A looney tunes server sending an invalid error code (which is !IS_ERR_VALUE)
can result in a client oops. So fix it by adding a check and converting unknown
or invalid error codes to -ESERVERFAULT.
Signed-off-by: Abhishek Kulkarni <adkulkar@umail.iu.edu>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>