Date: Sat, 06 Oct 2007 23:53:58 -0700 (PDT)
Message-Id: <20071006.235358.104048815.davem@davemloft.net>
To: dbrownell@users.sourceforge.net
CC: linux-usb-users@lists.sourceforge.net, linux-kernel@vger.kernel.org,
       greg@kroah.com
Subject: OHCI root_port_reset() deadly loop...
From: David Miller <davem@davemloft.net>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1001
Lines: 24


When root_port_reset() in ohci-hub.c polls for the end of the reset,
it puts no limit on the loop and will only exit the loop when either
the RH_PS_PRS bit clears or the register returns all 1's (the latter
condition is a recent addition).

If for some reason the bit never clears, we sit here forever and never
exit the loop.

I actually hit this on one of my machines, and I'm trying to track
down what's happening.

Regardless of why my machine is doing this, there absolutely should be
some upper bound put on the number of times we will run through this
loop, perhaps enough such that up to 5 seconds elapses waiting for the
reset bit to clear.  And if it times out we should print a loud
message onto the console, but still try to continue.

Thanks!
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/