can: esd_usb: Make use of can_change_state() and relocate checking skb for NULL

Start a rework initiated by Vincents remarks "You should not report
the greatest of txerr and rxerr but the one which actually increased."
[1] and "As far as I understand, those flags should be set only when
the threshold is reached" [2] .

Therefore make use of can_change_state() to (among others) set the
flags CAN_ERR_CRTL_[RT]X_WARNING and CAN_ERR_CRTL_[RT]X_PASSIVE,
maintain CAN statistic counters for error_warning, error_passive and
bus_off.

Relocate testing alloc_can_err_skb() for NULL to the end of
esd_usb_rx_event(), to have things like can_bus_off(),
can_change_state() working even in out of memory conditions.

Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
Signed-off-by: Frank Jungclaus <frank.jungclaus@esd.eu>
Link: [1] https://lore.kernel.org/all/CAMZ6RqKGBWe15aMkf8-QLf-cOQg99GQBebSm+1wEzTqHgvmNuw@mail.gmail.com/
Link: [2] https://lore.kernel.org/all/CAMZ6Rq+QBO1yTX_o6GV0yhdBj-RzZSRGWDZBS0fs7zbSTy4hmA@mail.gmail.com/
Link: https://lore.kernel.org/all/20230216190450.3901254-3-frank.jungclaus@esd.eu
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 5e182fadd875ee654b3c23a29d6d3e04036596b6..578b25f873e589217acb9ca3120276f177431c12 100644 (file)
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -239,41 +239,42 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
                           msg->msg.rx.dlc, state, ecc, rxerr, txerr);
 
                skb = alloc_can_err_skb(priv->netdev, &cf);
-               if (skb == NULL) {
-                       stats->rx_dropped++;
-                       return;
-               }
 
                if (state != priv->old_state) {
+                       enum can_state tx_state, rx_state;
+                       enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
+
                        priv->old_state = state;
 
                        switch (state & ESD_BUSSTATE_MASK) {
                        case ESD_BUSSTATE_BUSOFF:
-                               priv->can.state = CAN_STATE_BUS_OFF;
-                               cf->can_id |= CAN_ERR_BUSOFF;
-                               priv->can.can_stats.bus_off++;
+                               new_state = CAN_STATE_BUS_OFF;
                                can_bus_off(priv->netdev);
                                break;
                        case ESD_BUSSTATE_WARN:
-                               priv->can.state = CAN_STATE_ERROR_WARNING;
-                               priv->can.can_stats.error_warning++;
+                               new_state = CAN_STATE_ERROR_WARNING;
                                break;
                        case ESD_BUSSTATE_ERRPASSIVE:
-                               priv->can.state = CAN_STATE_ERROR_PASSIVE;
-                               priv->can.can_stats.error_passive++;
+                               new_state = CAN_STATE_ERROR_PASSIVE;
                                break;
                        default:
-                               priv->can.state = CAN_STATE_ERROR_ACTIVE;
+                               new_state = CAN_STATE_ERROR_ACTIVE;
                                txerr = 0;
                                rxerr = 0;
                                break;
                        }
-               } else {
+
+                       if (new_state != priv->can.state) {
+                               tx_state = (txerr >= rxerr) ? new_state : 0;
+                               rx_state = (txerr <= rxerr) ? new_state : 0;
+                               can_change_state(priv->netdev, cf,
+                                                tx_state, rx_state);
+                       }
+               } else if (skb) {
                        priv->can.can_stats.bus_error++;
                        stats->rx_errors++;
 
-                       cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR |
-                                     CAN_ERR_CNT;
+                       cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
 
                        switch (ecc & SJA1000_ECC_MASK) {
                        case SJA1000_ECC_BIT:
@@ -295,21 +296,20 @@ static void esd_usb_rx_event(struct esd_usb_net_priv *priv,
 
                        /* Bit stream position in CAN frame as the error was detected */
                        cf->data[3] = ecc & SJA1000_ECC_SEG;
-
-                       if (priv->can.state == CAN_STATE_ERROR_WARNING ||
-                           priv->can.state == CAN_STATE_ERROR_PASSIVE) {
-                               cf->data[1] = (txerr > rxerr) ?
-                                       CAN_ERR_CRTL_TX_PASSIVE :
-                                       CAN_ERR_CRTL_RX_PASSIVE;
-                       }
-                       cf->data[6] = txerr;
-                       cf->data[7] = rxerr;
                }
 
                priv->bec.txerr = txerr;
                priv->bec.rxerr = rxerr;
 
-               netif_rx(skb);
+               if (skb) {
+                       cf->can_id |= CAN_ERR_CNT;
+                       cf->data[6] = txerr;
+                       cf->data[7] = rxerr;
+
+                       netif_rx(skb);
+               } else {
+                       stats->rx_dropped++;
+               }
        }
 }