[MTD] [NAND] atmel_nand speedup via {read,write}s{b,w}()
[linux-ginger.git] / lib / smp_processor_id.c
blob6c90fb90e19c2ec25571947b7b98f88262e23ba4
1 /*
2 * lib/smp_processor_id.c
4 * DEBUG_PREEMPT variant of smp_processor_id().
5 */
6 #include <linux/module.h>
7 #include <linux/kallsyms.h>
8 #include <linux/sched.h>
10 unsigned int debug_smp_processor_id(void)
12 unsigned long preempt_count = preempt_count();
13 int this_cpu = raw_smp_processor_id();
14 cpumask_t this_mask;
16 if (likely(preempt_count))
17 goto out;
19 if (irqs_disabled())
20 goto out;
23 * Kernel threads bound to a single CPU can safely use
24 * smp_processor_id():
26 this_mask = cpumask_of_cpu(this_cpu);
28 if (cpus_equal(current->cpus_allowed, this_mask))
29 goto out;
32 * It is valid to assume CPU-locality during early bootup:
34 if (system_state != SYSTEM_RUNNING)
35 goto out;
38 * Avoid recursion:
40 preempt_disable();
42 if (!printk_ratelimit())
43 goto out_enable;
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();
51 out_enable:
52 preempt_enable_no_resched();
53 out:
54 return this_cpu;
57 EXPORT_SYMBOL(debug_smp_processor_id);