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 10 notrace unsigned int debug_smp_processor_id(void) 11 { 12 unsigned long preempt_count = preempt_count(); 13 int this_cpu = raw_smp_processor_id(); 14 cpumask_of_cpu_ptr_declare(this_mask); 15 16 if (likely(preempt_count)) 17 goto out; 18 19 if (irqs_disabled()) 20 goto out; 21 22 /* 23 * Kernel threads bound to a single CPU can safely use 24 * smp_processor_id(): 25 */ 26 cpumask_of_cpu_ptr_next(this_mask, this_cpu); 27 28 if (cpus_equal(current->cpus_allowed, *this_mask)) 29 goto out; 30 31 /* 32 * It is valid to assume CPU-locality during early bootup: 33 */ 34 if (system_state != SYSTEM_RUNNING) 35 goto out; 36 37 /* 38 * Avoid recursion: 39 */ 40 preempt_disable_notrace(); 41 42 if (!printk_ratelimit()) 43 goto out_enable; 44 45 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " 46 "code: %s/%d\n", 47 preempt_count() - 1, current->comm, current->pid); 48 print_symbol("caller is %s\n", (long)__builtin_return_address(0)); 49 dump_stack(); 50 51 out_enable: 52 preempt_enable_no_resched_notrace(); 53 out: 54 return this_cpu; 55 } 56 57 EXPORT_SYMBOL(debug_smp_processor_id); 58 59