Arnd Bergmann's patch [1] fixed the build dependency problem introduced by
bugfix commit cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure
by default"). This ended up as commit 6abd4577bccc ("can: fix build
dependency"), but I broke Arnd's fix by removing a dependency that we
thought was superfluous.

[1] https://lore.kernel.org/all/20251204100015.1033688-1-arnd@kernel.org/

Meanwhile the problem was also found by intel's kernel test robot,
complaining about undefined symbols:

| ERROR: modpost: "m_can_class_unregister" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_free_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_allocate_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_get_clocks" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_register" [drivers/net/can/m_can/m_can_platform.ko] undefined!

To fix this problem, add the missing dependency again.

Cc: Vincent Mailhol <mailhol@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512132253.vO9WFDJK-lkp@intel.com/
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/all/7427949a-ea7d-4854-9fe4-e01db7d878c7@app.fastmail.com/
Fixes: 6abd4577bccc ("can: fix build dependency")
Fixes: cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure by default")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index 460a74ae6923..cfaea6178a71 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -17,7 +17,7 @@ menuconfig CAN_DEV
 	  virtual ones. If you own such devices or plan to use the virtual CAN
 	  interfaces to develop applications, say Y here.
 
-if CAN_DEV
+if CAN_DEV && CAN
 
 config CAN_VCAN
 	tristate "Virtual Local CAN Interface (vcan)"

---
base-commit: 885bebac9909994050bbbeed0829c727e42bd1b7
change-id: 20251217-can-fix-dependency-63155d8db12d

Best regards,
--  
Marc Kleine-Budde <mkl@pengutronix.de>

On 17/12/2025 at 10:45, Marc Kleine-Budde wrote:
> Arnd Bergmann's patch [1] fixed the build dependency problem introduced by
> bugfix commit cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure
> by default"). This ended up as commit 6abd4577bccc ("can: fix build
> dependency"), but I broke Arnd's fix by removing a dependency that we
> thought was superfluous.

And my comment subverted you into doing so. I think half of the blame goes to me
here.

> [1] https://lore.kernel.org/all/20251204100015.1033688-1-arnd@kernel.org/
> 
> Meanwhile the problem was also found by intel's kernel test robot,
> complaining about undefined symbols:
> 
> | ERROR: modpost: "m_can_class_unregister" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> | ERROR: modpost: "m_can_class_free_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> | ERROR: modpost: "m_can_class_allocate_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> | ERROR: modpost: "m_can_class_get_clocks" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> | ERROR: modpost: "m_can_class_register" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> 
> To fix this problem, add the missing dependency again.
> 
> Cc: Vincent Mailhol <mailhol@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512132253.vO9WFDJK-lkp@intel.com/
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Closes: https://lore.kernel.org/all/7427949a-ea7d-4854-9fe4-e01db7d878c7@app.fastmail.com/
> Fixes: 6abd4577bccc ("can: fix build dependency")
> Fixes: cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure by default")
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Acked-by: Vincent Mailhol <mailhol@kernel.org>


Yours sincerely,
Vincent Mailhol

On 17.12.2025 23:24:05, Vincent Mailhol wrote:
> On 17/12/2025 at 10:45, Marc Kleine-Budde wrote:
> > Arnd Bergmann's patch [1] fixed the build dependency problem introduced by
> > bugfix commit cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure
> > by default"). This ended up as commit 6abd4577bccc ("can: fix build
> > dependency"), but I broke Arnd's fix by removing a dependency that we
> > thought was superfluous.
>
> And my comment subverted you into doing so. I think half of the blame goes to me
> here.

:)

> > [1] https://lore.kernel.org/all/20251204100015.1033688-1-arnd@kernel.org/
> >
> > Meanwhile the problem was also found by intel's kernel test robot,
> > complaining about undefined symbols:
> >
> > | ERROR: modpost: "m_can_class_unregister" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> > | ERROR: modpost: "m_can_class_free_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> > | ERROR: modpost: "m_can_class_allocate_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> > | ERROR: modpost: "m_can_class_get_clocks" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> > | ERROR: modpost: "m_can_class_register" [drivers/net/can/m_can/m_can_platform.ko] undefined!
> >
> > To fix this problem, add the missing dependency again.
> >
> > Cc: Vincent Mailhol <mailhol@kernel.org>
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202512132253.vO9WFDJK-lkp@intel.com/
> > Reported-by: Arnd Bergmann <arnd@arndb.de>
> > Closes: https://lore.kernel.org/all/7427949a-ea7d-4854-9fe4-e01db7d878c7@app.fastmail.com/
> > Fixes: 6abd4577bccc ("can: fix build dependency")
> > Fixes: cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure by default")
> > Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
>
> Acked-by: Vincent Mailhol <mailhol@kernel.org>

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
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