From: Johan Hovold <jhovold@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oliver Neukum <oliver@neukum.org>,
Matthew Garrett <mjg59@srcf.ucam.org>,
dvomlehn@cisco.com, gregkh@suse.de, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [REGRESSION] "USB: use kfifo to buffer usb-generic serial writes" causes gobi_loader to hang
Date: Tue, 19 Jan 2010 16:25:36 +0100 [thread overview]
Message-ID: <20100119152536.GA2104@localhost> (raw)
In-Reply-To: <20100119142657.02856d15@lxorguk.ukuu.org.uk>
> > The log shows no call to usb_serial_generic_write_room()
> > Do you consider this a bug in the tty layer?
>
> Actually this all makes sense because of where it was hanging. A reply of
> 0 to the tty->ops->write will cause it to either return (O_NONBLOCK) or
> sleep in the n_tty write code waiting for a write_wait wakeup
> (tty_wakeup(tty))
>
> So the fix does indeed look correct.
Is it really a fix? If the fifo is already full the write urb should be
in use and Oliver's patch would amount to only a minor optimisation as
usb_serial_generic_write_start would return 0 anyway.
/Johan
next prev parent reply other threads:[~2010-01-19 15:25 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-17 2:55 [REGRESSION] "USB: use kfifo to buffer usb-generic serial writes" causes gobi_loader to hang Matthew Garrett
2010-01-17 8:13 ` Marcel Holtmann
2010-01-17 9:14 ` Oliver Neukum
2010-01-18 1:58 ` Matthew Garrett
2010-01-18 17:25 ` Oliver Neukum
2010-01-18 20:14 ` Matthew Garrett
2010-01-19 13:20 ` Oliver Neukum
2010-01-19 13:29 ` Alan Cox
2010-01-19 13:57 ` Oliver Neukum
2010-01-19 14:21 ` Alan Cox
2010-01-19 15:15 ` Oliver Neukum
2010-01-19 14:26 ` Alan Cox
2010-01-19 15:25 ` Johan Hovold [this message]
2010-01-19 15:52 ` Johan Hovold
2010-01-19 16:27 ` Alan Cox
2010-01-19 18:44 ` Oliver Neukum
2010-01-19 19:45 ` Johan Hovold
2010-01-28 17:45 ` Greg KH
2010-01-28 18:40 ` Oliver Neukum
2010-01-28 22:32 ` Greg KH
2010-02-03 16:46 ` Matthew Garrett
2010-02-03 17:21 ` Oliver Neukum
2010-02-03 22:37 ` Matthew Garrett
2010-02-03 22:58 ` Oliver Neukum
2010-02-05 19:58 ` Matthew Garrett
2010-02-05 21:35 ` Matthew Garrett
2010-02-08 19:00 ` Oliver Neukum
2010-02-05 21:59 ` Oliver Neukum
2010-02-13 2:09 ` Anssi Hannula
2010-02-13 2:50 ` Alan Stern
2010-02-13 7:11 ` Oliver Neukum
2010-02-13 13:35 ` Anssi Hannula
2010-02-13 19:01 ` Anssi Hannula
2010-02-15 13:08 ` Oliver Neukum
2010-02-20 16:03 ` Anssi Hannula
2010-02-20 18:19 ` Oliver Neukum
2010-02-21 21:28 ` Alan Stern
2010-02-21 21:42 ` Anssi Hannula
2010-02-21 22:12 ` Oliver Neukum
2010-02-21 23:06 ` Anssi Hannula
2010-02-21 23:13 ` Anssi Hannula
2010-02-21 23:21 ` Anssi Hannula
2010-02-22 15:28 ` Alan Stern
2010-02-22 18:35 ` Anssi Hannula
2010-02-22 19:10 ` Alan Stern
2010-02-22 19:14 ` Matthew Garrett
2010-02-22 20:12 ` Alan Stern
2010-02-24 2:33 ` Anssi Hannula
2010-02-22 19:24 ` Anssi Hannula
2010-02-22 20:10 ` Alan Stern
2010-02-22 21:24 ` Alan Cox
2010-02-22 21:23 ` Matthew Garrett
2010-02-22 23:26 ` Oliver Neukum
2010-02-23 1:55 ` Anssi Hannula
2010-02-21 22:09 ` Oliver Neukum
2010-02-21 21:37 ` Anssi Hannula
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