Hi Peter,
On Mon. 10 Apr 2023 at 14:52, Peter Hong <peter_hong@xxxxxxxxxxxxx> wrote:
> Hi Vincent,
>
> Vincent MAILHOL 於 2023/3/30 下午 09:11 寫道:
> > Hmm, I am still not a fan of setting a mutex for a single concurrency
> > issue which can only happen during probing.
> >
> > What about this:
> >
> > static int __f81604_set_termination(struct net_device *netdev, u16 term)
> > {
> > struct f81604_port_priv *port_priv = netdev_priv(netdev);
> > u8 mask, data = 0;
> >
> > if (netdev->dev_id == 0)
> > mask = F81604_CAN0_TERM;
> > else
> > mask = F81604_CAN1_TERM;
> >
> > if (term == F81604_TERMINATION_ENABLED)
> > data = mask;
> >
> > return f81604_mask_set_register(port_priv->dev, F81604_TERMINATOR_REG,
> > mask, data);
> > }
> >
> > static int f81604_set_termination(struct net_device *netdev, u16 term)
> > {
> > ASSERT_RTNL();
> >
> > return __f81604_set_termination(struct net_device *netdev, u16 term);
> > }
> >
> > static int f81604_init_termination(struct f81604_priv *priv)
> > {
> > int i, ret;
> >
> > for (i = 0; i < ARRAY_SIZE(f81604_priv->netdev); i++) {
> > ret = __f81604_set_termination(f81604_priv->netdev[i],
> > F81604_TERMINATION_DISABLED);
> > if (ret)
> > return ret;
> > }
> > }
> >
> > static int f81604_probe(struct usb_interface *intf,
> > const struct usb_device_id *id)
> > {
> > /* ... */
> >
> > err = f81604_init_termination(priv);
> > if (err)
> > goto failure_cleanup;
> >
> > for (i = 0; i < ARRAY_SIZE(f81604_priv->netdev); i++) {
> > /* ... */
> > }
> >
> > /* ... */
> > }
> >
> > Initialise all resistors with __f81604_set_termination() in probe()
> > before registering any network device. Use f81604_set_termination()
> > which has the lock assert elsewhere.
>
> The f81604_set_termination() will transform into the following code:
>
> static int f81604_write(struct usb_device *dev, u16 reg, u8 data);
> static int f81604_read(struct usb_device *dev, u16 reg, u8 *data);
> static int f81604_update_bits(struct usb_device *dev, u16 reg, u8 mask,
> u8 data);
>
> static int __f81604_set_termination(struct usb_device *dev, int idx, u16
> term)
> {
> u8 mask, data = 0;
>
> if (idx == 0)
> mask = F81604_CAN0_TERM;
> else
> mask = F81604_CAN1_TERM;
>
> if (term)
> data = mask;
>
> return f81604_update_bits(dev, F81604_TERMINATOR_REG, mask, data);
> }
>
> static int f81604_set_termination(struct net_device *netdev, u16 term)
> {
> struct f81604_port_priv *port_priv = netdev_priv(netdev);
> struct f81604_priv *priv;
>
> ASSERT_RTNL();
>
> priv = usb_get_intfdata(port_priv->intf);
^^^^
Why do you need priv here? I do not see it used in the next line.
> return __f81604_set_termination(port_priv->dev, netdev->dev_id, term);
> }
>
> and also due to f81604_write() / f81604_read() / f81604_update_bits()
> may use
> in f81604_probe() without port private data, so we'll change their first
> parameter
> from "struct f81604_port_priv *priv" to "struct usb_device *dev". Is it OK ?
Right now, it is hard to visualize the final result. Please send what
you think is the best and we will review.
> > Also, looking at your probe() function, in label clean_candev:, if the
> > second can channel fails its initialization, you do not clean the
> > first can channel. I suggest adding a f81604_init_netdev() and
> > handling the netdev issue and cleanup in that function.
>
> When the second can channel failed its initialization, the label
> "clean_candev" will
> clear second "netdev" object and the first "netdev" will cleanup in
> f81604_disconnect().
>
> Could I remain this section of code ?
Oh! I was not aware that disconnect() would be called on a failed
probe. Overall, I prefer the use of subfunctions because it makes it
easier to understand the logic, especially for the cleanup after
failure. Let's say that it is acceptable as-is. OK to keep.
