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lockdep: Print a nicer description for simple irq lock inversions 

Lockdep output can be pretty cryptic, having nicer 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 now get the following (hopefully more informative) output:

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(lockA);
  <Interrupt>
    lock(lockA);

 *** DEADLOCK ***

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014300.436140880@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
hifive-unleashed-5.1
Steven Rostedt 2011-04-20 21:41:59 -04:00 committed by Ingo Molnar
parent 6be8c3935b
commit 282b5c2f6f
1 changed files with 20 additions and 0 deletions
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20
kernel/lockdep.c
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@ -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(" <Interrupt>\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");