/* * lib/smp_processor_id.c * * DEBUG_PREEMPT variant of smp_processor_id(). */ #include <linux/module.h> #include <linux/kallsyms.h> #include <linux/sched.h> unsigned int debug_smp_processor_id(void) { unsigned long preempt_count = preempt_count(); int this_cpu = raw_smp_processor_id(); cpumask_t this_mask; if (likely(preempt_count)) goto out; if (irqs_disabled()) goto out; /* * Kernel threads bound to a single CPU can safely use * smp_processor_id(): */ this_mask = cpumask_of_cpu(this_cpu); if (cpus_equal(current->cpus_allowed, this_mask)) goto out; /* * It is valid to assume CPU-locality during early bootup: */ if (system_state != SYSTEM_RUNNING) goto out; /* * Avoid recursion: */ preempt_disable(); if (!printk_ratelimit()) goto out_enable; printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] code: %s/%d\n", preempt_count(), current->comm, current->pid); print_symbol("caller is %s\n", (long)__builtin_return_address(0)); dump_stack(); out_enable: preempt_enable_no_resched(); out: return this_cpu; } EXPORT_SYMBOL(debug_smp_processor_id);