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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