On Tue, 12 Jan 2021 17:46:25 -0800 Jakub Kicinski wrote: > On Tue, 12 Jan 2021 11:03:00 +0100 Marc Kleine-Budde wrote: > > On 1/12/21 10:54 AM, Vincent Mailhol wrote: > > > 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@xxxxxxxxxxxxxxxxxx/ > > > > > > Signed-off-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx> > > > > Applied to linux-can-next/testing > > Please make sure to address the warnings before this hits net-next: > > https://patchwork.kernel.org/project/netdevbpf/patch/20210112130538.14912-2-mailhol.vincent@xxxxxxxxxx/ > > Actually it appears not to build with allmodconfig..? Erm, apologies, I confused different CAN patches, this one did not get build tested.
