kernel/linux.git/drivers/net/can/dev/dev.c, branch v6.1.87

can: dev: can_restart(): fix race condition between controller restart and netif_carrier_on()

2023-11-20T10:51:53+00:00

[ Upstream commit 6841cab8c4504835e4011689cbdb3351dec693fd ] This race condition was discovered while updating the at91_can driver to use can_bus_off(). The following scenario describes how the converted at91_can driver would behave. When a CAN device goes into BUS-OFF state, the driver usually stops/resets the CAN device and calls can_bus_off(). This function sets the netif carrier to off, and (if configured by user space) schedules a delayed work that calls can_restart() to restart the CAN device. The can_restart() function first checks if the carrier is off and triggers an error message if the carrier is OK. Then it calls the driver's do_set_mode() function to restart the device, then it sets the netif carrier to on. There is a race window between these two calls. The at91 CAN controller (observed on the sama5d3, a single core 32 bit ARM CPU) has a hardware limitation. If the device goes into bus-off while sending a CAN frame, there is no way to abort the sending of this frame. After the controller is enabled again, another attempt is made to send it. If the bus is still faulty, the device immediately goes back to the bus-off state. The driver calls can_bus_off(), the netif carrier is switched off and another can_restart is scheduled. This occurs within the race window before the original can_restart() handler marks the netif carrier as OK. This would cause the 2nd can_restart() to be called with an OK netif carrier, resulting in an error message. The flow of the 1st can_restart() looks like this: can_restart() // bail out if netif_carrier is OK netif_carrier_ok(dev) priv->do_set_mode(dev, CAN_MODE_START) // enable CAN controller // sama5d3 restarts sending old message // CAN devices goes into BUS_OFF, triggers IRQ // IRQ handler start at91_irq() at91_irq_err_line() can_bus_off() netif_carrier_off() schedule_delayed_work() // IRQ handler end netif_carrier_on() The 2nd can_restart() will be called with an OK netif carrier and the error message will be printed. To close the race window, first set the netif carrier to on, then restart the controller. In case the restart fails with an error code, roll back the netif carrier to off. Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface") Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-2-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin

can: dev: can_restart(): don't crash kernel if carrier is OK

2023-11-20T10:51:53+00:00

[ Upstream commit fe5c9940dfd8ba0c73672dddb30acd1b7a11d4c7 ] During testing, I triggered a can_restart() with the netif carrier being OK [1]. The BUG_ON, which checks if the carrier is OK, results in a fatal kernel crash. This is neither helpful for debugging nor for a production system. [1] The root cause is a race condition in can_restart() which will be fixed in the next patch. Do not crash the kernel, issue an error message instead, and continue restarting the CAN device anyway. Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface") Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-1-91b5c1fd922c@pengutronix.de Reviewed-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin

can: dev: add generic function can_eth_ioctl_hwts()

2022-07-28T09:44:30+00:00

Tools based on libpcap (such as tcpdump) expect the SIOCSHWTSTAMP ioctl call to be supported. This is also specified in the kernel doc [1]. The purpose of this ioctl is to toggle the hardware timestamps. Currently, CAN devices which support hardware timestamping have those always activated. can_eth_ioctl_hwts() is a dumb function that will always succeed when requested to set tx_type to HWTSTAMP_TX_ON or rx_filter to HWTSTAMP_FILTER_ALL. [1] Kernel doc: Timestamping, section 3.1 "Hardware Timestamping Implementation: Device Drivers" Link: https://docs.kernel.org/networking/timestamping.html#hardware-timestamping-implementation-device-drivers Signed-off-by: Vincent Mailhol Link: https://lore.kernel.org/all/20220727101641.198847-9-mailhol.vincent@wanadoo.fr Signed-off-by: Marc Kleine-Budde

can: dev: add generic function can_ethtool_op_get_ts_info_hwts()

2022-07-28T09:44:30+00:00

Add function can_ethtool_op_get_ts_info_hwts(). This function will be used by CAN devices with hardware TX/RX timestamping support to implement ethtool_ops::get_ts_info. This function does not offer support to activate/deactivate hardware timestamps at device level nor support the filter options (which is currently the case for all CAN devices with hardware timestamping support). The fact that hardware timestamp can not be deactivated at hardware level does not impact the userland. As long as the user do not set SO_TIMESTAMPING using a setsockopt() or ioctl(), the kernel will not emit TX timestamps (RX timestamps will still be reproted as it is the case currently). Drivers which need more fine grained control remains free to implement their own function, but we foresee that the generic function introduced here will be sufficient for the majority. Signed-off-by: Vincent Mailhol Link: https://lore.kernel.org/all/20220727101641.198847-8-mailhol.vincent@wanadoo.fr Signed-off-by: Marc Kleine-Budde

can: Kconfig: turn menu "CAN Device Drivers" into a menuconfig using CAN_DEV

2022-06-11T15:11:01+00:00

In the next patches, the software/virtual drivers (slcan, v(x)can) will depend on drivers/net/can/dev/skb.o. This patch changes the scope of the can-dev module to include the above mentioned drivers. To do so, we reuse the menu "CAN Device Drivers" and turn it into a configmenu using the config symbol CAN_DEV (which we released in previous patch). Also, add a description to this new CAN_DEV menuconfig. The symbol CAN_DEV now only triggers the build of skb.o. For this reasons, all the macros from linux/module.h are deported from drivers/net/can/dev/dev.c to drivers/net/can/dev/skb.c. Finally, drivers/net/can/dev/Makefile is adjusted accordingly. Link: https://lore.kernel.org/all/20220610143009.323579-3-mailhol.vincent@wanadoo.fr Suggested-by: Oliver Hartkopp Signed-off-by: Vincent Mailhol Acked-by: Max Staudt Tested-by: Oliver Hartkopp Signed-off-by: Marc Kleine-Budde

can: can-dev: remove obsolete CAN LED support

2022-05-19T20:15:51+00:00

Since commit 30f3b42147ba6f ("can: mark led trigger as broken") the CAN specific LED support was disabled and marked as BROKEN. As the common LED support with CONFIG_LEDS_TRIGGER_NETDEV should do this work now the code can be removed as preparation for a CAN netdevice Kconfig rework. Link: https://lore.kernel.org/all/20220518154527.29046-1-socketcan@hartkopp.net Suggested-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp [mkl: remove led.h from MAINTAINERS] Signed-off-by: Marc Kleine-Budde

can: Use netif_rx().

2022-03-06T11:05:31+00:00

Since commit baebdf48c3600 ("net: dev: Makes sure netif_rx() can be invoked in any context.") the function netif_rx() can be used in preemptible/thread context as well as in interrupt context. Use netif_rx(). Cc: Marc Kleine-Budde Cc: Oliver Hartkopp Cc: Wolfgang Grandegger Cc: linux-can@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Acked-by: Oliver Hartkopp Acked-by: Marc Kleine-Budde Signed-off-by: David S. Miller

can: dev: replace can_priv::ctrlmode_static by can_get_static_ctrlmode()

2022-01-05T11:09:05+00:00

The statically enabled features of a CAN controller can be retrieved using below formula: | u32 ctrlmode_static = priv->ctrlmode & ~priv->ctrlmode_supported; As such, there is no need to store this information. This patch remove the field ctrlmode_static of struct can_priv and provides, in replacement, the inline function can_get_static_ctrlmode() which returns the same value. Link: https://lore.kernel.org/all/20211213160226.56219-2-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde

can: do not increase rx statistics when generating a CAN rx error message frame

2022-01-05T11:09:05+00:00

The CAN error message frames (i.e. error skb) are an interface specific to socket CAN. The payload of the CAN error message frames does not correspond to any actual data sent on the wire. Only an error flag and a delimiter are transmitted when an error occurs (c.f. ISO 11898-1 section 10.4.4.2 "Error flag"). For this reason, it makes no sense to increment the rx_packets and rx_bytes fields of struct net_device_stats because no actual payload were transmitted on the wire. This patch fixes all the CAN drivers. Link: https://lore.kernel.org/all/20211207121531.42941-2-mailhol.vincent@wanadoo.fr CC: Marc Kleine-Budde CC: Nicolas Ferre CC: Alexandre Belloni CC: Ludovic Desroches CC: Chandrasekar Ramakrishnan CC: Maxime Ripard CC: Chen-Yu Tsai CC: Jernej Skrabec CC: Appana Durga Kedareswara rao CC: Naga Sureshkumar Relli CC: Michal Simek CC: Stephane Grosjean Tested-by: Jimmy Assarsson # kvaser Signed-off-by: Vincent Mailhol Acked-by: Stefan Mätje # esd_usb2 Tested-by: Stefan Mätje # esd_usb2 Signed-off-by: Marc Kleine-Budde

can: dev: provide optional GPIO based termination support

2021-08-19T13:07:03+00:00

For CAN buses to work, a termination resistor has to be present at both ends of the bus. This resistor is usually 120 Ohms, other values may be required for special bus topologies. This patch adds support for a generic GPIO based CAN termination. The resistor value has to be specified via device tree, and it can only be attached to or detached from the bus. By default the termination is not active. Link: https://lore.kernel.org/r/20210818071232.20585-4-o.rempel@pengutronix.de Signed-off-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde