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Message-ID: <1262690734.22009.3.camel@wall-e>
Date: Tue, 05 Jan 2010 12:25:34 +0100
From: Stefani Seibold <stefani@...bold.net>
To: Johan Hovold <jhovold@...il.com>
Cc: Pete Zaitcev <zaitcev@...hat.com>, Greg KH <greg@...ah.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: USB: serial: kfifo_len locking
Am Dienstag, den 05.01.2010, 12:14 +0100 schrieb Johan Hovold:
> > >
> > > 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()
>
> Exactly my point.
>
> The drain patch needed to modify chars_in_buffer, but the patch in Greg's
> tree modifies write_room instead (which does not make sense and was
> neither part of the submitted patch).
>
Sorry, but i am not sure if i the right address about your complains.
The only thing i have done in the usb serial driver is the port to the
new kfifo API. This is the original patch i had posted:
diff -u -N -r -p old/drivers/usb/serial/generic.c new/drivers/usb/serial/generic.c
--- old/drivers/usb/serial/generic.c 2009-12-23 08:54:06.966476248 +0100
+++ new/drivers/usb/serial/generic.c 2009-12-23 09:06:25.778474708 +0100
@@ -276,7 +276,7 @@ static int usb_serial_generic_write_star
if (port->write_urb_busy)
start_io = false;
else {
- start_io = (kfifo_len(port->write_fifo) != 0);
+ start_io = (kfifo_len(&port->write_fifo) != 0);
port->write_urb_busy = start_io;
}
spin_unlock_irqrestore(&port->lock, flags);
@@ -285,7 +285,7 @@ static int usb_serial_generic_write_star
return 0;
data = port->write_urb->transfer_buffer;
- count = kfifo_out_locked(port->write_fifo, data, port->bulk_out_size, &port->lock);
+ count = kfifo_out_locked(&port->write_fifo, data, port->bulk_out_size, &port->lock);
usb_serial_debug_data(debug, &port->dev, __func__, count, data);
/* set up our urb */
@@ -345,7 +345,7 @@ int usb_serial_generic_write(struct tty_
return usb_serial_multi_urb_write(tty, port,
buf, count);
- count = kfifo_in_locked(port->write_fifo, buf, count, &port->lock);
+ count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
result = usb_serial_generic_write_start(port);
if (result >= 0)
@@ -370,7 +370,7 @@ int usb_serial_generic_write_room(struct
(serial->type->max_in_flight_urbs -
port->urbs_in_flight);
} else if (serial->num_bulk_out)
- room = port->write_fifo->size - kfifo_len(port->write_fifo);
+ room = kfifo_avail(&port->write_fifo);
spin_unlock_irqrestore(&port->lock, flags);
dbg("%s - returns %d", __func__, room);
@@ -391,7 +391,7 @@ int usb_serial_generic_chars_in_buffer(s
chars = port->tx_bytes_flight;
spin_unlock_irqrestore(&port->lock, flags);
} else if (serial->num_bulk_out)
- chars = kfifo_len(port->write_fifo);
+ chars = kfifo_len(&port->write_fifo);
dbg("%s - returns %d", __func__, chars);
return chars;
@@ -507,7 +507,7 @@ void usb_serial_generic_write_bulk_callb
if (status) {
dbg("%s - nonzero multi-urb write bulk status "
"received: %d", __func__, status);
- kfifo_reset(port->write_fifo);
+ kfifo_reset_out(&port->write_fifo);
} else
usb_serial_generic_write_start(port);
}
diff -u -N -r -p old/drivers/usb/serial/usb-serial.c new/drivers/usb/serial/usb-serial.c
--- old/drivers/usb/serial/usb-serial.c 2009-12-23 08:54:23.204476351 +0100
+++ new/drivers/usb/serial/usb-serial.c 2009-12-23 09:06:39.664475312 +0100
@@ -595,8 +595,7 @@ static void port_release(struct device *
usb_free_urb(port->write_urb);
usb_free_urb(port->interrupt_in_urb);
usb_free_urb(port->interrupt_out_urb);
- if (!IS_ERR(port->write_fifo) && port->write_fifo)
- kfifo_free(port->write_fifo);
+ kfifo_free(&port->write_fifo);
kfree(port->bulk_in_buffer);
kfree(port->bulk_out_buffer);
kfree(port->interrupt_in_buffer);
@@ -939,7 +938,7 @@ int usb_serial_probe(struct usb_interfac
dev_err(&interface->dev, "No free urbs available\n");
goto probe_error;
}
- if (kfifo_alloc(port->write_fifo, PAGE_SIZE, GFP_KERNEL))
+ if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
goto probe_error;
buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
port->bulk_out_size = buffer_size;
diff -u -N -r -p old/include/linux/usb/serial.h new/include/linux/usb/serial.h
--- old/include/linux/usb/serial.h 2009-12-23 08:54:34.368476110 +0100
+++ new/include/linux/usb/serial.h 2009-12-23 09:06:32.870725683 +0100
@@ -16,6 +16,7 @@
#include <linux/kref.h>
#include <linux/mutex.h>
#include <linux/sysrq.h>
+#include <linux/kfifo.h>
#define SERIAL_TTY_MAJOR 188 /* Nice legal number now */
#define SERIAL_TTY_MINORS 254 /* loads of devices :) */
@@ -94,7 +95,7 @@ struct usb_serial_port {
unsigned char *bulk_out_buffer;
int bulk_out_size;
struct urb *write_urb;
- struct kfifo *write_fifo;
+ struct kfifo write_fifo;
int write_urb_busy;
__u8 bulk_out_endpointAddress;
As you can see i didn't changed noting about this drain thing.
Stefani
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