Messages in this thread | | | Date | Fri, 30 Jun 2006 12:35:30 -0400 | From | Andy Gay <> | Subject | Re: [PATCH] Airprime driver improvements to allow full speed EvDO transfers |
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On Fri, 2006-06-30 at 00:10 -0700, Andrew Morton wrote:
> > > > ... > > > > +static void airprime_read_bulk_callback(struct urb *urb, struct pt_regs *regs) > > +{ ...
> > + tty = port->tty; > > + if (tty && urb->actual_length) { > > + tty_buffer_request_room(tty, urb->actual_length); > > + tty_insert_flip_string(tty, data, urb->actual_length); > > Is it correct to ignore the return value from those two functions? Not my code :) - generic.c and several other drivers do the same thing... Not that that's an excuse, of course :) Actually though, I think it's OK to ignore the tty_insert_flip_string result. These adapters are used at layer 1 for ppp connection, the higher layers will attempt to recover.
I will remove the tty_buffer_request_room() call though, as suggested by Sergei Organov and Alan Cox.
> > > + tty_flip_buffer_push(tty); > > + } > > + /* should this use GFP_KERNEL? */ > > + result = usb_submit_urb(urb, GFP_ATOMIC); > > If possible, yep. Oops - that was a comment to myself I left in by mistake. As pointed out by Pete Zaitcev, this is a callback function. I think it has to be GFP_ATOMIC here, doesn't it?
> > > ... > > > > +static int airprime_open(struct usb_serial_port *port, struct file *filp) > > +{ > > + struct airprime_private *priv = usb_get_serial_port_data(port); > > + struct usb_serial *serial = port->serial; > > + struct urb *urb; > > + char *buffer; > > + int i; > > + int result = 0; > > + > > + dbg("%s - port %d", __FUNCTION__, port->number); > > + > > + /* initialize our private data structure if it isn't already created */ > > + if (!priv) { > > + priv = kzalloc(sizeof(*priv), GFP_KERNEL); > > + if (!priv) > > + return -ENOMEM; > > + spin_lock_init(&priv->lock); > > + usb_set_serial_port_data(port, priv); > > + } > > + /* TODO handle error conditions better, right now we leak memory */ > > + for (i = 0; i < NUM_READ_URBS; ++i) { > > + buffer = kmalloc(buffer_size, GFP_KERNEL); > > + if (!buffer) { > > + dev_err(&port->dev, "%s - out of memory.\n", > > + __FUNCTION__); > > + return -ENOMEM; > > + } > > + urb = usb_alloc_urb(0, GFP_KERNEL); > > + if (!urb) { > > + dev_err(&port->dev, "%s - no more urbs?\n", > > + __FUNCTION__); > > + return -ENOMEM; > > + } > > + usb_fill_bulk_urb(urb, serial->dev, > > + usb_rcvbulkpipe(serial->dev, > > + port->bulk_out_endpointAddress), > > + buffer, buffer_size, > > + airprime_read_bulk_callback, port); > > + result = usb_submit_urb(urb, GFP_KERNEL); > > + if (result) { > > + dev_err(&port->dev, > > + "%s - failed submitting read urb %d for port %d, error %d\n", > > + __FUNCTION__, i, port->number, result); > > + return result; > > + } > > + /* fun with reference counting, when this urb is finished, the > > + * host driver will free it up automatically */ > > + /* don't do this here, we need the urb to stay around until the close > > + function can take care of it */ > > + //usb_free_urb (urb); > > + /* instead remember this urb so we can kill it when the > > + port is closed */ > > + priv->read_urbp[i] = urb; > > + } > > + return result; > > +} > > + > > This function leaks memory all over the place if something goes wrong. Indeed. Hence the TODO comment.
> > Please redesign it to have a single `return' statement. You'll find that'll > help avoid leaks now and during any later enhancements. OK, I'll work on that. > > > > +{ > > + struct airprime_private *priv = usb_get_serial_port_data(port); > > + int i; > > + > > + dbg("%s - port %d", __FUNCTION__, port->number); > > + > > + /* killing the urb will invoke read_bulk_callback() with an error status, > > + so the transfer buffer will be freed there */ > > + for (i = 0; i < NUM_READ_URBS; ++i) { > > + usb_kill_urb (priv->read_urbp[i]); > > + usb_free_urb (priv->read_urbp[i]); > > + } > > + > > + /* free up private structure? */ > > Yes please ;) Easily done. But we'd need another one next time the port is opened. Why not just allocate it once and keep reusing it?
> > > +} > > + > > +static int airprime_write(struct usb_serial_port *port, > > + const unsigned char *buf, int count) > > +{ > > + struct airprime_private *priv = usb_get_serial_port_data(port); > > + struct usb_serial *serial = port->serial; > > + struct urb *urb; > > + unsigned char *buffer; > > + unsigned long flags; > > + int status; > > + dbg("%s - port %d", __FUNCTION__, port->number); > > + > > + spin_lock_irqsave(&priv->lock, flags); > > + if (priv->outstanding_urbs > NUM_WRITE_URBS) { > > + spin_unlock_irqrestore(&priv->lock, flags); > > + dbg("%s - write limit hit\n", __FUNCTION__); > > + return 0; > > + } > > + spin_unlock_irqrestore(&priv->lock, flags); > > + buffer = kmalloc(count, GFP_ATOMIC); > > + if (!buffer) { > > + dev_err(&port->dev, "out of memory\n"); > > + return -ENOMEM; > > + } > > + urb = usb_alloc_urb(0, GFP_ATOMIC); > > + if (!urb) { > > + dev_err(&port->dev, "no more free urbs\n"); > > + kfree (buffer); > > + return -ENOMEM; > > + } > > + memcpy (buffer, buf, count); > > + > > + usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, buffer); > > + > > + usb_fill_bulk_urb(urb, serial->dev, > > + usb_sndbulkpipe(serial->dev, > > + port->bulk_out_endpointAddress), > > + buffer, count, > > + airprime_write_bulk_callback, port); > > + > > + /* send it down the pipe */ > > + status = usb_submit_urb(urb, GFP_ATOMIC); > > + if (status) { > > + dev_err(&port->dev, > > + "%s - usb_submit_urb(write bulk) failed with status = %d\n", > > + __FUNCTION__, status); > > + count = status; > > + kfree (buffer); > > + } else { > > + spin_lock_irqsave(&priv->lock, flags); > > + ++priv->outstanding_urbs; > > + spin_unlock_irqrestore(&priv->lock, flags); > > + } > > + /* we are done with this urb, so let the host driver > > + * really free it when it is finished with it */ > > + usb_free_urb (urb); > > + return count; > > +} > > Is usb_serial_driver.write() really called in a context in which it is > forced to use GFP_ATOMIC? No idea. Safer to leave this as is, I think.
> > Again, implementing this function as single-exit would make it easier to > maintain. OK.
> > > +MODULE_PARM_DESC(debug, "Debug enabled or not"); > > Just "Debug enabled". > > > +module_param(buffer_size, int, 0); > > +MODULE_PARM_DESC(buffer_size, "Size of the transfer buffers"); > > Units? > I'll fix these. Thanks for reviewing this.
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