From: Steven Rostedt The lockdep output can be pretty cryptic, having a nice output can save a lot of head scratching. When a simple irq inversion scenario is detected by lockdep (lock A taken in interrupt context but also in thread context without disabling interrupts) we get the following output: other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(lockA); lock(lockA); *** DEADLOCK *** Acked-by: Peter Zijlstra Signed-off-by: Steven Rostedt --- kernel/lockdep.c | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index b531c66..3b1ac92 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -2158,6 +2158,24 @@ static void check_chain_key(struct task_struct *curr) #endif } +static void +print_usage_bug_scenario(struct held_lock *lock) +{ + struct lock_class *class = hlock_class(lock); + + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0\n"); + printk(" ----\n"); + printk(" lock("); + __print_lock_name(class); + printk(");\n"); + printk(" \n"); + printk(" lock("); + __print_lock_name(class); + printk(");\n"); + printk("\n *** DEADLOCK ***\n\n"); +} + static int print_usage_bug(struct task_struct *curr, struct held_lock *this, enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit) @@ -2186,6 +2204,8 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this, print_irqtrace_events(curr); printk("\nother info that might help us debug this:\n"); + print_usage_bug_scenario(this); + lockdep_print_held_locks(curr); printk("\nstack backtrace:\n"); -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/