If we're running a kernel compiled with SMP_ON_UP=y and the
hardware only supports UP operation there isn't any
smp_cross_call function assigned. Unfortunately, we call
smp_cross_call() unconditionally in arch_irq_work_raise() and
crash the kernel on UP devices. Check to make sure we're running
on an SMP device before calling smp_cross_call() here.
Fixes: bf18525fd79 "ARM: 7872/1: Support arch_irq_work_raise() via self IPIs" Reported-by: Olof Johansson <olof@lixom.net> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Tested-by: Olof Johansson <olof@lixom.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>