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 9 unsigned int debug_smp_processor_id(void) 10 { 11 unsigned long preempt_count = preempt_count(); 12 int this_cpu = raw_smp_processor_id(); 13 cpumask_t this_mask; 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 this_mask = cpumask_of_cpu(this_cpu); 26 27 if (cpus_equal(current->cpus_allowed, this_mask)) 28 goto out; 29 30 /* 31 * It is valid to assume CPU-locality during early bootup: 32 */ 33 if (system_state != SYSTEM_RUNNING) 34 goto out; 35 36 /* 37 * Avoid recursion: 38 */ 39 preempt_disable(); 40 41 if (!printk_ratelimit()) 42 goto out_enable; 43 44 printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), 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(); 50 out: 51 return this_cpu; 52 } 53 54 EXPORT_SYMBOL(debug_smp_processor_id); 55 56