USB to RS232 converter problem (prolific chip)

Kostik Belousov kostikbel at gmail.com
Sat Apr 5 23:14:19 UTC 2008


On Sat, Apr 05, 2008 at 04:10:10PM -0600, M. Warner Losh wrote:
> In message: <20080405215838.GA27195 at eos.sc1.parodius.com>
>             Jeremy Chadwick <koitsu at freebsd.org> writes:
> : Bottom line: the current FreeBSD USB stack is very fragile and
> : unreliable.  You may want to try the usb4bsd kernel patches (I think
> : that's what it's called), some have had better luck with those.  Search
> : the web.
> 
> This crash has nothing to do with the usb stack.  The root cause is
> the device deletion code nulls out a pointer.  There's a routine that
> is sleeping which is woken up and the null pointer gets dereferenced
> leading to the crash.
I believe that I fixed this in the HEAD and RELENG_7.

MFC to the RELENG_6 is possible, but I have no facilities to test.

> 
> The current usb stack isn't as fragile as it was in the 5.x days.
> While there are problems, this one isn't due to that.  The same thing
> happens when you eject a PC Card 16550 COM device, due to the same
> bug.
> 
> Warner
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