Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / lib / dump_stack.c

diff --git a/kernel/lib/dump_stack.c b/kernel/lib/dump_stack.c
new file mode 100644 (file)
index 0000000..6745c62
--- /dev/null
+++ b/kernel/lib/dump_stack.c
@@ -0,0 +1,63 @@
+/*
+ * Provide a default dump_stack() function for architectures
+ * which don't implement their own.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/atomic.h>
+
+static void __dump_stack(void)
+{
+       dump_stack_print_info(KERN_DEFAULT);
+       show_stack(NULL, NULL);
+}
+
+/**
+ * dump_stack - dump the current task information and its stack trace
+ *
+ * Architectures can override this implementation by implementing its own.
+ */
+#ifdef CONFIG_SMP
+static atomic_t dump_lock = ATOMIC_INIT(-1);
+
+asmlinkage __visible void dump_stack(void)
+{
+       int was_locked;
+       int old;
+       int cpu;
+
+       /*
+        * Permit this cpu to perform nested stack dumps while serialising
+        * against other CPUs
+        */
+       preempt_disable();
+
+retry:
+       cpu = smp_processor_id();
+       old = atomic_cmpxchg(&dump_lock, -1, cpu);
+       if (old == -1) {
+               was_locked = 0;
+       } else if (old == cpu) {
+               was_locked = 1;
+       } else {
+               cpu_relax();
+               goto retry;
+       }
+
+       __dump_stack();
+
+       if (!was_locked)
+               atomic_set(&dump_lock, -1);
+
+       preempt_enable();
+}
+#else
+asmlinkage __visible void dump_stack(void)
+{
+       __dump_stack();
+}
+#endif
+EXPORT_SYMBOL(dump_stack);