what does smp_cross_call does?

Hi all, Could any one tell me what does smp_cross_call() means? My device (Dual call) encounter a soft lockup here with following info: [ 101.654724:0] PC is at generic_exec_single+0x7c/0x94 [ 101.659698:0] LR is at arch_send_call_function_single_ipi+0x3c/0x48 I check the code, and find the LR is point to smp_cross_call() void arch_send_call_function_single_ipi(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE); } Cheers, Jacky