usb/80685: panic in usb_cold_explore() at begining

[Richard S. Conto]

The following reply was made to PR usb/80685; it has been noted by GNATS.

From: "Richard S. Conto" <rsc at merit.edu>
To: jwm at CSUA.Berkeley.EDU
Cc: bug-followup at FreeBSD.org, rsc at merit.edu, rsc at merit.edu
Subject: Re: usb/80685: panic in usb_cold_explore() at begining 
Date: Mon, 16 May 2005 10:44:17 -0400

 I did a little exploring of this shortly after I opened this
 trouble report. I modified the KASSERT() to print the value of
 "cold", and it was "0" for me.  That didn't seem very helpful,
 and more trouble shooting was needed.  However, as I thought it
 was a timing related bug at the time, I didn't try to make time
 to trace the problem further.  A brief inspection of the code
 suggests a possible path whereby "usb_coldexplist" is empty when
 "usb_cold_explore()" is run, but I haven't tried to debug that.
 This machine is so old, cranky, and (temporarily) critical to me
 that I just haven't had the energy to follow this through.
 
 I'm tempted to throw some cheapo USB device on the interface card
 so I don't have to open the case and remove the card.
 
 > originally from: John Milford <jwm at CSUA.Berkeley.EDU>
 > originally to:   bug-followup at FreeBSD.org
 > originally cc: rsc at merit.edu
 > subject: Re: usb/80685: panic in usb_cold_explore() at begining
 > date: Sat, 14 May 2005 12:22:38 -0700
 > ref: <200505141922.j4EJMcLH044086 at soda.csua.berkeley.edu>
 > --------
 >
 >I have hit this too with 4.11-STABLE I cvsup'ed last night.  My system
 >is a Dual Athlon.  If there is something I can do to help with this
 >I'll take a shot at it.
 >
 >I say Julian had recommended some prints for debugging, and I added
 >those, but without a serial console it is tough for me to see if they
 >are getting printed early on.  However the only print I can see is
 >right before the panic, "HEY WE GOT HERE!".
 >
 >printf("HEY WE GOT HERE!\n");
 >        KASSERT(cold || TAILQ_EMPTY(&usb_coldexplist),
 >            ("usb_cold_explore: busses to explore when !cold"));
 >        while (!TAILQ_EMPTY(&usb_coldexplist)) {
 >                sc = TAILQ_FIRST(&usb_coldexplist);
 >                TAILQ_REMOVE(&usb_coldexplist, sc, sc_coldexplist);
 >printf("probing a USB 1.1 bus.\n");
 >
 >
 >With my old kernel (4.11-STABLE from end of Dec.)
 >
 >ohci0: <OHCI (generic) USB controller> mem 0xf1000000-0xf1000fff irq
 >10 at device 0.0 on pci2
 >usb0: OHCI version 1.0, legacy support
 >usb0: <OHCI (generic) USB controller> on ohci0
 >usb0: USB revision 1.0
 >uhub0: AMD OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
 >uhub0: 4 ports with 4 removable, self powered
 >ums0: Logitech USB Receiver, rev 1.10/16.00, addr 2, iclass 3/1
 >ums0: 7 buttons and Z dir.
 >
 >!DSPAM:4286500828253684526439!
 
 -- 
     Richard Conto
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