Re: Kernel Oops with: ip link set can0 type can

[ajneu <ajneu1@gmail.com>]

Oliver Hartkopp <socketcan <at> hartkopp.net> writes:

> 
> 
> On 06/21/2016 11:17 AM, Oliver Hartkopp wrote:
> > On 06/21/2016 10:55 AM, ajneu wrote:
> >> ajneu <ajneu1 <at> gmail.com> writes:
> >>
> >>>
> >>> Hi,
> >>>
> >>> issuing the command
> >>>    sudo ip link set can0 type can
> >>> I get Kernel Oops (NULL pointer dereference)
> 
> > But the OOPS should no occur due to your ip usage anyway 
> > This has to be fixed ...
> 
> Can you please check whether my posted patch fixes your problem?
> 
> http://marc.info/?l=linux-can&m=146650412017263&w=2
> 
> I tested it myself with success.
> 
> Thanks for catching this issue!
> 
> Regards,
> Oliver
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> 


Hi Oliver,

thanks for the patch.

I unloaded the old driver, and loaded yours with the patch as follows:
   lsmod | grep can
   sudo rmmod peak_usb # I had to remove this first, since issuing 
                       #   sudo rmmod vcan 
                       # showed
                       # ERROR: Module can_dev is in use by: peak_usb
   sudo rmmod can_dev
   lsmod | grep can
   sudo insmod drivers/net/can/can-dev.ko
   sudo insmod drivers/net/can/usb/peak_usb/peak_usb.ko



Then I tested the command:
  sudo ip link set can0 type can       ## working!

  sudo ip link add can0 type can       ## working!
   => RTNETLINK answers: File exists

~~>So far so good. Good till here.



Then I tested SOME MORE:
  sudo ip link delete can0   ## also removes /sys/class/net/can0

  sudo ip link add can0 type can       ## hmmmm?
   => RTNETLINK answers: Operation not supported

~~>Is this still ok?



Directly after this I managed to provoke a bug:
 I pulled out the Peak USB Adapter, and the computer computer HANGS!!!!
~~>NOTHINGS WORKS. Absolutely nothing. No mouse. No keyboard.

This bug is therefore:
Calling
   sudo ip link delete can0
while the Peak USB Adapter is still plugged in,
and THEN disconnecting the Peak USB Adapter.


Regards,
ajneu



PS:
Note to self -- how to apply Oliver's patch and unload load can kernel modules

## this is under Debian (stretch)
## (I'm currently using Kernel 4.6)
sudo aptitude install build-essential
sudo aptitude install linux-source
mkdir ~/kernel
cd    ~/kernel
tar xf /usr/src/linux-source-4.6.tar.xz
cd ~/kernel/linux-source*
cp /boot/config-4.6.0-1-amd64                          .config
cp /usr/src/linux-headers-4.6.0-1-amd64/Module.symvers .
make prepare
make modules_prepare
make SUBDIRS=scripts/mod
make SUBDIRS=drivers/net/can modules

## perform patch and then recompile with:

make SUBDIRS=drivers/net/can modules

## Then unload old and insert new driver
## (as already shown at beginning of this message)
lsmod | grep can
sudo rmmod peak_usb # I had to remove this first, since issuing 
                    #   sudo rmmod vcan 
                    # showed
                    # ERROR: Module can_dev is in use by: peak_usb
sudo rmmod can_dev
lsmod | grep can
sudo insmod drivers/net/can/can-dev.ko
sudo insmod drivers/net/can/usb/peak_usb/peak_usb.ko