From c71063c9c9dc232d0d51f936f237f7dc5681e8e3 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 19 Jul 2007 01:49:02 -0700 Subject: [PATCH] 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 Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/lockdep.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 156fce4960c..734da579ad1 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -375,6 +375,11 @@ unsigned int max_recursion_depth; * 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 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) if (unlikely(!lockdep_initialized)) { lockdep_init(); lockdep_init_error = 1; + save_stack_trace(&lockdep_init_trace); } #endif @@ -3040,8 +3046,11 @@ void __init lockdep_info(void) 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 }