| Message ID | 20210112095437.6488-1-mailhol.vincent@wanadoo.fr |
|---|---|
| Headers | show |
| Series | Add software TX timestamps to the CAN devices | expand |
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@hoboy.vegasvil.org/ > > Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Applied to linux-can-next/testing tnx, Marc
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@hoboy.vegasvil.org/ > > > > Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> > > 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@wanadoo.fr/ Actually it appears not to build with allmodconfig..?
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@hoboy.vegasvil.org/ > > > > > > Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> > > > > 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@wanadoo.fr/ > > Actually it appears not to build with allmodconfig..? Erm, apologies, I confused different CAN patches, this one did not get build tested.
On 1/13/21 2:48 AM, Jakub Kicinski wrote: >> Please make sure to address the warnings before this hits net-next: >> >> https://patchwork.kernel.org/project/netdevbpf/patch/20210112130538.14912-2-mailhol.vincent@wanadoo.fr/ >> >> Actually it appears not to build with allmodconfig..? > > Erm, apologies, I confused different CAN patches, this one did not get > build tested. For the record: The patch that was tested by the kbuild robot and failed to build, failed because the patch didn't include a git base reference [1] and was applied to the wrong tree. Using the correct tree it compiles. regards, Marc [1] The submitter already knows to include that next time. -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |