[PANIC] Kernel panic after rmmod softdog (2.6.8.1)

[PANIC] Kernel panic after rmmod softdog (2.6.8.1)

[Michael Schierl]

Hi,

today, when testing the software watchdog, I accidentally removed the 
software watchdog kernel module and got a kernel panic.

to reproduce:

- build a kernel (2.6.8.1) with softdog built as module
  (and without the NOWAYOUT option)
- load the softdog module
- write something (not ending with a "V") to /dev/watchdog, e. g.
  echo x >/dev/watchdog
- A message will appear that device was closed, but the watchdog is 
  still active (if you wait a minute now, your box will reboot...)
- remove the softdog module
- wait a minute. you will see a kernel panic.

If there is a need for the actual panic message, I'll take a piece of 
paper and transcribe it (no serial console here...), but i doubt it,
since 
it is quite easy to reproduce...

when you disable the watchdog by
  echo "V" >/dev/watchdog
before removing the module, it will not panic.

Hmm, another thing: according to the documentation in watchdog.txt,
softdog does not honor the special "V" for closing the watchdog,
but actually it does.

Please CC me since I am not on the list,

Michael