diff options
Diffstat (limited to 'lib/smp_processor_id.c')
-rw-r--r-- | lib/smp_processor_id.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c new file mode 100644 index 00000000..4689cb07 --- /dev/null +++ b/lib/smp_processor_id.c @@ -0,0 +1,55 @@ +/* + * lib/smp_processor_id.c + * + * DEBUG_PREEMPT variant of smp_processor_id(). + */ +#include <linux/module.h> +#include <linux/kallsyms.h> +#include <linux/sched.h> + +notrace unsigned int debug_smp_processor_id(void) +{ + unsigned long preempt_count = preempt_count(); + int this_cpu = raw_smp_processor_id(); + + if (likely(preempt_count)) + goto out; + + if (irqs_disabled()) + goto out; + + /* + * Kernel threads bound to a single CPU can safely use + * smp_processor_id(): + */ + if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu))) + goto out; + + /* + * It is valid to assume CPU-locality during early bootup: + */ + if (system_state != SYSTEM_RUNNING) + goto out; + + /* + * Avoid recursion: + */ + preempt_disable_notrace(); + + if (!printk_ratelimit()) + goto out_enable; + + printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] " + "code: %s/%d\n", + preempt_count() - 1, current->comm, current->pid); + print_symbol("caller is %s\n", (long)__builtin_return_address(0)); + dump_stack(); + +out_enable: + preempt_enable_no_resched_notrace(); +out: + return this_cpu; +} + +EXPORT_SYMBOL(debug_smp_processor_id); + |