Re: [PATCH v3 2/5] can: kvaser_usb: do not increase tx statistics when sending error message frames
From: Jimmy Assarsson
Date: Fri Dec 03 2021 - 03:45:35 EST
On 2021-12-03 05:02, Vincent MAILHOL wrote:
On Fri. 3 Dec 2021 at 08:35, Jimmy Assarsson <extja@xxxxxxxxxx> wrote:
On 2021-11-28 13:37, Vincent Mailhol wrote:
The CAN error message frames (i.e. error skb) are an interface
specific to socket CAN. The payload of the CAN error message frames
does not correspond to any actual data sent on the wire. Only an error
flag and a delimiter are transmitted when an error occurs (c.f. ISO
11898-1 section 10.4.4.2 "Error flag").
For this reason, it makes no sense to increment the tx_packets and
tx_bytes fields of struct net_device_stats when sending an error
message frame because no actual payload will be transmitted on the
wire.
N.B. Sending error message frames is a very specific feature which, at
the moment, is only supported by the Kvaser Hydra hardware. Please
refer to [1] for more details on the topic.
[1] https://lore.kernel.org/linux-can/CAMZ6RqK0rTNg3u3mBpZOoY51jLZ-et-J01tY6-+mWsM4meVw-A@xxxxxxxxxxxxxx/t/#u
CC: Jimmy Assarsson <extja@xxxxxxxxxx>
Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
Hi Vincent!
Thanks for the patch.
There are flags in the TX ACK package, which makes it possible to
determine if it was an error frame or not. So we don't need to get
the original CAN frame to determine this.
I suggest the following change:
This is a great suggestion. I was not a fan of getting the
original CAN frame, this TX ACK solves the issue.
---
.../net/can/usb/kvaser_usb/kvaser_usb_hydra.c | 25 ++++++++++++-------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
index 3398da323126..01b076f04e26 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
@@ -295,6 +295,7 @@ struct kvaser_cmd {
#define KVASER_USB_HYDRA_CF_FLAG_OVERRUN BIT(1)
#define KVASER_USB_HYDRA_CF_FLAG_REMOTE_FRAME BIT(4)
#define KVASER_USB_HYDRA_CF_FLAG_EXTENDED_ID BIT(5)
+#define KVASER_USB_HYDRA_CF_FLAG_TX_ACK BIT(6)
/* CAN frame flags. Used in ext_rx_can and ext_tx_can */
#define KVASER_USB_HYDRA_CF_FLAG_OSM_NACK BIT(12)
#define KVASER_USB_HYDRA_CF_FLAG_ABL BIT(13)
@@ -1112,7 +1113,9 @@ static void kvaser_usb_hydra_tx_acknowledge(const
struct kvaser_usb *dev,
struct kvaser_usb_tx_urb_context *context;
struct kvaser_usb_net_priv *priv;
unsigned long irq_flags;
+ unsigned int len;
bool one_shot_fail = false;
+ bool is_err_frame = false;
u16 transid = kvaser_usb_hydra_get_cmd_transid(cmd);
priv = kvaser_usb_hydra_net_priv_from_cmd(dev, cmd);
@@ -1131,24 +1134,28 @@ static void
kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
kvaser_usb_hydra_one_shot_fail(priv, cmd_ext);
one_shot_fail = true;
}
- }
-
- context = &priv->tx_contexts[transid % dev->max_tx_urbs];
- if (!one_shot_fail) {
- struct net_device_stats *stats = &priv->netdev->stats;
-
- stats->tx_packets++;
- stats->tx_bytes += can_fd_dlc2len(context->dlc);
+ if (flags & KVASER_USB_HYDRA_CF_FLAG_TX_ACK &&
+ flags & KVASER_USB_HYDRA_CF_FLAG_ERROR_FRAME)
+ is_err_frame = true;
Nitpick, but I prefer to write:
+ is_err_frame = flags & KVASER_USB_HYDRA_CF_FLAG_TX_ACK &&
+ flags & KVASER_USB_HYDRA_CF_FLAG_ERROR_FRAME;
Agree, I also prefer this.
}
spin_lock_irqsave(&priv->tx_contexts_lock, irq_flags);
- can_get_echo_skb(priv->netdev, context->echo_index, NULL);
+ context = &priv->tx_contexts[transid % dev->max_tx_urbs];
+ len = can_get_echo_skb(priv->netdev, context->echo_index, NULL);
This line is related to the tx RTR. I will rebase this into
"can: do not increase rx_bytes statistics for RTR frames" (patch 4/5).
+
context->echo_index = dev->max_tx_urbs;
--priv->active_tx_contexts;
netif_wake_queue(priv->netdev);
spin_unlock_irqrestore(&priv->tx_contexts_lock, irq_flags);
+
+ if (!one_shot_fail && !is_err_frame) {
+ struct net_device_stats *stats = &priv->netdev->stats;
+
+ stats->tx_packets++;
+ stats->tx_bytes += len;
+ }
Same here, there is no need anymore to move this block *in this
patch*, will rebase it.
Agree.
}
static void kvaser_usb_hydra_rx_msg_std(const struct kvaser_usb *dev,
This patch ("can: kvaser_usb: do not increase tx statistics when
sending error message frames") will become:
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
index 3398da323126..75009d38f8e3 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
@@ -295,6 +295,7 @@ struct kvaser_cmd {
#define KVASER_USB_HYDRA_CF_FLAG_OVERRUN BIT(1)
#define KVASER_USB_HYDRA_CF_FLAG_REMOTE_FRAME BIT(4)
#define KVASER_USB_HYDRA_CF_FLAG_EXTENDED_ID BIT(5)
+#define KVASER_USB_HYDRA_CF_FLAG_TX_ACK BIT(6)
/* CAN frame flags. Used in ext_rx_can and ext_tx_can */
#define KVASER_USB_HYDRA_CF_FLAG_OSM_NACK BIT(12)
#define KVASER_USB_HYDRA_CF_FLAG_ABL BIT(13)
@@ -1113,6 +1114,7 @@ static void
kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
struct kvaser_usb_net_priv *priv;
unsigned long irq_flags;
bool one_shot_fail = false;
+ bool is_err_frame = false;
u16 transid = kvaser_usb_hydra_get_cmd_transid(cmd);
priv = kvaser_usb_hydra_net_priv_from_cmd(dev, cmd);
@@ -1131,10 +1133,13 @@ static void
kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
kvaser_usb_hydra_one_shot_fail(priv, cmd_ext);
one_shot_fail = true;
}
+
+ is_err_frame = flags & KVASER_USB_HYDRA_CF_FLAG_TX_ACK &&
+ flags & KVASER_USB_HYDRA_CF_FLAG_ERROR_FRAME;
}
context = &priv->tx_contexts[transid % dev->max_tx_urbs];
- if (!one_shot_fail) {
+ if (!one_shot_fail && !is_err_frame) {
struct net_device_stats *stats = &priv->netdev->stats;
stats->tx_packets++;
And patch 5/5 ("can: do not increase tx_bytes
statistics for RTR frames") becomes:
diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
index 75009d38f8e3..2cb35bd162a4 100644
--- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
+++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
@@ -1113,6 +1113,7 @@ static void
kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
struct kvaser_usb_tx_urb_context *context;
struct kvaser_usb_net_priv *priv;
unsigned long irq_flags;
+ unsigned int len;
bool one_shot_fail = false;
bool is_err_frame = false;
u16 transid = kvaser_usb_hydra_get_cmd_transid(cmd);
@@ -1139,21 +1140,23 @@ static void
kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
}
context = &priv->tx_contexts[transid % dev->max_tx_urbs];
- if (!one_shot_fail && !is_err_frame) {
- struct net_device_stats *stats = &priv->netdev->stats;
-
- stats->tx_packets++;
- stats->tx_bytes += can_fd_dlc2len(context->dlc);
- }
spin_lock_irqsave(&priv->tx_contexts_lock, irq_flags);
- can_get_echo_skb(priv->netdev, context->echo_index, NULL);
+ len = can_get_echo_skb(priv->netdev, context->echo_index, NULL);
context->echo_index = dev->max_tx_urbs;
--priv->active_tx_contexts;
netif_wake_queue(priv->netdev);
spin_unlock_irqrestore(&priv->tx_contexts_lock, irq_flags);
+
+ if (!one_shot_fail && !is_err_frame) {
+ struct net_device_stats *stats = &priv->netdev->stats;
+
+ stats->tx_packets++;
+ stats->tx_bytes += len;
+ }
}
Does this look good to you? If so, can I add these tags to patch 2/5?
Co-developed-by: Jimmy Assarsson <extja@xxxxxxxxxx>
Signed-off-by: Jimmy Assarsson <extja@xxxxxxxxxx>
Yes.
Also, can I add your tested-by to patches 1/5, 4/5 and 5/5?
Tested-by: Jimmy Assarsson <extja@xxxxxxxxxx>
Yes.
Yours sincerely,
Vincent Mailhol
Thanks!
Best regards,
jimmy