lockdep debugging: give stacktrace for init_error
When I started adding support for lockdep to 64-bit powerpc, I got a
lockdep_init_error and with this patch was able to pinpoint why and where
to put lockdep_init(). Let's support this generally for others adding
lockdep support to their architecture.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 156fce4..734da57 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -375,6 +375,11 @@
* about it later on, in lockdep_info().
*/
static int lockdep_init_error;
+static unsigned long lockdep_init_trace_data[20];
+static struct stack_trace lockdep_init_trace = {
+ .max_entries = ARRAY_SIZE(lockdep_init_trace_data),
+ .entries = lockdep_init_trace_data,
+};
/*
* Various lockdep statistics:
@@ -662,6 +667,7 @@
if (unlikely(!lockdep_initialized)) {
lockdep_init();
lockdep_init_error = 1;
+ save_stack_trace(&lockdep_init_trace);
}
#endif
@@ -3040,8 +3046,11 @@
sizeof(struct held_lock) * MAX_LOCK_DEPTH);
#ifdef CONFIG_DEBUG_LOCKDEP
- if (lockdep_init_error)
- printk("WARNING: lockdep init error! Arch code didnt call lockdep_init() early enough?\n");
+ if (lockdep_init_error) {
+ printk("WARNING: lockdep init error! Arch code didn't call lockdep_init() early enough?\n");
+ printk("Call stack leading to lockdep invocation was:\n");
+ print_stack_trace(&lockdep_init_trace, 0);
+ }
#endif
}