2023-02-16 19:05:10

by Frank Jungclaus

Subject: [PATCH v3 2/3] 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 <[email protected]>
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/
---
drivers/net/can/usb/esd_usb.c | 50 +++++++++++++++++------------------
1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 5e182fadd875..578b25f873e5 100644
--- 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++;
+ }
}
}

--
2.25.1