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lockdep: Check if nested lock is actually held 

It is considered good form to lock the lock you claim to be nested in.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>

[ removed nest_lock arg to print_lock_nested_lock_not_held in favour
  of hlock->nest_lock, also renamed the lock arg to hlock since its
  a held_lock type ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/5051A9E7.5040501@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Maarten Lankhorst 2012-09-13 11:39:51 +02:00 committed by Ingo Molnar
parent 0bd1189e23
commit d094595078
1 changed files with 39 additions and 0 deletions
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39
kernel/lockdep.c
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@ -2998,6 +2998,42 @@ EXPORT_SYMBOL_GPL(lockdep_init_map);
struct lock_class_key __lockdep_no_validate__;
static int
print_lock_nested_lock_not_held(struct task_struct *curr,
struct held_lock *hlock,
unsigned long ip)
{
if (!debug_locks_off())
return 0;
if (debug_locks_silent)
return 0;
printk("\n");
printk("==================================\n");
printk("[ BUG: Nested lock was not taken ]\n");
print_kernel_ident();
printk("----------------------------------\n");
printk("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
print_lock(hlock);
printk("\nbut this task is not holding:\n");
printk("%s\n", hlock->nest_lock->name);
printk("\nstack backtrace:\n");
dump_stack();
printk("\nother info that might help us debug this:\n");
lockdep_print_held_locks(curr);
printk("\nstack backtrace:\n");
dump_stack();
return 0;
}
static int __lock_is_held(struct lockdep_map *lock);
/*
* This gets called for every mutex_lock*()/spin_lock*() operation.
* We maintain the dependency maps and validate the locking attempt:
@ -3139,6 +3175,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
}
chain_key = iterate_chain_key(chain_key, id);
if (nest_lock && !__lock_is_held(nest_lock))
return print_lock_nested_lock_not_held(curr, hlock, ip);
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
return 0;