Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754111Ab0AELJ3 (ORCPT ); Tue, 5 Jan 2010 06:09:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752711Ab0AELJ3 (ORCPT ); Tue, 5 Jan 2010 06:09:29 -0500 Received: from www84.your-server.de ([213.133.104.84]:57447 "EHLO www84.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751741Ab0AELJ2 (ORCPT ); Tue, 5 Jan 2010 06:09:28 -0500 Subject: Re: USB: serial: kfifo_len locking From: Stefani Seibold To: Johan Hovold Cc: Pete Zaitcev , Greg KH , Andrew Morton , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org In-Reply-To: <20100105110418.GA10442@localhost> References: <20100104174352.GA26606@localhost> <1262632804.4814.17.camel@wall-e> <20100105004344.082bb69f@redhat.com> <20100105110418.GA10442@localhost> Content-Type: text/plain; charset="ISO-8859-15" Date: Tue, 05 Jan 2010 12:09:19 +0100 Message-ID: <1262689759.21020.2.camel@wall-e> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 7bit X-Authenticated-Sender: stefani@seibold.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2789 Lines: 65 Am Dienstag, den 05.01.2010, 12:04 +0100 schrieb Johan Hovold: > > This actually was a side effect of the "byte lost on close" patch > > that I submitted, it should be in Greg's tree. The relevant part goes > > like this: > > diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c > > index f1ea3a3..3372faa 100644 > > --- a/drivers/usb/serial/generic.c > > +++ b/drivers/usb/serial/generic.c > > @@ -386,12 +386,15 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty) > > > > dbg("%s - port %d", __func__, port->number); > > > > + spin_lock_irqsave(&port->lock, flags); > > if (serial->type->max_in_flight_urbs) { > > - spin_lock_irqsave(&port->lock, flags); > > chars = port->tx_bytes_flight; > > - spin_unlock_irqrestore(&port->lock, flags); > > - } else if (serial->num_bulk_out) > > - chars = kfifo_len(&port->write_fifo); > > + } else if (serial->num_bulk_out) { > > + /* This overcounts badly, but is good enough for drain wait. */ > > + chars = __kfifo_len(port->write_fifo); > > + chars += port->write_urb_busy * port->bulk_out_size; > > + } > > + spin_unlock_irqrestore(&port->lock, flags); > > > > dbg("%s - returns %d", __func__, chars); > > return chars; > > That is indeed what you submitted on Dec 7, but this is what is in > Greg's tree: > > http://git.kernel.org/?p=linux/kernel/git/gregkh/patches.git;a=blob;f=usb/usb-serial-mct_usb232-add-drain-on-close.patch;h=c464f1a82e93df0dd41762a8cb33b0b22e90cdd7;hb=1ea72e7c40b239c6b6f88a4993196be66fc3d892 > > 38 --- a/drivers/usb/serial/generic.c > 39 +++ b/drivers/usb/serial/generic.c > 40 @@ -369,8 +369,11 @@ int usb_serial_generic_write_room(struct > 41 room = port->bulk_out_size * > 42 (serial->type->max_in_flight_urbs - > 43 port->urbs_in_flight); > 44 - } else if (serial->num_bulk_out) > 45 + } else if (serial->num_bulk_out) { > 46 + /* This overcounts badly, but is good enough for drain wait. */ > 47 room = kfifo_avail(&port->write_fifo); > 48 + room += port->write_urb_busy * port->bulk_out_size; > 49 + } > 50 spin_unlock_irqrestore(&port->lock, flags); > 51 > 52 dbg("%s - returns %d", __func__, room); > > > Which does not make any sense at all. Bad merge? What do you say Greg? > I don't know where is your problem? This are two different functions usb_serial_generic_write_room() and usb_serial_generic_chars_in_buffer() Stefani -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/