From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Brownell <david-b@pacbell.net>
Cc: davem@davemloft.net, linux-usb-users@lists.sourceforge.net,
linux-kernel@vger.kernel.org, greg@kroah.com
Subject: Re: OHCI root_port_reset() deadly loop...
Date: Tue, 09 Oct 2007 15:13:36 +1000 [thread overview]
Message-ID: <1191906816.6355.62.camel@pasglop> (raw)
In-Reply-To: <20071009040917.DC7FC237446@adsl-69-226-248-13.dsl.pltn13.pacbell.net>
> Yes, that's why I asked about EHCI. My speculation would be that
> OHCI starts the reset, and EHCI claims the port before it completes;
> or contrariwise OHCI starts the reset right after EHCI claims it.
>
> And there's some point in that process where a hardware race makes
> the trouble you've observed. I believe there are plenty of other
> places where it's perfectly fine if EHCI grabs the port, or this
> little race would have shown up many times before.
Since we can't know which O/UHCI is paired with which EHCI, we can't
really have generic code to deal with that race, but maybe we can be
smart and basically mutex khubd activity such as port reset vs.
registration of any new HCD ?
I'm not even sure module load order is 100% fault proof here since khubd
spawns as a thread...
Ben.
next prev parent reply other threads:[~2007-10-09 5:13 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-07 6:53 OHCI root_port_reset() deadly loop David Miller
2007-10-07 7:31 ` David Brownell
2007-10-07 7:51 ` David Miller
2007-10-08 23:54 ` David Miller
2007-10-09 3:10 ` Greg KH
2007-10-09 3:16 ` David Miller
2007-10-09 3:34 ` David Brownell
2007-10-09 3:42 ` David Miller
2007-10-09 4:39 ` Greg KH
2007-10-09 4:47 ` David Miller
2007-10-09 5:11 ` Benjamin Herrenschmidt
2007-10-09 6:06 ` Greg KH
2007-10-09 19:22 ` [linux-usb-devel] " David Brownell
2007-10-10 15:32 ` Alan Stern
2007-10-09 5:00 ` David Brownell
2007-10-09 5:23 ` David Miller
2007-10-09 6:43 ` Benjamin Herrenschmidt
2007-10-09 18:48 ` David Brownell
2007-10-09 16:01 ` [Linux-usb-users] " Alan Stern
2007-10-09 17:39 ` Greg KH
2007-10-09 18:42 ` Alan Stern
2007-10-09 18:59 ` David Brownell
2007-10-09 21:27 ` David Miller
2007-10-09 21:43 ` David Brownell
2007-10-09 22:00 ` David Miller
2007-10-10 4:35 ` David Miller
2007-10-15 22:01 ` David Miller
2007-10-15 23:39 ` David Brownell
2007-10-15 23:58 ` David Miller
2007-10-16 15:23 ` Alan Stern
2007-10-16 22:06 ` David Miller
2007-10-16 22:20 ` Greg KH
2007-10-17 15:56 ` Alan Stern
2007-10-16 22:08 ` David Miller
2007-10-17 15:51 ` Alan Stern
2007-10-17 23:03 ` David Miller
2007-10-18 14:28 ` Alan Stern
2007-10-16 18:26 ` David Brownell
2007-10-09 4:09 ` David Brownell
2007-10-09 5:13 ` Benjamin Herrenschmidt [this message]
2007-10-09 5:26 ` David Miller
2007-10-09 6:37 ` Benjamin Herrenschmidt
2007-10-09 4:36 ` David Brownell
2007-10-09 4:44 ` David Miller
2007-10-09 16:38 ` David Brownell
2007-10-09 20:41 ` David Miller
2007-10-09 20:46 ` Greg KH
2007-10-09 21:05 ` David Brownell
2007-10-09 21:09 ` David Brownell
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