From: Alan Stern <stern@rowland.harvard.edu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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: Fri, 5 Jul 2019 10:08:47 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1907051005410.1606-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <03595b660f319d5fb958ccbacbfe51002bff2314.camel@kernel.crashing.org>
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?
> > 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...
Alan Stern
next prev parent reply other threads:[~2019-07-05 14:08 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 [this message]
2019-07-05 22:01 ` Benjamin Herrenschmidt
2019-07-06 18:37 ` Alan Stern
2019-07-06 23:44 ` Benjamin Herrenschmidt
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