| Message ID | 20210110124132.109326-2-mailhol.vincent@wanadoo.fr (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Add software TX timestamps to the CAN devices | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 6 of 6 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 3486704c8a95..3904e0874543 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -484,6 +484,8 @@ int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev, /* save this skb for tx interrupt echo handling */ priv->echo_skb[idx] = skb; + + skb_tx_timestamp(skb); } else { /* locking problem with netif_stop_queue() ?? */ netdev_err(dev, "%s: BUG! echo_skb %d is occupied!\n", __func__, idx);
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. Remarks: * 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. * The hardware rx timestamp of a local loopback message is the hardware tx timestamp. This means that there are no needs to implement SOF_TIMESTAMPING_TX_HARDWARE for CAN sockets. 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 Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> --- drivers/net/can/dev.c | 2 ++ 1 file changed, 2 insertions(+)