From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <balbi@kernel.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
Michal Nazarewicz <mina86@mina86.com>
Subject: Re: Virtual hub, resets etc...
Date: Sat, 06 Jul 2019 08:01:17 +1000 [thread overview]
Message-ID: <15f6a7e8cbe534cbc4f647f6f99cdef80a7b01ad.camel@kernel.crashing.org> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1907051005410.1606-100000@iolanthe.rowland.org>
On Fri, 2019-07-05 at 10:08 -0400, Alan Stern wrote:
> On Fri, 5 Jul 2019, Benjamin Herrenschmidt wrote:
>
> > > > > As for f_mass_storage, repeatedly attempting to queue an OUT transfer
> > > > > is normal behavior. The fact that one attempt gets an error doesn't
> > > > > stop the driver from making more attempts; the only thing that would
> > > > > stop it is being disabled by a config change, a suspend, a disconnect,
> > > > > or an unbind.
> > > >
> > > > Except it does that in a tight loop and locks up the machine...
> > >
> > > Well, that wouldn't happen if your UDC accepted the requests, right?
> >
> > Sure but it would be nice if the mass storage dealt with -ESHUTDOWN
> > properly and stopped :-) Or other errors... if the UDC HW for example
> > dies for some reason, mass storage will lockup.
>
> I suppose we could add code to check for this case and handle it,
> although I'm not sure what would be the right thing to do. Delay for
> one second and try again? Disable the gadget until the host does a
> reset?
I think just stop it until the next reset yes.
> > > Besides, f_mass_storage won't repeatedly try to queue an OUT transfer
> > > once it knows that it is suspended.
> >
> > Not afaik. But I might have missed something. I didn't see any suspend
> > callback in f_mass_storage.c...
>
> Oops, right. Sorry about that; my memory is slowly decaying. I need
> to upgrade my brain's RAM...
Haha, I wish I didn't have that problem too :)
Cheers,
Ben.
next prev parent reply other threads:[~2019-07-05 22:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 5:52 Virtual hub, resets etc Benjamin Herrenschmidt
2019-07-04 8:02 ` f_mass_storage configuration races (Was: Virtual hub, resets etc...) Benjamin Herrenschmidt
2019-07-04 8:04 ` [PATCH] usb: gadget: mass_storage: Fix races between fsg_disable and fsg_set_alt Benjamin Herrenschmidt
2019-07-04 16:13 ` Virtual hub, resets etc Alan Stern
2019-07-04 21:44 ` Benjamin Herrenschmidt
2019-07-04 21:58 ` Benjamin Herrenschmidt
2019-07-05 1:37 ` Alan Stern
2019-07-05 2:15 ` Benjamin Herrenschmidt
2019-07-05 14:20 ` Alan Stern
2019-07-05 22:06 ` Benjamin Herrenschmidt
2019-07-05 1:34 ` Alan Stern
2019-07-05 2:08 ` Benjamin Herrenschmidt
2019-07-05 14:08 ` Alan Stern
2019-07-05 22:01 ` Benjamin Herrenschmidt [this message]
2019-07-06 18:37 ` Alan Stern
2019-07-06 23:44 ` Benjamin Herrenschmidt
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