1 /* 2 * Provide a default dump_stack() function for architectures 3 * which don't implement their own. 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/export.h> 8 #include <linux/sched.h> 9 #include <linux/smp.h> 10 #include <linux/atomic.h> 11 12 static void __dump_stack(void) 13 { 14 dump_stack_print_info(KERN_DEFAULT); 15 show_stack(NULL, NULL); 16 } 17 18 /** 19 * dump_stack - dump the current task information and its stack trace 20 * 21 * Architectures can override this implementation by implementing its own. 22 */ 23 #ifdef CONFIG_SMP 24 static atomic_t dump_lock = ATOMIC_INIT(-1); 25 26 asmlinkage __visible void dump_stack(void) 27 { 28 int was_locked; 29 int old; 30 int cpu; 31 32 /* 33 * Permit this cpu to perform nested stack dumps while serialising 34 * against other CPUs 35 */ 36 preempt_disable(); 37 38 retry: 39 cpu = smp_processor_id(); 40 old = atomic_cmpxchg(&dump_lock, -1, cpu); 41 if (old == -1) { 42 was_locked = 0; 43 } else if (old == cpu) { 44 was_locked = 1; 45 } else { 46 cpu_relax(); 47 goto retry; 48 } 49 50 __dump_stack(); 51 52 if (!was_locked) 53 atomic_set(&dump_lock, -1); 54 55 preempt_enable(); 56 } 57 #else 58 asmlinkage __visible void dump_stack(void) 59 { 60 __dump_stack(); 61 } 62 #endif 63 EXPORT_SYMBOL(dump_stack); 64