usb/113964: [patch] ucom(4): kernel panic when dropping a connection

[M. Warner Losh]

The following reply was made to PR usb/113964; it has been noted by GNATS.

From: "M. Warner Losh" <imp at bsdimp.com>
To: kazuaki at aliceblue.jp
Cc: FreeBSD-gnats-submit at FreeBSD.ORG
Subject: Re: usb/113964: [patch] ucom(4): kernel panic when dropping a
 connection
Date: Sat, 23 Jun 2007 12:25:20 -0600 (MDT)

 In message: <200706231136.l5NBa61H001748 at eyes.aliceblue.jp>
             Kazuaki ODA <kazuaki at 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