linux-stable.git/drivers/net/can/dev.c, branch v5.10

can: dev: can_restart(): post buffer from the right context

2020-11-15T17:24:35+00:00

netif_rx() is meant to be called from interrupt contexts. can_restart() may be
called by can_restart_work(), which is called from a worqueue, so it may run in
process context. Use netif_rx_ni() instead.

Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface")
Co-developed-by: Loris Fauster 
Signed-off-by: Loris Fauster 
Signed-off-by: Alejandro Concepcion Rodriguez 
Link: https://lore.kernel.org/r/4e84162b-fb31-3a73-fa9a-9438b4bd5234@acoro.eu
[mkl: use netif_rx_ni() instead of netif_rx_any_context()]
Signed-off-by: Marc Kleine-Budde

can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames

2020-11-03T21:30:12+00:00

The can_get_echo_skb() function returns the number of received bytes to
be used for netdev statistics. In the case of RTR frames we get a valid
(potential non-zero) data length value which has to be passed for further
operations. But on the wire RTR frames have no payload length. Therefore
the value to be used in the statistics has to be zero for RTR frames.

Reported-by: Vincent Mailhol 
Signed-off-by: Oliver Hartkopp 
Link: https://lore.kernel.org/r/20201020064443.80164-1-socketcan@hartkopp.net
Fixes: cf5046b309b3 ("can: dev: let can_get_echo_skb() return dlc of CAN frame")
Signed-off-by: Marc Kleine-Budde

can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context

2020-11-03T21:24:19+00:00

If a driver calls can_get_echo_skb() during a hardware IRQ (which is often, but
not always, the case), the 'WARN_ON(in_irq)' in
net/core/skbuff.c#skb_release_head_state() might be triggered, under network
congestion circumstances, together with the potential risk of a NULL pointer
dereference.

The root cause of this issue is the call to kfree_skb() instead of
dev_kfree_skb_irq() in net/core/dev.c#enqueue_to_backlog().

This patch prevents the skb to be freed within the call to netif_rx() by
incrementing its reference count with skb_get(). The skb is finally freed by
one of the in-irq-context safe functions: dev_consume_skb_any() or
dev_kfree_skb_any(). The "any" version is used because some drivers might call
can_get_echo_skb() in a normal context.

The reason for this issue to occur is that initially, in the core network
stack, loopback skb were not supposed to be received in hardware IRQ context.
The CAN stack is an exeption.

This bug was previously reported back in 2017 in [1] but the proposed patch
never got accepted.

While [1] directly modifies net/core/dev.c, we try to propose here a
smoother modification local to CAN network stack (the assumption
behind is that only CAN devices are affected by this issue).

[1] http://lore.kernel.org/r/57a3ffb6-3309-3ad5-5a34-e93c3fe3614d@cetitec.com

Signed-off-by: Vincent Mailhol 
Link: https://lore.kernel.org/r/20201002154219.4887-2-mailhol.vincent@wanadoo.fr
Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface")
Signed-off-by: Marc Kleine-Budde

can: dev: add a helper function to calculate the duration of one bit

2020-10-07T21:17:45+00:00

Rename macro CAN_CALC_SYNC_SEG to CAN_SYNC_SEG and make it available
through include/linux/can/dev.h

Add an helper function can_bit_time() which returns the duration (in
time quanta) of one CAN bit.

Rationale for this patch: the sync segment and the bit time are two
concepts which are defined in the CAN ISO standard. Device drivers for
CAN might need those.

Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
additional information.

Signed-off-by: Vincent Mailhol 
Link: https://lore.kernel.org/r/20201002154219.4887-6-mailhol.vincent@wanadoo.fr
[mkl: Let can_bit_time() return an unsinged int, make argument const]
Signed-off-by: Marc Kleine-Budde

can: dev: can_bus_off(): print scheduling of restart if activated

2020-09-21T08:13:17+00:00

If a CAN device goes into bus-off and has automatic restart enabled, inform
user that a automatic restart is scheduled after the configured delay.

Link: https://lore.kernel.org/r/20200915223527.1417033-14-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: dev: can_change_state(): print human readable state change messages

2020-09-21T08:13:17+00:00

In order to ease debugging let can_change_state() print the human readable
state change messages. Also print the old and new state.

Link: https://lore.kernel.org/r/20200915223527.1417033-13-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: dev: can_put_echo_skb(): propagate error in case of errors

2020-09-21T08:13:16+00:00

The function can_put_echo_skb() can fail for several reasons. It may
fail due to OOM, but when it fails it's usually due to locking problems
in the driver.

In order to help developing and debugging of new drivers propagate error
value in case of errors.

Link: https://lore.kernel.org/r/20200915223527.1417033-12-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: dev: can_put_echo_skb(): print number of echo_skb that is occupied

2020-09-21T08:13:16+00:00

This patch prints the number of the occupied echo_skb, to ease
implementing and debugging of new drivers.

Link: https://lore.kernel.org/r/20200915223527.1417033-11-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde

can: add missing attribute validation for termination

2020-03-03T21:28:48+00:00

Add missing attribute validation for IFLA_CAN_TERMINATION
to the netlink policy.

Fixes: 12a6075cabc0 ("can: dev: add CAN interface termination API")
Signed-off-by: Jakub Kicinski 
Acked-by: Oliver Hartkopp 
Signed-off-by: David S. Miller

can: dev: can_restart(): remove unused code

2019-11-11T20:57:28+00:00

Value assigned to variable err is overwritten at line
562: err = priv->do_set_mode(dev, CAN_MODE_START); before
it can be used.

Also, notice that this code has been there since 2014.

Addresses-Coverity-ID: 1227031
Signed-off-by: Gustavo A. R. Silva 
Signed-off-by: Marc Kleine-Budde