Re: [PATCH v4 2/4] can: kvaser_usb: Update error counters before exiting on OOM
From: Ahmed S. Darwish
Date: Mon Jan 12 2015 - 15:37:04 EST
On Mon, Jan 12, 2015 at 12:09:32PM +0100, Marc Kleine-Budde wrote:
> On 01/11/2015 09:15 PM, Ahmed S. Darwish wrote:
> > From: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx>
> >
> > Let the error counters be more accurate in case of Out of
> > Memory conditions.
>
> Please have a look at kvaser_usb_rx_error(), the whole state handling is
> omitted in case of OOM.
>
I see. Regarding kvaser_usb_rx_error(), would something like
below patch be acceptable?
Kindly note that separating recording interface state from
error frame packet building leads to duplication of a good
number of if-conditions. Meanwhile, it truly saves _all_
of the possible state before any ENOMEM -- the correct thing
to do.
Another solution was to allocate the can frame on the stack,
and thus avoiding any code duplication. But this only leads
to calls of "kvaser_usb_simple_msg_async", which can fail
with -ENOMEM by itself, returning to the very same problem
again.
If the patch is acceptable, I'll rebase my USBCAN-II driver
above it and re-submit the series (minus the merged patch).
Thanks,
-->
[ Patch is build-tested, but not _fully_ run-time tested.
It's based on linux-can/testing commit d642b49f6d84b94bd
"can: kvaser_usb: Don't dereference skb after a netif_rx" ]
Subject: [PATCH] can: kvaser_usb: Update net interface state
before exiting on OOM
From: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx>
Let the network interface can bus state and error counters be
more accurate in case of Out of Memory conditions.
Suggested-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx>
---
drivers/net/can/usb/kvaser_usb.c | 182 +++++++++++++++++++++++----------------
1 file changed, 106 insertions(+), 76 deletions(-)
diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c
index c32cd61..2d0ef76 100644
--- a/drivers/net/can/usb/kvaser_usb.c
+++ b/drivers/net/can/usb/kvaser_usb.c
@@ -273,6 +273,10 @@ struct kvaser_msg {
} u;
} __packed;
+struct kvaser_usb_error_summary {
+ u8 channel, status, txerr, rxerr, error_factor;
+};
+
struct kvaser_usb_tx_urb_context {
struct kvaser_usb_net_priv *priv;
u32 echo_index;
@@ -615,6 +619,57 @@ static void kvaser_usb_unlink_tx_urbs(struct kvaser_usb_net_priv *priv)
priv->tx_contexts[i].echo_index = MAX_TX_URBS;
}
+static void kvaser_usb_rx_error_update_state(struct kvaser_usb_net_priv *priv,
+ const struct kvaser_usb_error_summary *es)
+{
+ struct net_device_stats *stats;
+ unsigned int new_state;
+
+ stats = &priv->netdev->stats;
+ new_state = priv->can.state;
+
+ netdev_dbg(priv->netdev, "Error status: 0x%02x\n", es->status);
+
+ if (es->status & M16C_STATE_BUS_OFF) {
+ priv->can.can_stats.bus_off++;
+ new_state = CAN_STATE_BUS_OFF;
+ } else if (es->status & M16C_STATE_BUS_PASSIVE) {
+ if (priv->can.state != CAN_STATE_ERROR_PASSIVE) {
+ priv->can.can_stats.error_passive++;
+ }
+ new_state = CAN_STATE_ERROR_PASSIVE;
+ }
+
+ if (es->status == M16C_STATE_BUS_ERROR) {
+ if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
+ ((es->txerr >= 96) || (es->rxerr >= 96))) {
+ priv->can.can_stats.error_warning++;
+ new_state = CAN_STATE_ERROR_WARNING;
+ } else if (priv->can.state > CAN_STATE_ERROR_ACTIVE) {
+ new_state = CAN_STATE_ERROR_ACTIVE;
+ }
+ }
+
+ if (!es->status) {
+ new_state = CAN_STATE_ERROR_ACTIVE;
+ }
+
+ if (priv->can.restart_ms &&
+ (priv->can.state >= CAN_STATE_BUS_OFF) &&
+ (new_state < CAN_STATE_BUS_OFF)) {
+ priv->can.can_stats.restarts++;
+ }
+
+ if (es->error_factor) {
+ priv->can.can_stats.bus_error++;
+ stats->rx_errors++;
+ }
+
+ priv->bec.txerr = es->txerr;
+ priv->bec.rxerr = es->rxerr;
+ priv->can.state = new_state;
+}
+
static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
const struct kvaser_msg *msg)
{
@@ -622,30 +677,30 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
struct sk_buff *skb;
struct net_device_stats *stats;
struct kvaser_usb_net_priv *priv;
- unsigned int new_state;
- u8 channel, status, txerr, rxerr, error_factor;
+ struct kvaser_usb_error_summary es = { };
+ unsigned int new_state, old_state;
switch (msg->id) {
case CMD_CAN_ERROR_EVENT:
- channel = msg->u.error_event.channel;
- status = msg->u.error_event.status;
- txerr = msg->u.error_event.tx_errors_count;
- rxerr = msg->u.error_event.rx_errors_count;
- error_factor = msg->u.error_event.error_factor;
+ es.channel = msg->u.error_event.channel;
+ es.status = msg->u.error_event.status;
+ es.txerr = msg->u.error_event.tx_errors_count;
+ es.rxerr = msg->u.error_event.rx_errors_count;
+ es.error_factor = msg->u.error_event.error_factor;
break;
case CMD_LOG_MESSAGE:
- channel = msg->u.log_message.channel;
- status = msg->u.log_message.data[0];
- txerr = msg->u.log_message.data[2];
- rxerr = msg->u.log_message.data[3];
- error_factor = msg->u.log_message.data[1];
+ es.channel = msg->u.log_message.channel;
+ es.status = msg->u.log_message.data[0];
+ es.txerr = msg->u.log_message.data[2];
+ es.rxerr = msg->u.log_message.data[3];
+ es.error_factor = msg->u.log_message.data[1];
break;
case CMD_CHIP_STATE_EVENT:
- channel = msg->u.chip_state_event.channel;
- status = msg->u.chip_state_event.status;
- txerr = msg->u.chip_state_event.tx_errors_count;
- rxerr = msg->u.chip_state_event.rx_errors_count;
- error_factor = 0;
+ es.channel = msg->u.chip_state_event.channel;
+ es.status = msg->u.chip_state_event.status;
+ es.txerr = msg->u.chip_state_event.tx_errors_count;
+ es.rxerr = msg->u.chip_state_event.rx_errors_count;
+ es.error_factor = 0;
break;
default:
dev_err(dev->udev->dev.parent, "Invalid msg id (%d)\n",
@@ -653,122 +708,97 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev,
return;
}
- if (channel >= dev->nchannels) {
+ if (es.channel >= dev->nchannels) {
dev_err(dev->udev->dev.parent,
- "Invalid channel number (%d)\n", channel);
+ "Invalid channel number (%d)\n", es.channel);
return;
}
- priv = dev->nets[channel];
+ priv = dev->nets[es.channel];
stats = &priv->netdev->stats;
- if (status & M16C_STATE_BUS_RESET) {
+ if (es.status & M16C_STATE_BUS_RESET) {
kvaser_usb_unlink_tx_urbs(priv);
return;
}
+ old_state = priv->can.state;
+ kvaser_usb_rx_error_update_state(priv, &es);
+ new_state = priv->can.state;
+
skb = alloc_can_err_skb(priv->netdev, &cf);
if (!skb) {
stats->rx_dropped++;
return;
}
- new_state = priv->can.state;
-
- netdev_dbg(priv->netdev, "Error status: 0x%02x\n", status);
-
- if (status & M16C_STATE_BUS_OFF) {
- cf->can_id |= CAN_ERR_BUSOFF;
-
- priv->can.can_stats.bus_off++;
+ if (es.status & M16C_STATE_BUS_OFF) {
if (!priv->can.restart_ms)
kvaser_usb_simple_msg_async(priv, CMD_STOP_CHIP);
-
netif_carrier_off(priv->netdev);
- new_state = CAN_STATE_BUS_OFF;
- } else if (status & M16C_STATE_BUS_PASSIVE) {
- if (priv->can.state != CAN_STATE_ERROR_PASSIVE) {
+ cf->can_id |= CAN_ERR_BUSOFF;
+ } else if (es.status & M16C_STATE_BUS_PASSIVE) {
+ if (old_state != CAN_STATE_ERROR_PASSIVE) {
cf->can_id |= CAN_ERR_CRTL;
- if (txerr || rxerr)
- cf->data[1] = (txerr > rxerr)
+ if (es.txerr || es.rxerr)
+ cf->data[1] = (es.txerr > es.rxerr)
? CAN_ERR_CRTL_TX_PASSIVE
: CAN_ERR_CRTL_RX_PASSIVE;
else
cf->data[1] = CAN_ERR_CRTL_TX_PASSIVE |
CAN_ERR_CRTL_RX_PASSIVE;
-
- priv->can.can_stats.error_passive++;
}
-
- new_state = CAN_STATE_ERROR_PASSIVE;
}
- if (status == M16C_STATE_BUS_ERROR) {
- if ((priv->can.state < CAN_STATE_ERROR_WARNING) &&
- ((txerr >= 96) || (rxerr >= 96))) {
+ if (es.status == M16C_STATE_BUS_ERROR) {
+ if ((old_state < CAN_STATE_ERROR_WARNING) &&
+ ((es.txerr >= 96) || (es.rxerr >= 96))) {
cf->can_id |= CAN_ERR_CRTL;
- cf->data[1] = (txerr > rxerr)
+ cf->data[1] = (es.txerr > es.rxerr)
? CAN_ERR_CRTL_TX_WARNING
: CAN_ERR_CRTL_RX_WARNING;
-
- priv->can.can_stats.error_warning++;
- new_state = CAN_STATE_ERROR_WARNING;
- } else if (priv->can.state > CAN_STATE_ERROR_ACTIVE) {
+ } else if (old_state > CAN_STATE_ERROR_ACTIVE) {
cf->can_id |= CAN_ERR_PROT;
cf->data[2] = CAN_ERR_PROT_ACTIVE;
-
- new_state = CAN_STATE_ERROR_ACTIVE;
}
}
- if (!status) {
+ if (!es.status) {
cf->can_id |= CAN_ERR_PROT;
cf->data[2] = CAN_ERR_PROT_ACTIVE;
-
- new_state = CAN_STATE_ERROR_ACTIVE;
}
if (priv->can.restart_ms &&
- (priv->can.state >= CAN_STATE_BUS_OFF) &&
+ (old_state >= CAN_STATE_BUS_OFF) &&
(new_state < CAN_STATE_BUS_OFF)) {
cf->can_id |= CAN_ERR_RESTARTED;
netif_carrier_on(priv->netdev);
-
- priv->can.can_stats.restarts++;
}
- if (error_factor) {
- priv->can.can_stats.bus_error++;
- stats->rx_errors++;
-
+ if (es.error_factor) {
cf->can_id |= CAN_ERR_BUSERROR | CAN_ERR_PROT;
- if (error_factor & M16C_EF_ACKE)
+ if (es.error_factor & M16C_EF_ACKE)
cf->data[3] |= (CAN_ERR_PROT_LOC_ACK);
- if (error_factor & M16C_EF_CRCE)
+ if (es.error_factor & M16C_EF_CRCE)
cf->data[3] |= (CAN_ERR_PROT_LOC_CRC_SEQ |
CAN_ERR_PROT_LOC_CRC_DEL);
- if (error_factor & M16C_EF_FORME)
+ if (es.error_factor & M16C_EF_FORME)
cf->data[2] |= CAN_ERR_PROT_FORM;
- if (error_factor & M16C_EF_STFE)
+ if (es.error_factor & M16C_EF_STFE)
cf->data[2] |= CAN_ERR_PROT_STUFF;
- if (error_factor & M16C_EF_BITE0)
+ if (es.error_factor & M16C_EF_BITE0)
cf->data[2] |= CAN_ERR_PROT_BIT0;
- if (error_factor & M16C_EF_BITE1)
+ if (es.error_factor & M16C_EF_BITE1)
cf->data[2] |= CAN_ERR_PROT_BIT1;
- if (error_factor & M16C_EF_TRE)
+ if (es.error_factor & M16C_EF_TRE)
cf->data[2] |= CAN_ERR_PROT_TX;
}
- cf->data[6] = txerr;
- cf->data[7] = rxerr;
-
- priv->bec.txerr = txerr;
- priv->bec.rxerr = rxerr;
-
- priv->can.state = new_state;
+ cf->data[6] = es.txerr;
+ cf->data[7] = es.rxerr;
stats->rx_packets++;
stats->rx_bytes += cf->can_dlc;
@@ -792,6 +822,9 @@ static void kvaser_usb_rx_can_err(const struct kvaser_usb_net_priv *priv,
}
if (msg->u.rx_can.flag & MSG_FLAG_OVERRUN) {
+ stats->rx_over_errors++;
+ stats->rx_errors++;
+
skb = alloc_can_err_skb(priv->netdev, &cf);
if (!skb) {
stats->rx_dropped++;
@@ -801,9 +834,6 @@ static void kvaser_usb_rx_can_err(const struct kvaser_usb_net_priv *priv,
cf->can_id |= CAN_ERR_CRTL;
cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
- stats->rx_over_errors++;
- stats->rx_errors++;
-
stats->rx_packets++;
stats->rx_bytes += cf->can_dlc;
netif_rx(skb);
--
1.9.1
--
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