[PATCH v3 09/30] locking/lockdep: Remove chain_head argument in validate_chain()

Yuyang Du
2019-06-28T09:16:26Z

This argument says whether the chain is a head, meaning having just one
lock, which can actually be tested by lock_chain->depth. So there is no
need to explicitly make this argument, so remove it.

No functional change.

Signed-off-by: Yuyang Du <duyuyang@gmail.com>
---
kernel/locking/lockdep.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4ffb4df..e2ad673 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2807,9 +2807,8 @@ static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
return add_chain_cache(curr, hlock, chain_key);
}

-static int validate_chain(struct task_struct *curr,
- struct held_lock *hlock,
- int chain_head, u64 chain_key)
+static int validate_chain(struct task_struct *curr, struct held_lock *hlock,
+ u64 chain_key)
{
struct lock_chain *chain;
/*
@@ -2857,7 +2856,7 @@ static int validate_chain(struct task_struct *curr,
* Add dependency only if this lock is not the head
* of the chain, and if it's not a secondary read-lock:
*/
- if (!chain_head && ret != 2) {
+ if (chain->depth > 1 && ret != 2) {
if (!check_prevs_add(curr, hlock, chain))
return 0;
}
@@ -2874,7 +2873,7 @@ static int validate_chain(struct task_struct *curr,
#else
static inline int validate_chain(struct task_struct *curr,
struct held_lock *hlock,
- int chain_head, u64 chain_key)
+ u64 chain_key)
{
return 1;
}
@@ -3707,7 +3706,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
struct lock_class *class = NULL;
struct held_lock *hlock;
unsigned int depth;
- int chain_head = 0;
int class_idx;
u64 chain_key;

@@ -3821,14 +3819,12 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
*/
if (DEBUG_LOCKS_WARN_ON(chain_key != INITIAL_CHAIN_KEY))
return 0;
- chain_head = 1;
}

hlock->prev_chain_key = chain_key;
- if (separate_irq_context(curr, hlock)) {
+ if (separate_irq_context(curr, hlock))
chain_key = INITIAL_CHAIN_KEY;
- chain_head = 1;
- }
+
chain_key = iterate_chain_key(chain_key, class_idx);

if (nest_lock && !__lock_is_held(nest_lock, -1)) {
@@ -3841,7 +3837,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
WARN_ON_ONCE(!hlock_class(hlock)->key);
}

- if (!validate_chain(curr, hlock, chain_head, chain_key))
+ if (!validate_chain(curr, hlock, chain_key))
return 0;

curr->curr_chain_key = chain_key;
--
1.8.3.1