| Message ID | 20210112095437.6488-2-mailhol.vincent@wanadoo.fr |
|---|---|
| State | New |
| Headers | show |
| Series | Add software TX timestamps to the CAN devices | expand |
diff --git a/drivers/net/can/dev/skb.c b/drivers/net/can/dev/skb.c index 53683d4312f1..6a64fe410987 100644 --- a/drivers/net/can/dev/skb.c +++ b/drivers/net/can/dev/skb.c @@ -65,6 +65,8 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, /* save frame_len to reuse it when transmission is completed */ can_skb_prv(skb)->frame_len = frame_len; + skb_tx_timestamp(skb); + /* save this skb for tx interrupt echo handling */ priv->echo_skb[idx] = skb; } else {
Call skb_tx_timestamp() within can_put_echo_skb() so that a software tx timestamp gets attached on the skb. There two main reasons to include this call in can_put_echo_skb(): * It easily allow to enable the tx timestamp on all devices with just one small change. * According to Documentation/networking/timestamping.rst, the tx timestamps should be generated in the device driver as close as possible, but always prior to passing the packet to the network interface. During the call to can_put_echo_skb(), the skb gets cloned meaning that the driver should not dereference the skb variable anymore after can_put_echo_skb() returns. This makes can_put_echo_skb() the very last place we can use the skb without having to access the echo_skb[] array. Remark: by default, skb_tx_timestamp() does nothing. It needs to be activated by passing the SOF_TIMESTAMPING_TX_SOFTWARE flag either through socket options or control messages. References: * Support for the error queue in CAN RAW sockets (which is needed for tx timestamps) was introduced in: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eb88531bdbfaafb827192d1fc6c5a3fcc4fadd96 * Put the call to skb_tx_timestamp() just before adding it to the array: https://lkml.org/lkml/2021/1/10/54 * About Tx hardware timestamps https://lore.kernel.org/linux-can/20210111171152.GB11715@hoboy.vegasvil.org/ Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> --- drivers/net/can/dev/skb.c | 2 ++ 1 file changed, 2 insertions(+)