+static cpumask_t backtrace_mask;
+static DEFINE_RAW_SPINLOCK(backtrace_lock);
+
+/* "in progress" flag of arch_trigger_all_cpu_backtrace */
+static unsigned long backtrace_flag;
+
+void smp_send_all_cpu_backtrace(void)
+{
+ unsigned int this_cpu = smp_processor_id();
+ int i;
+
+ if (test_and_set_bit(0, &backtrace_flag))
+ /*
+ * If there is already a trigger_all_cpu_backtrace() in progress
+ * (backtrace_flag == 1), don't output double cpu dump infos.
+ */
+ return;
+
+ cpumask_copy(&backtrace_mask, cpu_online_mask);
+ cpu_clear(this_cpu, backtrace_mask);
+
+ pr_info("Backtrace for cpu %d (current):\n", this_cpu);
+ dump_stack();
+
+ pr_info("\nsending IPI to all other CPUs:\n");
+ smp_cross_call(&backtrace_mask, IPI_CPU_BACKTRACE);
+
+ /* Wait for up to 10 seconds for all other CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpumask_empty(&backtrace_mask))
+ break;
+ mdelay(1);
+ }
+
+ clear_bit(0, &backtrace_flag);
+ smp_mb__after_clear_bit();
+}
+
+/*
+ * ipi_cpu_backtrace - handle IPI from smp_send_all_cpu_backtrace()
+ */
+static void ipi_cpu_backtrace(unsigned int cpu, struct pt_regs *regs)
+{
+ if (cpu_isset(cpu, backtrace_mask)) {
+ raw_spin_lock(&backtrace_lock);
+ pr_warning("IPI backtrace for cpu %d\n", cpu);
+ show_regs(regs);
+ raw_spin_unlock(&backtrace_lock);
+ cpu_clear(cpu, backtrace_mask);
+ }
+}
+