When the sk_timer function x25_heartbeat_expiry() is called by the
kernel in a running/terminating process, spinlock-recursion and
spinlock-lockup locks up the kernel.  This has happened with testing
on some distro's and the patch below fixed it.
Signed-off-by: NShaun Pereira <spereira@tusc.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>