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Message-ID: <CAMZ6RqJ4WWAZSrk1AqS=TFbyrx7Ys49=fN-GTxkwh62GCS8Rqw@mail.gmail.com>
Date: Fri, 3 Dec 2021 10:05:18 +0900
From: Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To: Jimmy Assarsson <extja@...ser.com>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>, linux-can@...r.kernel.org,
Oliver Hartkopp <socketcan@...tkopp.net>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
Nicolas Ferre <nicolas.ferre@...rochip.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Ludovic Desroches <ludovic.desroches@...rochip.com>,
Maxime Ripard <mripard@...nel.org>,
Chen-Yu Tsai <wens@...e.org>,
Jernej Skrabec <jernej.skrabec@...il.com>,
Yasushi SHOJI <yashi@...cecubics.com>,
Stephane Grosjean <s.grosjean@...k-system.com>
Subject: Re: [PATCH v3 5/5] can: do not increase tx_bytes statistics for RTR frames
On Fri. 3 Dec. 2021 at 08:35, Jimmy Assarsson <extja@...ser.com> wrote:
> On 2021-11-28 13:37, Vincent Mailhol wrote:
> > The actual payload length of the CAN Remote Transmission Request (RTR)
> > frames is always 0, i.e. nothing is transmitted on the wire. However,
> > those RTR frames still use the DLC to indicate the length of the
> > requested frame.
> >
> > As such, net_device_stats:tx_bytes should not be increased when
> > sending RTR frames.
> >
> > The function can_get_echo_skb() already returns the correct length,
> > even for RTR frames (c.f. [1]). However, for historical reasons, the
> > drivers do not use can_get_echo_skb()'s return value and instead, most
> > of them store a temporary length (or dlc) in some local structure or
> > array. Using the return value of can_get_echo_skb() solves the
> > issue. After doing this, such length/dlc fields become unused and so
> > this patch does the adequate cleaning when needed.
> >
> > This patch fixes all the CAN drivers.
> >
> > Finally, can_get_echo_skb() is decorated with the __must_check
> > attribute in order to force future drivers to correctly use its return
> > value (else the compiler would emit a warning).
> >
> > [1] commit ed3320cec279 ("can: dev: __can_get_echo_skb():
> > fix real payload length return value for RTR frames")
>
> Hi Vincent!
>
> Thanks for the patch!
> I've reviewed and tested the changes affecting kvaser_usb.
> Looks good to me, only a minor nitpick inline :)
>
[...]
> > diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> > index 390b6bde883c..3a49257f9fa6 100644
> > --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> > +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb.h
> > @@ -77,7 +77,6 @@ struct kvaser_usb_dev_card_data {
> > struct kvaser_usb_tx_urb_context {
> > struct kvaser_usb_net_priv *priv;
> > u32 echo_index;
> > - int dlc;
> > };
> >
> > struct kvaser_usb {
> > @@ -162,8 +161,8 @@ struct kvaser_usb_dev_ops {
> > void (*dev_read_bulk_callback)(struct kvaser_usb *dev, void *buf,
> > int len);
> > void *(*dev_frame_to_cmd)(const struct kvaser_usb_net_priv *priv,
> > - const struct sk_buff *skb, int *frame_len,
> > - int *cmd_len, u16 transid);
> > + const struct sk_buff *skb, int *cmd_len,
> > + u16 transid);
> > };
> >
> > struct kvaser_usb_dev_cfg {
> > diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> > index 3e682ef43f8e..c4b4d3d0a387 100644
> > --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> > +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
> > @@ -565,7 +565,7 @@ static netdev_tx_t kvaser_usb_start_xmit(struct sk_buff *skb,
> > goto freeurb;
> > }
> >
> > - buf = dev->ops->dev_frame_to_cmd(priv, skb, &context->dlc, &cmd_len,
> > + buf = dev->ops->dev_frame_to_cmd(priv, skb, &cmd_len,
> > context->echo_index);
> > if (!buf) {
> > stats->tx_dropped++;
> > 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 17fabd3d0613..9f423a5fb63f 100644
> > --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
> > +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_hydra.c
> > @@ -1113,7 +1113,7 @@ static void kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
> > struct kvaser_usb_net_priv *priv;
> > struct can_frame *cf;
> > unsigned long irq_flags;
> > - int len;
> > + unsigned int len;
> > bool one_shot_fail = false, is_err_frame = false;
> > u16 transid = kvaser_usb_hydra_get_cmd_transid(cmd);
> >
> > @@ -1136,7 +1136,6 @@ static void kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
> > }
> >
> > context = &priv->tx_contexts[transid % dev->max_tx_urbs];
> > - len = context->dlc;
> >
> > spin_lock_irqsave(&priv->tx_contexts_lock, irq_flags);
> >
> > @@ -1144,7 +1143,8 @@ static void kvaser_usb_hydra_tx_acknowledge(const struct kvaser_usb *dev,
> > if (cf)
> > is_err_frame = !!(cf->can_id & CAN_RTR_FLAG);
> >
> > - 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);
> > @@ -1375,8 +1375,8 @@ static void kvaser_usb_hydra_handle_cmd(const struct kvaser_usb *dev,
> >
> > static void *
> > kvaser_usb_hydra_frame_to_cmd_ext(const struct kvaser_usb_net_priv *priv,
> > - const struct sk_buff *skb, int *frame_len,
> > - int *cmd_len, u16 transid)
> > + const struct sk_buff *skb, int *cmd_len,
> > + u16 transid)
> > {
> > struct kvaser_usb *dev = priv->dev;
> > struct kvaser_cmd_ext *cmd;
> > @@ -1388,8 +1388,6 @@ kvaser_usb_hydra_frame_to_cmd_ext(const struct kvaser_usb_net_priv *priv,
> > u32 kcan_id;
> > u32 kcan_header;
> >
> > - *frame_len = nbr_of_bytes;
> > -
> > cmd = kcalloc(1, sizeof(struct kvaser_cmd_ext), GFP_ATOMIC);
> > if (!cmd)
> > return NULL;
> > @@ -1455,8 +1453,8 @@ kvaser_usb_hydra_frame_to_cmd_ext(const struct kvaser_usb_net_priv *priv,
> >
> > static void *
> > kvaser_usb_hydra_frame_to_cmd_std(const struct kvaser_usb_net_priv *priv,
> > - const struct sk_buff *skb, int *frame_len,
> > - int *cmd_len, u16 transid)
> > + const struct sk_buff *skb, int *cmd_len,
> > + u16 transid)
> > {
> > struct kvaser_usb *dev = priv->dev;
> > struct kvaser_cmd *cmd;
> > @@ -1464,8 +1462,6 @@ kvaser_usb_hydra_frame_to_cmd_std(const struct kvaser_usb_net_priv *priv,
> > u32 flags;
> > u32 id;
> >
> > - *frame_len = cf->len;
> > -
> > cmd = kcalloc(1, sizeof(struct kvaser_cmd), GFP_ATOMIC);
> > if (!cmd)
> > return NULL;
> > @@ -1493,13 +1489,13 @@ kvaser_usb_hydra_frame_to_cmd_std(const struct kvaser_usb_net_priv *priv,
> > if (cf->can_id & CAN_RTR_FLAG)
> > flags |= KVASER_USB_HYDRA_CF_FLAG_REMOTE_FRAME;
> >
> > - flags |= (cf->can_id & CAN_ERR_FLAG ?
> > - KVASER_USB_HYDRA_CF_FLAG_ERROR_FRAME : 0);
> > + if (cf->can_id & CAN_ERR_FLAG)
> > + flags |= KVASER_USB_HYDRA_CF_FLAG_ERROR_FRAME;
>
> This has nothing to do with RTR. Maybe put it in a separate patch?
Arg... You are right. This should not be here. I saw it in my
final check, removed it in my tree and forgot to redo a "git
format-patch".
This is some leftover of a previous version in which I did more
heavy changes to kvaser_usb_hydra_frame_to_cmd_std(). This is
purely cosmetic though. I am not willing to go into a clean up
crusade of all CAN drivers so I will just leave the ternary
operator untouched. Free to you to reuse it if you want to do a
clean up later on.
> >
> > cmd->tx_can.id = cpu_to_le32(id);
> > cmd->tx_can.flags = flags;
> >
> > - memcpy(cmd->tx_can.data, cf->data, *frame_len);
> > + memcpy(cmd->tx_can.data, cf->data, cf->len);
> >
> > return cmd;
> > }
> > @@ -2007,17 +2003,17 @@ static void kvaser_usb_hydra_read_bulk_callback(struct kvaser_usb *dev,
> >
> > static void *
> > kvaser_usb_hydra_frame_to_cmd(const struct kvaser_usb_net_priv *priv,
> > - const struct sk_buff *skb, int *frame_len,
> > - int *cmd_len, u16 transid)
> > + const struct sk_buff *skb, int *cmd_len,
> > + u16 transid)
> > {
> > void *buf;
> >
> > if (priv->dev->card_data.capabilities & KVASER_USB_HYDRA_CAP_EXT_CMD)
> > - buf = kvaser_usb_hydra_frame_to_cmd_ext(priv, skb, frame_len,
> > - cmd_len, transid);
> > + buf = kvaser_usb_hydra_frame_to_cmd_ext(priv, skb, cmd_len,
> > + transid);
> > else
> > - buf = kvaser_usb_hydra_frame_to_cmd_std(priv, skb, frame_len,
> > - cmd_len, transid);
> > + buf = kvaser_usb_hydra_frame_to_cmd_std(priv, skb, cmd_len,
> > + transid);
> >
> > return buf;
> > }
> > diff --git a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
> > index 14b445643554..47fa7f5a11c6 100644
> > --- a/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
> > +++ b/drivers/net/can/usb/kvaser_usb/kvaser_usb_leaf.c
> > @@ -342,16 +342,14 @@ struct kvaser_usb_err_summary {
> >
> > static void *
> > kvaser_usb_leaf_frame_to_cmd(const struct kvaser_usb_net_priv *priv,
> > - const struct sk_buff *skb, int *frame_len,
> > - int *cmd_len, u16 transid)
> > + const struct sk_buff *skb, int *cmd_len,
> > + u16 transid)
> > {
> > struct kvaser_usb *dev = priv->dev;
> > struct kvaser_cmd *cmd;
> > u8 *cmd_tx_can_flags = NULL; /* GCC */
> > struct can_frame *cf = (struct can_frame *)skb->data;
> >
> > - *frame_len = cf->len;
> > -
> > cmd = kmalloc(sizeof(*cmd), GFP_ATOMIC);
> > if (cmd) {
> > cmd->u.tx_can.tid = transid & 0xff;
> > @@ -587,12 +585,11 @@ static void kvaser_usb_leaf_tx_acknowledge(const struct kvaser_usb *dev,
> > priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > }
> >
> > - stats->tx_packets++;
> > - stats->tx_bytes += context->dlc;
> > -
> > spin_lock_irqsave(&priv->tx_contexts_lock, flags);
> >
> > - can_get_echo_skb(priv->netdev, context->echo_index, NULL);
> > + stats->tx_packets++;
> > + stats->tx_bytes += 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);
[...]
Yours sincerely,
Vincent Mailhol
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