netdev - RE: [PATCH v3] can: Add driver for esd CAN-USB/2 device

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Message-ID: <70376CA23424B34D86F1C7DE6B9973430254343AD9@VSHINMSMBX01.vshodc.lntinfotech.com>
Date:	Wed, 26 May 2010 17:01:23 +0530
From:	Viral Mehta <Viral.Mehta@...infotech.com>
To:	Matthias Fuchs <matthias.fuchs@....eu>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:	"Socketcan-core@...ts.berlios.de" <Socketcan-core@...ts.berlios.de>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [PATCH v3] can: Add driver for esd CAN-USB/2 device

Hi,
>________________________________________
>From: linux-usb-owner@...r.kernel.org [linux-usb-owner@...r.kernel.org] On Behalf Of Matthias Fuchs [matthias.fuchs@....eu]
>Sent: Wednesday, May 26, 2010 2:44 PM
>To: netdev@...r.kernel.org
>Cc: Socketcan-core@...ts.berlios.de; linux-usb@...r.kernel.org
>Subject: [PATCH v3] can: Add driver for esd CAN-USB/2 device
>
>This patch adds a driver for esd's USB high speed
>CAN interface. The driver supports devices with
>multiple CAN interfaces.
>
>Signed-off-by: Matthias Fuchs <matthias.fuchs@....eu>
>---

>+static void esd_usb2_write_bulk_callback(struct urb *urb)
>+{
>+       struct esd_tx_urb_context *context = urb->context;
>+       struct esd_usb2_net_priv *priv;
>+       struct esd_usb2 *dev;
>+       struct net_device *netdev;
>+       size_t size = sizeof(struct esd_usb2_msg);
>+
>+       BUG_ON(!context);

It is preferred to used WARN_ON and avoid using BUG_ON and thus dont kill the whole system....
[...]
>+
>+       priv = context->priv;
>+       netdev = priv->netdev;
>+       dev = priv->usb2;
>+       err = usb_submit_urb(urb, GFP_ATOMIC);
>+       if (err) {
>+               can_free_echo_skb(netdev, context->echo_index);
>+
>+               atomic_dec(&priv->active_tx_jobs);
>+               usb_unanchor_urb(urb);
>+
>+               stats->tx_dropped++;
>+
>+               if (err == -ENODEV)
>+                       netif_device_detach(netdev);
>+               else
>+                       dev_warn(netdev->dev.parent, "failed tx_urb %d\n", err);
>+
>+               goto releasebuf;

You probably want to set "ret" here or do you really want to return NETDEV_TX_OK
>+       }

[...]
>+static int esd_usb2_close(struct net_device *netdev)
>+{
>+       struct esd_usb2_net_priv *priv = netdev_priv(netdev);
>+       struct esd_usb2_msg msg;
>+       int i;
>+
>+       /* Disable all IDs (see esd_usb2_start()) */
>+       msg.msg.hdr.cmd = CMD_IDADD;
>+       msg.msg.hdr.len = 2 + ESD_MAX_ID_SEGMENT;
>+       msg.msg.filter.net = priv->index;
>+       msg.msg.filter.option = ESD_ID_ENABLE; /* start with segment 0 */
>+       for (i = 0; i <= ESD_MAX_ID_SEGMENT; i++)
>+               msg.msg.filter.mask[i] = 0;
>+       esd_usb2_send_msg(priv->usb2, &msg);

Probably, you may not care but it can return error value....
>+
>+       /* set CAN controller to reset mode */
>+       msg.msg.hdr.len = 2;
>+       msg.msg.hdr.cmd = CMD_SETBAUD;
>+       msg.msg.setbaud.net = priv->index;
>+       msg.msg.setbaud.rsvd = 0;
>+       msg.msg.setbaud.baud = cpu_to_le32(ESD_USB2_NO_BAUDRATE);
>+       esd_usb2_send_msg(priv->usb2, &msg);

Probably, you may not care but it can return error value....

>+
>+       priv->can.state = CAN_STATE_STOPPED;
>+
>+       netif_stop_queue(netdev);
>+
>+       close_candev(netdev);
>+

[...]
>+static int esd_usb2_probe(struct usb_interface *intf,
>+                        const struct usb_device_id *id)
>+{
>+       struct esd_usb2 *dev;
>+       struct esd_usb2_msg msg;
>+       int i, err = -ENOMEM;
>+
>+       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>+       if (!dev)
>+               return -ENOMEM;

You probably would like to rewrite "return" statements.... for example, above you define err=-ENOMEM
and then here you are saying "return -ENOMEM" later on at the end you are saying "return err";

Also, people prefer and practice to have only one return point. Read further.

>+
>+       dev->udev = interface_to_usbdev(intf);
>+
>+       init_usb_anchor(&dev->rx_submitted);
>+
>+       usb_set_intfdata(intf, dev);
>+
>+       /* query number of CAN interfaces (nets) */
>+       msg.msg.hdr.cmd = CMD_VERSION;
>+       msg.msg.hdr.len = 2;
>+       msg.msg.version.rsvd = 0;
>+       msg.msg.version.flags = 0;
>+       msg.msg.version.drv_version = 0;
>+
>+       if (esd_usb2_send_msg(dev, &msg) < 0) {
>+               dev_err(&intf->dev, "sending version message failed\n");
>+               goto free_dev;

You might like to set "err" here, since you are not propogating error values properly.....
Irrespective of what esd_usb2_send_msg and thus in turn usb_bulk_msg returns,
you are ignoring those values and always returning -ENOMEM at the end......
>+       }
>+
>+       if (esd_usb2_wait_msg(dev, &msg) < 0) {
>+               dev_err(&intf->dev, "no version message answer\n");
>+               goto free_dev;

Same here.

>+free_dev:
>+       kfree(dev);
>+       return err;
>+}

HTH,
Viral Mehta

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