Re: [PATCH v3 12/13] can: slcan: extend the protocol with error info

[Dario Binacchi <dario.binacchi@amarulasolutions.com>]

On Mon, Jun 13, 2022 at 9:32 AM Marc Kleine-Budde <mkl@pengutronix.de> wrote:
>
> On 12.06.2022 23:39:26, Dario Binacchi wrote:
> > It extends the protocol to receive the adapter CAN communication errors
> > and forward them to the netdev upper levels.
> >
> > Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> >
> > ---
> >
> > (no changes since v2)
> >
> > Changes in v2:
> > - Protect decoding against the case the len value is longer than the
> >   received data.
>
> Where is that check?

I added the default case in the switch statement. Each line that is
processed by slc_bump_err()
is terminated by a '\r' or '\a' character. If len value is longer than
the received characters, it will
enter the default case for the eol character and the function will return.
But I realize now that I am wrong, the terminator is not placed in the
buffer passed to slc_bump_err() !!!!!! :)
I will add the right check in v4.

Thanks and regards,
Dario

>
> > - Continue error handling even if no skb can be allocated.
> >
> >  drivers/net/can/slcan/slcan-core.c | 130 ++++++++++++++++++++++++++++-
> >  1 file changed, 129 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
> > index 3df35ae8f040..48077edb9497 100644
> > --- a/drivers/net/can/slcan/slcan-core.c
> > +++ b/drivers/net/can/slcan/slcan-core.c
> > @@ -175,8 +175,118 @@ int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on)
> >    *                  STANDARD SLCAN DECAPSULATION                     *
> >    ************************************************************************/
> >
> > +static void slc_bump_err(struct slcan *sl)
> > +{
> > +     struct net_device *dev = sl->dev;
> > +     struct sk_buff *skb;
> > +     struct can_frame *cf;
> > +     char *cmd = sl->rbuff;
> > +     bool rx_errors = false, tx_errors = false;
> > +     int i, len;
> > +
> > +     if (*cmd != 'e')
> > +             return;
>
> This has already been checked in the caller, right?
>
> > +
> > +     cmd += SLC_CMD_LEN;
> > +     /* get len from sanitized ASCII value */
> > +     len = *cmd++;
> > +     if (len >= '0' && len < '9')
> > +             len -= '0';
> > +     else
> > +             return;
> > +
> > +     skb = alloc_can_err_skb(dev, &cf);
> > +
> > +     if (skb)
> > +             cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> > +
> > +     for (i = 0; i < len; i++, cmd++) {
> > +             switch (*cmd) {
> > +             case 'a':
> > +                     netdev_dbg(dev, "ACK error\n");
> > +                     tx_errors = true;
>
> Nitpick:
> Please decide if you want to set tx/tx_errors here and increment at the
> end of the function....or.....
>
> > +                     if (skb) {
> > +                             cf->can_id |= CAN_ERR_ACK;
> > +                             cf->data[3] = CAN_ERR_PROT_LOC_ACK;
> > +                     }
> > +
> > +                     break;
> > +             case 'b':
> > +                     netdev_dbg(dev, "Bit0 error\n");
> > +                     tx_errors = true;
> > +                     if (skb)
> > +                             cf->data[2] |= CAN_ERR_PROT_BIT0;
> > +
> > +                     break;
> > +             case 'B':
> > +                     netdev_dbg(dev, "Bit1 error\n");
> > +                     tx_errors = true;
> > +                     if (skb)
> > +                             cf->data[2] |= CAN_ERR_PROT_BIT1;
> > +
> > +                     break;
> > +             case 'c':
> > +                     netdev_dbg(dev, "CRC error\n");
> > +                     rx_errors = true;
> > +                     if (skb) {
> > +                             cf->data[2] |= CAN_ERR_PROT_BIT;
> > +                             cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ;
> > +                     }
> > +
> > +                     break;
> > +             case 'f':
> > +                     netdev_dbg(dev, "Form Error\n");
> > +                     rx_errors = true;
> > +                     if (skb)
> > +                             cf->data[2] |= CAN_ERR_PROT_FORM;
> > +
> > +                     break;
> > +             case 'o':
> > +                     netdev_dbg(dev, "Rx overrun error\n");
> > +                     dev->stats.rx_over_errors++;
> > +                     dev->stats.rx_errors++;
>
> ....if you want to increment in the case.
>
> > +                     if (skb) {
> > +                             cf->can_id |= CAN_ERR_CRTL;
> > +                             cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
> > +                     }
> > +
> > +                     break;
> > +             case 'O':
> > +                     netdev_dbg(dev, "Tx overrun error\n");
> > +                     dev->stats.tx_errors++;
> > +                     if (skb) {
> > +                             cf->can_id |= CAN_ERR_CRTL;
> > +                             cf->data[1] = CAN_ERR_CRTL_TX_OVERFLOW;
> > +                     }
> > +
> > +                     break;
> > +             case 's':
> > +                     netdev_dbg(dev, "Stuff error\n");
> > +                     rx_errors = true;
> > +                     if (skb)
> > +                             cf->data[2] |= CAN_ERR_PROT_STUFF;
> > +
> > +                     break;
> > +             default:
> > +                     if (skb)
> > +                             dev_kfree_skb(skb);
> > +
> > +                     return;
> > +             }
> > +     }
> > +
> > +     if (rx_errors)
> > +             dev->stats.rx_errors++;
> > +
> > +     if (tx_errors)
> > +             dev->stats.tx_errors++;
> > +
> > +     if (skb)
> > +             netif_rx(skb);
> > +}
> > +
> >  /* Send one completely decapsulated can_frame to the network layer */
> > -static void slc_bump(struct slcan *sl)
> > +static void slc_bump_frame(struct slcan *sl)
> >  {
> >       struct sk_buff *skb;
> >       struct can_frame *cf;
> > @@ -255,6 +365,24 @@ static void slc_bump(struct slcan *sl)
> >       dev_kfree_skb(skb);
> >  }
> >
> > +static void slc_bump(struct slcan *sl)
> > +{
> > +     switch (sl->rbuff[0]) {
> > +     case 'r':
> > +             fallthrough;
> > +     case 't':
> > +             fallthrough;
> > +     case 'R':
> > +             fallthrough;
> > +     case 'T':
> > +             return slc_bump_frame(sl);
> > +     case 'e':
> > +             return slc_bump_err(sl);
> > +     default:
> > +             return;
> > +     }
> > +}
> > +
> >  /* parse tty input stream */
> >  static void slcan_unesc(struct slcan *sl, unsigned char s)
> >  {
> > --
> > 2.32.0
> >
> >
>
> Marc
>
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
> Embedded Linux                   | https://www.pengutronix.de  |
> Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



-- 

Dario Binacchi

Embedded Linux Developer

dario.binacchi@amarulasolutions.com

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