From: Ladislav Michl <ladis@linux-mips.org>
To: Johan Hovold <johan@kernel.org>
Cc: linux-usb@vger.kernel.org
Subject: USB: serial: ti_usb_3410_5052: Avoid goto in bulk in callback
Date: Wed, 13 Dec 2017 12:32:47 +0100 [thread overview]
Message-ID: <20171213113247.GA20556@lenoch> (raw)
On Wed, Dec 13, 2017 at 12:16:05PM +0100, Johan Hovold wrote:
> On Mon, Dec 11, 2017 at 01:44:57PM +0100, Ladislav Michl wrote:
> > On Mon, Dec 11, 2017 at 12:52:46PM +0100, Johan Hovold wrote:
> > > On Mon, Dec 11, 2017 at 12:32:49PM +0100, Ladislav Michl wrote:
> > > > On Mon, Dec 11, 2017 at 11:10:35AM +0100, Johan Hovold wrote:
> > [snip]
> > > > > I'm afraid I don't consider this an improvement. I prefer using gotos
> > > > > for error paths, while keeping the success path out of the status
> > > > > switch.
> > > > >
> > > > > Furthermore, this isn't functionally equivalent as we'd not longer log
> > > > > an error for -EPIPE.
> > > >
> > > > Yes, you are right... Now, shouldn't we react somehow to stalled endpoint?
> > > > Tty side seems to be unaware of it.
> > >
> > > Recovering from a stalled endpoint is a bit involved, so for now we
> > > typically just log an error an bail out (forcing the user to reopen the
> > > port). This seems to work well enough as this condition should be rare.
> >
> > I just do not see this in code. I would expect pending tty I/O operation
> > would fail once USB device errors out with -EPIPE, so tty side consumer gets
> > notified about error. Either it is not there or I did not look hard enough :)
>
> No, we do not provide any error notification besides logging an error
> when an endpoint has been stalled (i.e. in case of a read, you would not
> receive any more data before the halt condition has been cleared).
Hmm, could we make 1aba579f3cf5 a bit more generic then?
> Given that there's been no reports about this being an issue (for the
> past ten years and that I can recall), this crude handling appears to
> suffice.
Because embedded people tend to power cycle stuck device on timeout.
That involves project specific hacks in userspace, which could be
probably handled better.
Best regards,
ladis
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next reply other threads:[~2017-12-13 11:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-13 11:32 Ladislav Michl [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-12-13 11:50 USB: serial: ti_usb_3410_5052: Avoid goto in bulk in callback Johan Hovold
2017-12-13 11:16 Johan Hovold
2017-12-11 12:44 Ladislav Michl
2017-12-11 11:52 Johan Hovold
2017-12-11 11:32 Ladislav Michl
2017-12-11 10:10 Johan Hovold
2017-12-10 23:09 Ladislav Michl
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