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

[Yuyang Du]

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 <duyuy...@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