tty: use u8 for flags

This makes all those 'char's an explicit 'u8'. This is part of the
continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_receive_buf().

Note that we do not change signedness as we compile with
-funsigned-char.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: William Hubbs <w.d.hubbs@gmail.com>
Cc: Chris Brannon <chris@the-brannons.com>
Cc: Kirk Reiser <kirk@reisers.ca>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Max Staudt <max@enpas.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Andreas Koensgen <ajk@comnets.uni-bremen.de>
Cc: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-18-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: use u8 for chars

This makes all those 'unsigned char's an explicit 'u8'. This is part of
the continuing unification of chars and flags to be consistent u8.

This approaches tty_port_default_receive_buf(). Flags to be next.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: William Hubbs <w.d.hubbs@gmail.com>
Cc: Chris Brannon <chris@the-brannons.com>
Cc: Kirk Reiser <kirk@reisers.ca>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Max Staudt <max@enpas.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Andreas Koensgen <ajk@comnets.uni-bremen.de>
Cc: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-17-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty: make tty_ldisc_ops::*buf*() hooks operate on size_t

Count passed to tty_ldisc_ops::receive_buf*(), ::lookahead_buf(), and
returned from ::receive_buf2() is expected to be size_t. So set it to
size_t to unify with the rest of the code.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: William Hubbs <w.d.hubbs@gmail.com>
Cc: Chris Brannon <chris@the-brannons.com>
Cc: Kirk Reiser <kirk@reisers.ca>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Max Staudt <max@enpas.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Andreas Koensgen <ajk@comnets.uni-bremen.de>
Cc: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230810091510.13006-16-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

can: slcan: remove casts from tty->disc_data

tty->disc_data is 'void *', so there is no need to cast from that.
Therefore remove the casts and assign the pointer directly.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20230731080244.2698-6-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

can: slcan: fix freed work crash

The LTP test pty03 is causing a crash in slcan:
BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 PID: 348 Comm: kworker/0:3 Not tainted 6.0.8-1-default #1 openSUSE Tumbleweed 9d20364b934f5aab0a9bdf84e8f45cfdfae39dab
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014
Workqueue: 0x0 (events)
RIP: 0010:process_one_work (/home/rich/kernel/linux/kernel/workqueue.c:706 /home/rich/kernel/linux/kernel/workqueue.c:2185)
Code: 49 89 ff 41 56 41 55 41 54 55 53 48 89 f3 48 83 ec 10 48 8b 06 48 8b 6f 48 49 89 c4 45 30 e4 a8 04 b8 00 00 00 00 4c 0f 44 e0 <49> 8b 44 24 08 44 8b a8 00 01 00 00 41 83 e5 20 f6 45 10 04 75 0e
RSP: 0018:ffffaf7b40f47e98 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff9d644e1b8b48 RCX: ffff9d649e439968
RDX: 00000000ffff8455 RSI: ffff9d644e1b8b48 RDI: ffff9d64764aa6c0
RBP: ffff9d649e4335c0 R08: 0000000000000c00 R09: ffff9d64764aa734
R10: 0000000000000007 R11: 0000000000000001 R12: 0000000000000000
R13: ffff9d649e4335e8 R14: ffff9d64490da780 R15: ffff9d64764aa6c0
FS: 0000000000000000(0000) GS:ffff9d649e400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000036424000 CR4: 00000000000006f0
Call Trace:
<TASK>
worker_thread (/home/rich/kernel/linux/kernel/workqueue.c:2436)
kthread (/home/rich/kernel/linux/kernel/kthread.c:376)
ret_from_fork (/home/rich/kernel/linux/arch/x86/entry/entry_64.S:312)

Apparently, the slcan's tx_work is freed while being scheduled. While
slcan_netdev_close() (netdev side) calls flush_work(&sl->tx_work),
slcan_close() (tty side) does not. So when the netdev is never set UP,
but the tty is stuffed with bytes and forced to wakeup write, the work
is scheduled, but never flushed.

So add an additional flush_work() to slcan_close() to be sure the work
is flushed under all circumstances.

The Fixes commit below moved flush_work() from slcan_close() to
slcan_netdev_close(). What was the rationale behind it? Maybe we can
drop the one in slcan_netdev_close()?

I see the same pattern in can327. So it perhaps needs the very same fix.

Fixes: cfcb4465e992 ("can: slcan: remove legacy infrastructure")
Link: https://bugzilla.suse.com/show_bug.cgi?id=1205597
Reported-by: Richard Palethorpe <richard.palethorpe@suse.com>
Tested-by: Petr Vorel <petr.vorel@suse.com>
Cc: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-can@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Cc: Max Staudt <max@enpas.org>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Reviewed-by: Max Staudt <max@enpas.org>
Link: https://lore.kernel.org/all/20221201073426.17328-1-jirislaby@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: dev: fix skb drop check

In commit a6d190f8c767 ("can: skb: drop tx skb if in listen only
mode") the priv->ctrlmode element is read even on virtual CAN
interfaces that do not create the struct can_priv at startup. This
out-of-bounds read may lead to CAN frame drops for virtual CAN
interfaces like vcan and vxcan.

This patch mainly reverts the original commit and adds a new helper
for CAN interface drivers that provide the required information in
struct can_priv.

Fixes: a6d190f8c767 ("can: skb: drop tx skb if in listen only mode")
Reported-by: Dariusz Stojaczyk <Dariusz.Stojaczyk@opensynergy.com>
Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc: Max Staudt <max@enpas.org>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20221102095431.36831-1-socketcan@hartkopp.net
Cc: stable@vger.kernel.org # 6.0.x
[mkl: patch pch_can, too]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: add software tx timestamps

TX timestamps were added to the can_put_echo_skb() function of can_dev
modules in [1]. However, slcan does not rely on that function and as
such does not offer TX timestamping.

Add a call to skb_tx_timestamp() in the slc_xmit() function so that
the module now supports TX software timestamps.

[1] commit 741b91f1b0ea ("can: dev: can_put_echo_skb(): add software
tx timestamps")
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=741b91f1b0ea34f00f6a7d4539b767c409291fcf

CC: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20220727101641.198847-4-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

MAINTAINERS: Add maintainer for the slcan driver

At the suggestion of its author Oliver Hartkopp ([1]), I take over the
maintainer-ship and add myself to the authors of the driver.

[1] https://lore.kernel.org/all/507b5973-d673-4755-3b64-b41cb9a13b6f@hartkopp.net

Suggested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-8-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: add support for listen-only mode

For non-legacy, i.e. ip based configuration, add support for listen-only
mode. If listen-only is requested send a listen-only ("L\r") command
instead of an open ("O\r") command to the adapter.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-7-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: use the generic can_change_mtu()

It is useless to define a custom function that does nothing but always
return the same error code. Better to use the generic can_change_mtu()
function.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-6-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: change every `slc' occurrence in `slcan'

In the driver there are parts of code where the prefix `slc' is used and
others where the prefix `slcan' is used instead. The patch replaces
every occurrence of `slc' with `slcan', except for the netdev functions
where, to avoid compilation conflicts, it was necessary to replace `slc'
with `slcan_netdev'.

The patch does not make any functional changes.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-5-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: remove legacy infrastructure

Taking inspiration from the drivers/net/can/can327.c driver and at the
suggestion of its author Max Staudt, I removed legacy stuff like
`SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
and its maintainability.

The use of slcan_devs is derived from a very old kernel, since slip.c
is about 30 years old, so today's kernel allows us to remove it.

The .hangup() ldisc function, which only called the ldisc .close(), has
been removed since the ldisc layer calls .close() in a good place
anyway.

The old slcanX name has been dropped in order to use the standard canX
interface naming. The ioctl SIOCGIFNAME can be used to query the name of
the created interface. Furthermore, there are several ways to get stable
interfaces names in user space, e.g. udev or systemd-networkd.

The `maxdev' module parameter has also been removed.

CC: Max Staudt <max@enpas.org>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Max Staudt <max@enpas.org>
Link: https://lore.kernel.org/all/20220728070254.267974-4-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: remove useless header inclusions

Include only the necessary headers.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-3-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: use KBUILD_MODNAME and define pr_fmt to replace hardcoded names

The driver uses the string "slcan" to populate
tty_ldisc_ops::name. KBUILD_MODNAME also evaluates to "slcan". Use
KBUILD_MODNAME to get rid on the hardcoded string names.

Similarly, the pr_info() and pr_err() hardcoded the "slcan"
prefix. Define pr_fmt so that the "slcan" prefix gets automatically
added.

CC: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/all/20220728070254.267974-2-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: export slcan_ethtool_ops and remove slcan_set_ethtool_ops()

The function slcan_set_ethtool_ops() does one thing: populate
net_device::ethtool_ops. Instead, it is possible to directly assign
this field and remove one function call and slightly reduce the object
size. To do so, export slcan_ethtool_ops so it becomes visible to
sclan-core.c.

This patch reduces the footprint by 14 bytes:

| $ ./scripts/bloat-o-meter drivers/net/can/slcan/slcan.{old,new}.o
| drivers/net/can/slcan/slcan.o
| add/remove: 0/1 grow/shrink: 1/0 up/down: 15/-29 (-14)
| Function old new delta
| slcan_open 1010 1025 +15
| slcan_set_ethtool_ops 29 - -29
| Total: Before=11115, After=11101, chg -0.13%

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20220727104939.279022-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: add CAN_ERR_CNT flag to notify availability of error counter

Add a dedicated flag in uapi/linux/can/error.h to notify the userland
that fields data[6] and data[7] of the CAN error frame were
respectively populated with the tx and rx error counters.

For all driver tree-wide, set up this flags whenever needed.

Link: https://lore.kernel.org/all/20220719143550.3681-12-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: do not report txerr and rxerr during bus-off

During bus off, the error count is greater than 255 and can not fit in
a u8.

alloc_can_err_skb() already sets cf to NULL if the allocation fails [1],
so the redundant cf = NULL assignment gets removed.

[1] https://elixir.bootlin.com/linux/latest/source/drivers/net/can/dev/skb.c#L187

Fixes: 0a9cdcf098a4 ("can: slcan: extend the protocol with CAN state info")
Link: https://lore.kernel.org/all/20220719143550.3681-5-mailhol.vincent@wanadoo.fr
CC: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: do not sleep with a spin lock held

We can't call close_candev() with a spin lock held, so release the lock
before calling it. After calling close_candev(), we can update the
fields of the private `struct can_priv' without having to acquire the
lock.

Fixes: c4e54b063f42f ("can: slcan: use CAN network device driver API")
Link: https://lore.kernel.org/linux-kernel/Ysrf1Yc5DaRGN1WE@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/all/20220715072951.859586-1-dario.binacchi@amarulasolutions.com
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: clean up if/else

Remove braces after if() for single statement blocks, also remove else
after return() in if() block.

Link: https://lore.kernel.org/all/20220704125954.1587880-6-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: convert comparison to NULL into !val

All comparison to NULL could be written "!val", convert them to make
checkpatch happy.

Link: https://lore.kernel.org/all/20220704125954.1587880-5-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: fix whitespace issues

Add and remove whitespace to make checkpatch happy.

Link: https://lore.kernel.org/all/20220704125954.1587880-4-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: slcan_init() convert printk(LEVEL ...) to pr_level()

Convert the last printk(LEVEL ...) to pr_level().

Link: https://lore.kernel.org/all/20220704125954.1587880-3-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: convert comments to network style comments

Convert all comments to network subsystem style comments.

Link: https://lore.kernel.org/all/20220704125954.1587880-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: use scnprintf() as a hardening measure

The snprintf() function returns the number of bytes which *would* have
been copied if there were no space. So, since this code does not check
the return value, there if the buffer was not large enough then there
would be a buffer overflow two lines later when it does:

actual = sl->tty->ops->write(sl->tty, sl->xbuff, n);

Use scnprintf() instead because that returns the number of bytes which
were actually copied.

Fixes: 52f9ac85b876 ("can: slcan: allow to send commands to the adapter")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/all/YsVA9KoY/ZSvNGYk@kili
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: extend the protocol with CAN state info

It extends the protocol to receive the adapter CAN state changes
(warning, busoff, etc.) and forward them to the netdev upper levels.

Link: https://lore.kernel.org/all/20220628163137.413025-13-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: extend the protocol with error info

It extends the protocol to receive the adapter CAN communication errors
and forward them to the netdev upper levels.

Link: https://lore.kernel.org/all/20220628163137.413025-12-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: add ethtool support to reset adapter errors

This patch adds a private flag to the slcan driver to switch the
"err-rst-on-open" setting on and off.

"err-rst-on-open" on - Reset error states on opening command

"err-rst-on-open" off - Don't reset error states on opening command
(default)

The setting can only be changed if the interface is down:

ip link set dev can0 down
ethtool --set-priv-flags can0 err-rst-on-open {off|on}
ip link set dev can0 up

Link: https://lore.kernel.org/all/20220628163137.413025-11-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

can: slcan: move driver into separate sub directory

This patch moves the slcan driver into a separate directory, a later
patch will add more files.

Link: https://lore.kernel.org/all/20220628163137.413025-10-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>