1 /* 2 * lib/smp_processor_id.c 3 * 4 * DEBUG_PREEMPT variant of smp_processor_id(). 5 */ 6 #include <linux/module.h> 7 #include <linux/kallsyms.h> 8 #include <linux/sched.h> 9 debug_smp_processor_id(void)10notrace unsigned int debug_smp_processor_id(void) 11 { 12 unsigned long preempt_count = preempt_count(); 13 int this_cpu = raw_smp_processor_id(); 14 15 if (likely(preempt_count)) 16 goto out; 17 18 if (irqs_disabled()) 19 goto out; 20 21 /* 22 * Kernel threads bound to a single CPU can safely use 23 * smp_processor_id(): 24 */ 25 if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu))) 26 goto out; 27 28 /* 29 * It is valid to assume CPU-locality during early bootup: 30 */ 31 if (system_state != SYSTEM_RUNNING) 32 goto out; 33 34 /* 35 * Avoid recursion: 36 */ 37 preempt_disable_notrace(); 38 39 if (!printk_ratelimit()) 40 goto out_enable; 41 42 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " 43 "code: %s/%d\n", 44 preempt_count() - 1, current->comm, current->pid); 45 print_symbol("caller is %s\n", (long)__builtin_return_address(0)); 46 dump_stack(); 47 48 out_enable: 49 preempt_enable_no_resched_notrace(); 50 out: 51 return this_cpu; 52 } 53 54 EXPORT_SYMBOL(debug_smp_processor_id); 55 56