<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/net/can/dev/dev.c, branch v6.14</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>Merge tag 'linux-can-next-for-6.14-20250110' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next</title>
<updated>2025-01-11T06:46:08+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2025-01-11T06:46:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7dc8f809b87dd55271ccbbd6043df1490ec5066a'/>
<id>7dc8f809b87dd55271ccbbd6043df1490ec5066a</id>
<content type='text'>
Marc Kleine-Budde says:

====================
pull-request: can-next 2025-01-10

Pierre-Henry Moussay adds PIC64GX compatibility to the DT bindings for
Microchip's mpfs-can IP core.

The next 3 patches are by Sean Nyekjaer and target the tcan4x5x
driver. First the DT bindings is converted to DT schema, then nWKRQ
voltage selection is added to the driver.

Dario Binacchi's patch for the sun4i_can makes the driver more
consistent by adding a likely() to the driver.

Another patch by Sean Nyekjaer for the tcan4x5x driver gets rid of a
false error message.

Charan Pedumuru converts the atmel-can DT bindings to DT schema.

The next 2 patches are by Oliver Hartkopp. The first one maps Oliver's
former mail addresses to a dedicated CAN mail address. The second one
assigns net/sched/em_canid.c additionally to the CAN maintainers.

Ariel Otilibili's patch removes dead code from the CAN dev helper.

The next 3 patches are by Sean Nyekjaer and add HW standby support to
the tcan4x5x driver.

A patch by Dario Binacchi fixes the DT bindings for the st,stm32-bxcan
driver.

The last 4 patches are by Jimmy Assarsson and target the kvaser_usb
and the kvaser_pciefd driver: error statistics are improved and
CAN_CTRLMODE_BERR_REPORTING is added.

* tag 'linux-can-next-for-6.14-20250110' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next:
  can: kvaser_pciefd: Add support for CAN_CTRLMODE_BERR_REPORTING
  can: kvaser_pciefd: Update stats and state even if alloc_can_err_skb() fails
  can: kvaser_usb: Add support for CAN_CTRLMODE_BERR_REPORTING
  can: kvaser_usb: Update stats and state even if alloc_can_err_skb() fails
  dt-bindings: can: st,stm32-bxcan: fix st,gcan property type
  can: m_can: call deinit/init callback when going into suspend/resume
  can: tcan4x5x: add deinit callback to set standby mode
  can: m_can: add deinit callback
  can: dev: can_get_state_str(): Remove dead code
  MAINTAINERS: assign em_canid.c additionally to CAN maintainers
  mailmap: add an entry for Oliver Hartkopp
  dt-bindings: net: can: atmel: Convert to json schema
  can: tcan4x5x: get rid of false clock errors
  can: sun4i_can: continue to use likely() to check skb
  can: tcan4x5x: add option for selecting nWKRQ voltage
  dt-bindings: can: tcan4x5x: Document the ti,nwkrq-voltage-vio option
  dt-bindings: can: convert tcan4x5x.txt to DT schema
  dt-bindings: can: mpfs: add PIC64GX CAN compatibility
====================

Link: https://patch.msgid.link/20250110112712.3214173-1-mkl@pengutronix.de
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Marc Kleine-Budde says:

====================
pull-request: can-next 2025-01-10

Pierre-Henry Moussay adds PIC64GX compatibility to the DT bindings for
Microchip's mpfs-can IP core.

The next 3 patches are by Sean Nyekjaer and target the tcan4x5x
driver. First the DT bindings is converted to DT schema, then nWKRQ
voltage selection is added to the driver.

Dario Binacchi's patch for the sun4i_can makes the driver more
consistent by adding a likely() to the driver.

Another patch by Sean Nyekjaer for the tcan4x5x driver gets rid of a
false error message.

Charan Pedumuru converts the atmel-can DT bindings to DT schema.

The next 2 patches are by Oliver Hartkopp. The first one maps Oliver's
former mail addresses to a dedicated CAN mail address. The second one
assigns net/sched/em_canid.c additionally to the CAN maintainers.

Ariel Otilibili's patch removes dead code from the CAN dev helper.

The next 3 patches are by Sean Nyekjaer and add HW standby support to
the tcan4x5x driver.

A patch by Dario Binacchi fixes the DT bindings for the st,stm32-bxcan
driver.

The last 4 patches are by Jimmy Assarsson and target the kvaser_usb
and the kvaser_pciefd driver: error statistics are improved and
CAN_CTRLMODE_BERR_REPORTING is added.

* tag 'linux-can-next-for-6.14-20250110' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next:
  can: kvaser_pciefd: Add support for CAN_CTRLMODE_BERR_REPORTING
  can: kvaser_pciefd: Update stats and state even if alloc_can_err_skb() fails
  can: kvaser_usb: Add support for CAN_CTRLMODE_BERR_REPORTING
  can: kvaser_usb: Update stats and state even if alloc_can_err_skb() fails
  dt-bindings: can: st,stm32-bxcan: fix st,gcan property type
  can: m_can: call deinit/init callback when going into suspend/resume
  can: tcan4x5x: add deinit callback to set standby mode
  can: m_can: add deinit callback
  can: dev: can_get_state_str(): Remove dead code
  MAINTAINERS: assign em_canid.c additionally to CAN maintainers
  mailmap: add an entry for Oliver Hartkopp
  dt-bindings: net: can: atmel: Convert to json schema
  can: tcan4x5x: get rid of false clock errors
  can: sun4i_can: continue to use likely() to check skb
  can: tcan4x5x: add option for selecting nWKRQ voltage
  dt-bindings: can: tcan4x5x: Document the ti,nwkrq-voltage-vio option
  dt-bindings: can: convert tcan4x5x.txt to DT schema
  dt-bindings: can: mpfs: add PIC64GX CAN compatibility
====================

Link: https://patch.msgid.link/20250110112712.3214173-1-mkl@pengutronix.de
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: can_get_state_str(): Remove dead code</title>
<updated>2024-12-23T11:39:13+00:00</updated>
<author>
<name>Ariel Otilibili</name>
<email>ariel.otilibili-anieli@eurecom.fr</email>
</author>
<published>2024-12-21T11:06:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d50c837675a95f733e53a5e21eb168f8c9f5a73d'/>
<id>d50c837675a95f733e53a5e21eb168f8c9f5a73d</id>
<content type='text'>
The default switch case ends with a return; meaning this return is
never reached.

Coverity-ID: 1497123
Signed-off-by: Ariel Otilibili &lt;ariel.otilibili-anieli@eurecom.fr&gt;
Link: https://patch.msgid.link/20241221111454.1074285-4-ariel.otilibili-anieli@eurecom.fr
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The default switch case ends with a return; meaning this return is
never reached.

Coverity-ID: 1497123
Signed-off-by: Ariel Otilibili &lt;ariel.otilibili-anieli@eurecom.fr&gt;
Link: https://patch.msgid.link/20241221111454.1074285-4-ariel.otilibili-anieli@eurecom.fr
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: can_set_termination(): allow sleeping GPIOs</title>
<updated>2024-11-26T09:13:34+00:00</updated>
<author>
<name>Marc Kleine-Budde</name>
<email>mkl@pengutronix.de</email>
</author>
<published>2024-11-21T10:08:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ee1dfbdd8b4b6de85e96ae2059dc9c1bdb6b49b5'/>
<id>ee1dfbdd8b4b6de85e96ae2059dc9c1bdb6b49b5</id>
<content type='text'>
In commit 6e86a1543c37 ("can: dev: provide optional GPIO based
termination support") GPIO based termination support was added.

For no particular reason that patch uses gpiod_set_value() to set the
GPIO. This leads to the following warning, if the systems uses a
sleeping GPIO, i.e. behind an I2C port expander:

| WARNING: CPU: 0 PID: 379 at /drivers/gpio/gpiolib.c:3496 gpiod_set_value+0x50/0x6c
| CPU: 0 UID: 0 PID: 379 Comm: ip Not tainted 6.11.0-20241016-1 #1 823affae360cc91126e4d316d7a614a8bf86236c

Replace gpiod_set_value() by gpiod_set_value_cansleep() to allow the
use of sleeping GPIOs.

Cc: Nicolai Buchwitz &lt;nb@tipi-net.de&gt;
Cc: Lino Sanfilippo &lt;l.sanfilippo@kunbus.com&gt;
Cc: stable@vger.kernel.org
Reported-by: Leonard Göhrs &lt;l.goehrs@pengutronix.de&gt;
Tested-by: Leonard Göhrs &lt;l.goehrs@pengutronix.de&gt;
Fixes: 6e86a1543c37 ("can: dev: provide optional GPIO based termination support")
Link: https://patch.msgid.link/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In commit 6e86a1543c37 ("can: dev: provide optional GPIO based
termination support") GPIO based termination support was added.

For no particular reason that patch uses gpiod_set_value() to set the
GPIO. This leads to the following warning, if the systems uses a
sleeping GPIO, i.e. behind an I2C port expander:

| WARNING: CPU: 0 PID: 379 at /drivers/gpio/gpiolib.c:3496 gpiod_set_value+0x50/0x6c
| CPU: 0 UID: 0 PID: 379 Comm: ip Not tainted 6.11.0-20241016-1 #1 823affae360cc91126e4d316d7a614a8bf86236c

Replace gpiod_set_value() by gpiod_set_value_cansleep() to allow the
use of sleeping GPIOs.

Cc: Nicolai Buchwitz &lt;nb@tipi-net.de&gt;
Cc: Lino Sanfilippo &lt;l.sanfilippo@kunbus.com&gt;
Cc: stable@vger.kernel.org
Reported-by: Leonard Göhrs &lt;l.goehrs@pengutronix.de&gt;
Tested-by: Leonard Göhrs &lt;l.goehrs@pengutronix.de&gt;
Fixes: 6e86a1543c37 ("can: dev: provide optional GPIO based termination support")
Link: https://patch.msgid.link/20241121-dev-fix-can_set_termination-v1-1-41fa6e29216d@pengutronix.de
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: Remove setting of RX software timestamp</title>
<updated>2024-09-03T22:17:47+00:00</updated>
<author>
<name>Gal Pressman</name>
<email>gal@nvidia.com</email>
</author>
<published>2024-09-01T11:27:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b5ed017a5658892ce99dc68413b506d175401528'/>
<id>b5ed017a5658892ce99dc68413b506d175401528</id>
<content type='text'>
The responsibility for reporting of RX software timestamp has moved to
the core layer (see __ethtool_get_ts_info()), remove usage from the
device drivers.

Reviewed-by: Carolina Jubran &lt;cjubran@nvidia.com&gt;
Reviewed-by: Rahul Rameshbabu &lt;rrameshbabu@nvidia.com&gt;
Signed-off-by: Gal Pressman &lt;gal@nvidia.com&gt;
Reviewed-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
Link: https://patch.msgid.link/20240901112803.212753-3-gal@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The responsibility for reporting of RX software timestamp has moved to
the core layer (see __ethtool_get_ts_info()), remove usage from the
device drivers.

Reviewed-by: Carolina Jubran &lt;cjubran@nvidia.com&gt;
Reviewed-by: Rahul Rameshbabu &lt;rrameshbabu@nvidia.com&gt;
Signed-off-by: Gal Pressman &lt;gal@nvidia.com&gt;
Reviewed-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
Link: https://patch.msgid.link/20240901112803.212753-3-gal@nvidia.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: Add struct kernel_ethtool_ts_info</title>
<updated>2024-07-15T15:02:26+00:00</updated>
<author>
<name>Kory Maincent</name>
<email>kory.maincent@bootlin.com</email>
</author>
<published>2024-07-09T13:53:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2111375b85ad173d58e7b8604246a3de60950ac8'/>
<id>2111375b85ad173d58e7b8604246a3de60950ac8</id>
<content type='text'>
In prevision to add new UAPI for hwtstamp we will be limited to the struct
ethtool_ts_info that is currently passed in fixed binary format through the
ETHTOOL_GET_TS_INFO ethtool ioctl. It would be good if new kernel code
already started operating on an extensible kernel variant of that
structure, similar in concept to struct kernel_hwtstamp_config vs struct
hwtstamp_config.

Since struct ethtool_ts_info is in include/uapi/linux/ethtool.h, here
we introduce the kernel-only structure in include/linux/ethtool.h.
The manual copy is then made in the function called by ETHTOOL_GET_TS_INFO.

Acked-by: Shannon Nelson &lt;shannon.nelson@amd.com&gt;
Acked-by: Alexandra Winter &lt;wintera@linux.ibm.com&gt;
Signed-off-by: Kory Maincent &lt;kory.maincent@bootlin.com&gt;
Link: https://patch.msgid.link/20240709-feature_ptp_netnext-v17-6-b5317f50df2a@bootlin.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In prevision to add new UAPI for hwtstamp we will be limited to the struct
ethtool_ts_info that is currently passed in fixed binary format through the
ETHTOOL_GET_TS_INFO ethtool ioctl. It would be good if new kernel code
already started operating on an extensible kernel variant of that
structure, similar in concept to struct kernel_hwtstamp_config vs struct
hwtstamp_config.

Since struct ethtool_ts_info is in include/uapi/linux/ethtool.h, here
we introduce the kernel-only structure in include/linux/ethtool.h.
The manual copy is then made in the function called by ETHTOOL_GET_TS_INFO.

Acked-by: Shannon Nelson &lt;shannon.nelson@amd.com&gt;
Acked-by: Alexandra Winter &lt;wintera@linux.ibm.com&gt;
Signed-off-by: Kory Maincent &lt;kory.maincent@bootlin.com&gt;
Link: https://patch.msgid.link/20240709-feature_ptp_netnext-v17-6-b5317f50df2a@bootlin.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>net: annotate writes on dev-&gt;mtu from ndo_change_mtu()</title>
<updated>2024-05-07T23:19:14+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2024-05-06T10:28:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1eb2cded45b35816085c1f962933c187d970f9dc'/>
<id>1eb2cded45b35816085c1f962933c187d970f9dc</id>
<content type='text'>
Simon reported that ndo_change_mtu() methods were never
updated to use WRITE_ONCE(dev-&gt;mtu, new_mtu) as hinted
in commit 501a90c94510 ("inet: protect against too small
mtu values.")

We read dev-&gt;mtu without holding RTNL in many places,
with READ_ONCE() annotations.

It is time to take care of ndo_change_mtu() methods
to use corresponding WRITE_ONCE()

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: Simon Horman &lt;horms@kernel.org&gt;
Closes: https://lore.kernel.org/netdev/20240505144608.GB67882@kernel.org/
Reviewed-by: Jacob Keller &lt;jacob.e.keller@intel.com&gt;
Reviewed-by: Sabrina Dubroca &lt;sd@queasysnail.net&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Acked-by: Shannon Nelson &lt;shannon.nelson@amd.com&gt;
Link: https://lore.kernel.org/r/20240506102812.3025432-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Simon reported that ndo_change_mtu() methods were never
updated to use WRITE_ONCE(dev-&gt;mtu, new_mtu) as hinted
in commit 501a90c94510 ("inet: protect against too small
mtu values.")

We read dev-&gt;mtu without holding RTNL in many places,
with READ_ONCE() annotations.

It is time to take care of ndo_change_mtu() methods
to use corresponding WRITE_ONCE()

Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: Simon Horman &lt;horms@kernel.org&gt;
Closes: https://lore.kernel.org/netdev/20240505144608.GB67882@kernel.org/
Reviewed-by: Jacob Keller &lt;jacob.e.keller@intel.com&gt;
Reviewed-by: Sabrina Dubroca &lt;sd@queasysnail.net&gt;
Reviewed-by: Simon Horman &lt;horms@kernel.org&gt;
Acked-by: Shannon Nelson &lt;shannon.nelson@amd.com&gt;
Link: https://lore.kernel.org/r/20240506102812.3025432-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: add can_state_get_by_berr_counter() to return the CAN state based on the current error counters</title>
<updated>2023-10-05T19:44:48+00:00</updated>
<author>
<name>Marc Kleine-Budde</name>
<email>mkl@pengutronix.de</email>
</author>
<published>2023-09-28T07:24:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9beebc2b5d0038a65977a7a14909598c64ce070f'/>
<id>9beebc2b5d0038a65977a7a14909598c64ce070f</id>
<content type='text'>
Some CAN controllers do not have a register that contains the current
CAN state, but only a register that contains the error counters.

Introduce a new function can_state_get_by_berr_counter() that returns
the current TX and RX state depending on the provided CAN bit error
counters.

Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-1-9987d53600e0@pengutronix.de
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Some CAN controllers do not have a register that contains the current
CAN state, but only a register that contains the error counters.

Introduce a new function can_state_get_by_berr_counter() that returns
the current TX and RX state depending on the provided CAN bit error
counters.

Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-1-9987d53600e0@pengutronix.de
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: can_restart(): move debug message and stats after successful restart</title>
<updated>2023-10-05T19:33:41+00:00</updated>
<author>
<name>Marc Kleine-Budde</name>
<email>mkl@pengutronix.de</email>
</author>
<published>2023-09-29T08:18:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f0e0c809c0be05fe865b9ac128ef3ee35c276021'/>
<id>f0e0c809c0be05fe865b9ac128ef3ee35c276021</id>
<content type='text'>
Move the debug message "restarted" and the CAN restart stats_after_
the successful restart of the CAN device, because the restart may
fail.

While there update the error message from printing the error number to
printing symbolic error names.

Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-4-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol &lt;mailhol.vincent@wanadoo.fr&gt;
[mkl: mention stats in subject and description, too]
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Move the debug message "restarted" and the CAN restart stats_after_
the successful restart of the CAN device, because the restart may
fail.

While there update the error message from printing the error number to
printing symbolic error names.

Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-4-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol &lt;mailhol.vincent@wanadoo.fr&gt;
[mkl: mention stats in subject and description, too]
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: can_restart(): reverse logic to remove need for goto</title>
<updated>2023-10-05T19:32:45+00:00</updated>
<author>
<name>Marc Kleine-Budde</name>
<email>mkl@pengutronix.de</email>
</author>
<published>2023-09-29T07:47:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8f3ec204d340af183fb2bb21b8e797ac2ed012b2'/>
<id>8f3ec204d340af183fb2bb21b8e797ac2ed012b2</id>
<content type='text'>
Reverse the logic in the if statement and eliminate the need for a
goto to simplify code readability.

Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-3-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol &lt;mailhol.vincent@wanadoo.fr&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Reverse the logic in the if statement and eliminate the need for a
goto to simplify code readability.

Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-3-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol &lt;mailhol.vincent@wanadoo.fr&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>can: dev: can_restart(): fix race condition between controller restart and netif_carrier_on()</title>
<updated>2023-10-05T19:32:26+00:00</updated>
<author>
<name>Marc Kleine-Budde</name>
<email>mkl@pengutronix.de</email>
</author>
<published>2023-09-29T08:25:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6841cab8c4504835e4011689cbdb3351dec693fd'/>
<id>6841cab8c4504835e4011689cbdb3351dec693fd</id>
<content type='text'>
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-&gt;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 &lt;mailhol.vincent@wanadoo.fr&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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-&gt;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 &lt;mailhol.vincent@wanadoo.fr&gt;
Signed-off-by: Marc Kleine-Budde &lt;mkl@pengutronix.de&gt;
</pre>
</div>
</content>
</entry>
</feed>
