From: Marc Kleine-Budde <mkl@pengutronix.de>
To: netdev@vger.kernel.org
Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org,
kernel@pengutronix.de,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [net-next 16/17] can: dev: can_put_echo_skb(): add software tx timestamps
Date: Wed, 13 Jan 2021 22:14:09 +0100 [thread overview]
Message-ID: <20210113211410.917108-17-mkl@pengutronix.de> (raw)
In-Reply-To: <20210113211410.917108-1-mkl@pengutronix.de>
From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Call skb_tx_timestamp() within can_put_echo_skb() so that a software tx
timestamp gets attached to 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//torvalds/c/eb88531bdbfaafb827192d1fc6c5a3fcc4fadd96
* Put the call to skb_tx_timestamp() just before adding it to the
array:
https://lore.kernel.org/r/043c3ea1-6bdd-59c0-0269-27b2b5b36cec@victronenergy.com
* About Tx hardware timestamps
https://lore.kernel.org/r/20210111171152.GB11715@hoboy.vegasvil.org
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210112095437.6488-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
drivers/net/can/dev/skb.c | 2 ++
1 file changed, 2 insertions(+)
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 {
--
2.29.2
next prev parent reply other threads:[~2021-01-14 2:16 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 21:13 pull-request: can-next 2021-01-13 Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 01/17] MAINTAINERS: adjust entry to tcan4x5x file split Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 02/17] MAINTAINERS: CAN network layer: add missing header file can-ml.h Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 03/17] can: dev: move driver related infrastructure into separate subdir Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 04/17] can: dev: move bittiming related code into seperate file Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 05/17] can: dev: move length " Marc Kleine-Budde
2021-01-13 21:13 ` [net-next 06/17] can: dev: move skb related " Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 07/17] can: dev: move netlink related code " Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 08/17] can: length: convert to kernel coding style Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 09/17] can: length: can_fd_len2dlc(): simplify length calculcation Marc Kleine-Budde
2021-01-14 1:59 ` Vincent MAILHOL
2021-01-14 7:34 ` Marc Kleine-Budde
2021-01-14 8:23 ` Oliver Hartkopp
2021-01-14 9:16 ` Vincent MAILHOL
2021-01-14 17:03 ` Oliver Hartkopp
2021-01-15 1:57 ` Vincent MAILHOL
2021-01-13 21:14 ` [net-next 10/17] can: length: canfd_sanitize_len(): add function to sanitize CAN-FD data length Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 11/17] can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 12/17] can: dev: extend struct can_skb_priv to hold CAN frame length Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 13/17] can: dev: can_put_echo_skb(): extend to handle frame_len Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 14/17] can: dev: can_get_echo_skb(): extend to return can frame length Marc Kleine-Budde
2021-01-13 21:14 ` [net-next 15/17] can: dev: can_rx_offload_get_echo_skb(): " Marc Kleine-Budde
2021-01-13 21:14 ` Marc Kleine-Budde [this message]
2021-01-13 21:14 ` [net-next 17/17] can: tcan4x5x: remove __packed attribute from struct tcan4x5x_map_buf Marc Kleine-Budde
2021-01-14 7:32 ` pull-request: can-next 2021-01-13 Marc Kleine-Budde
2021-01-14 7:56 pull-request: can-next 2021-01-14 Marc Kleine-Budde
2021-01-14 7:56 ` [net-next 16/17] can: dev: can_put_echo_skb(): add software tx timestamps Marc Kleine-Budde
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