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Diffstat (limited to 'kernel/locking/lockdep.c')
-rw-r--r--kernel/locking/lockdep.c35
1 files changed, 29 insertions, 6 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 54b74fabf40c..2facbbd146ec 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3969,13 +3969,18 @@ static int separate_irq_context(struct task_struct *curr,
static int mark_lock(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit)
{
- unsigned int new_mask = 1 << new_bit, ret = 1;
+ unsigned int old_mask, new_mask, ret = 1;
if (new_bit >= LOCK_USAGE_STATES) {
DEBUG_LOCKS_WARN_ON(1);
return 0;
}
+ if (new_bit == LOCK_USED && this->read)
+ new_bit = LOCK_USED_READ;
+
+ new_mask = 1 << new_bit;
+
/*
* If already set then do not dirty the cacheline,
* nor do any checks:
@@ -3988,13 +3993,22 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
/*
* Make sure we didn't race:
*/
- if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
- graph_unlock();
- return 1;
- }
+ if (unlikely(hlock_class(this)->usage_mask & new_mask))
+ goto unlock;
+ old_mask = hlock_class(this)->usage_mask;
hlock_class(this)->usage_mask |= new_mask;
+ /*
+ * Save one usage_traces[] entry and map both LOCK_USED and
+ * LOCK_USED_READ onto the same entry.
+ */
+ if (new_bit == LOCK_USED || new_bit == LOCK_USED_READ) {
+ if (old_mask & (LOCKF_USED | LOCKF_USED_READ))
+ goto unlock;
+ new_bit = LOCK_USED;
+ }
+
if (!(hlock_class(this)->usage_traces[new_bit] = save_trace()))
return 0;
@@ -4008,6 +4022,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
return 0;
}
+unlock:
graph_unlock();
/*
@@ -4942,12 +4957,20 @@ static void verify_lock_unused(struct lockdep_map *lock, struct held_lock *hlock
{
#ifdef CONFIG_PROVE_LOCKING
struct lock_class *class = look_up_lock_class(lock, subclass);
+ unsigned long mask = LOCKF_USED;
/* if it doesn't have a class (yet), it certainly hasn't been used yet */
if (!class)
return;
- if (!(class->usage_mask & LOCK_USED))
+ /*
+ * READ locks only conflict with USED, such that if we only ever use
+ * READ locks, there is no deadlock possible -- RCU.
+ */
+ if (!hlock->read)
+ mask |= LOCKF_USED_READ;
+
+ if (!(class->usage_mask & mask))
return;
hlock->class_idx = class - lock_classes;