject: Re: usb/113964: [patch] ucom(4): kernel panic when dropping a
connection
Date: Sun, 24 Jun 2007 00:14:21 -0600 (MDT)
In message: <467D7AE6.2090302@aliceblue.jp>
Kazuaki ODA <kazuaki@aliceblue.jp> writes:
: M. Warner Losh wrote:
: > In message: <200706231136.l5NBa61H001748@eyes.aliceblue.jp>
: > Kazuaki ODA <kazuaki@aliceblue.jp> writes:
: > : I don't know the proper fix but the following patch is workaround for
: > : me.
: > :
: > : --- ucom.c.patch begins here ---
: > : --- sys/dev/usb/ucom.c.orig 2007-06-22 23:45:37.000000000 +0900
: > : +++ sys/dev/usb/ucom.c 2007-06-23 17:47:18.000000000 +0900
: > : @@ -532,6 +532,9 @@
: > : if (sc->sc_dying)
: > : return;
: > :
: > : + if (sc->sc_oxfer == NULL)
: > : + return;
: > : +
: > : s = spltty();
: > :
: > : if (tp->t_state & TS_TBLOCK) {
: > : --- ucom.c.patch ends here ---
: >
: > This is a good workaround. However, why does the tty->t_oproc get
: > called after the tty->t_close routine which sets sc->sc_oxfer to NULL?
: >
: > Warner
:
: Unfortunately, I have no idea. But it seems the changes of tty
: subsystem and ucom.c rev. 1.56 are related to the issue.
:
: * On 5.x-RELEASE, where ucom.c rev. 1.56 has been MFCed, we get no panic.
:
: * On 6.x-RELEASE or 7.0-CURRENT, we get a panic.
:
: * After backing out ucom.c rev. 1.56, no panic on 6.x-RELEASE or
: 7.0-CURRENT.
OK. This is an important hint. However, it will take a while to
study it.
Warner
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