Date: Thu, 11 Sep 2008 20:44:42 +0200 From: Hans Petter Selasky <hselasky@c2i.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: volker@vwsoft.com, rink@freebsd.org, current@freebsd.org, freebsd-usb@freebsd.org, fbsd-current@mawer.org Subject: Re: "legacy" usb stack fixes Message-ID: <200809112044.43749.hselasky@c2i.net> In-Reply-To: <20080911.082418.775964060.imp@bsdimp.com> References: <48B3299F.5080101@vwsoft.com> <20080911103343.GH1413@rink.nu> <20080911.082418.775964060.imp@bsdimp.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi,
Would anyone object if I make one non-Giant locked CAM bus for all USB2
devices? Something like:
static void
umass_create_cam_bus_sysinit()
{
devq = cam_simq_alloc(1 /* maximum openings */ );
if (devq == NULL) {
return (ENOMEM);
}
umass_global_sim = cam_sim_alloc
(&umass_cam_action, &umass_cam_poll,
DEVNAME_SIM,
NULL /* priv */ ,
0 /* unit number */ ,
#if (__FreeBSD_version >= 700037)
&umass_global_mtx /* mutex */ ,
#endif
1 /* maximum device openings */ ,
0 /* maximum tagged device openings */ ,
devq);
return;
}
static void
umass_destroy_cam_bus_sysuninit()
{
....
}
SYSINIT(&umass_create_cam_bus_sysinit);
SYSUNINIT(&umass_destroy_cam_bus_sysuninit);
--HPS
On Thursday 11 September 2008, M. Warner Losh wrote:
> In message: <20080911103343.GH1413@rink.nu>
>
> Rink Springer <rink@freebsd.org> writes:
> : On Thu, Sep 11, 2008 at 10:13:22AM +0200, Hans Petter Selasky wrote:
> : > I also see crashes with my new stuff and the umass driver when the USB
> : > device is un-plugged too early. The backtraces I've got so far does not
> : > indicate a USB problem, though ....
> :
> : That is correct, this is a bug in CAM. More specifically, CAM does not
> : handle the removal of busses well. There are two possible options:
> :
> : 1) Obviously, fix CAM to handle this scenarion
> : DragonflyBSD seems to have a lot of fixes in this area, which I
> : intend to take a look at 'some day' (no thanks to $reallife...)
>
> This is the better option.
>
> : 2) Create a CAM bus per USB bus
> : I think this is reasonable, and it makes a lot more sense than the
> : one-bus-per-device approach that we have now. The idea is that
> : every USB controller hub creates a CAM bus, and umass(4) attaches to
> : this bus instead of creating its own. Of course, until CAM is fixed,
> : detaching PCMCIA or equivalent USB cards will still cause panics, but
> : it would be a lot better than it is now...
>
> This would mitigate the problem, but there's a lot of people that use
> CardBus USB cards, and they complain to me from time to time of the
> problem.
>
> Fortunately, the wireless broadband cards that are a usb host
> controller plus usb device in CardBus format aren't affected...
>
> : Personally, I'd like to see option 2 implemented in the USB2 stack, as
> : it avoids the issue and makes a lot more sense from user perspective
> : (I'm probably onot the only one who gets scared by 'camcontrol devlist'
> : if you have a single MP3 player which advertises 2 disks :-))
>
> It may make good sense for other reasons as well. Firewire does
> something similar, and also umass used to do exactly this. There's
> also problems right now with huge bus load leading to devices
> disconnecting and reconnecting for some suck-ass, but common,
> chipsets. If things were implemented this way, then there'd be
> options to silently reconnect the device when it goes away and comes
> back a few hundred milliseconds later... Firewire handles this case
> too, at the expense of never disconnecting the disk, which isn't so
> good for a thumb drive...
>
> Warner
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200809112044.43749.hselasky>