[RFC 3/6] lockdep: LOCKED_ACCESS: Maintain the keys of acqchains

[Boqun Feng]

Add held_lock::prev_acqchain_key and task_struct::curr_acqchain_key to
maintain the keys of acqchains as the same as what lockdep does for
keys of lock classes.

Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
---
 include/linux/lockdep.h  |  3 +++
 include/linux/sched.h    |  3 +++
 kernel/fork.c            |  3 +++
 kernel/locking/lockdep.c | 31 +++++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 140c1c3..2ffe6c3 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -244,6 +244,9 @@ struct held_lock {
 	 * with zero), here we store the previous hash value:
 	 */
 	u64				prev_chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	u64				prev_acqchain_key;
+#endif
 	unsigned long			acquire_ip;
 	struct lockdep_map		*instance;
 	struct lockdep_map		*nest_lock;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a10494a..c24348e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1643,6 +1643,9 @@ struct task_struct {
 	unsigned int lockdep_recursion;
 	struct held_lock held_locks[MAX_LOCK_DEPTH];
 	gfp_t lockdep_reclaim_gfp;
+#ifdef CONFIG_LOCKED_ACCESS
+	u64 curr_acqchain_key;
+#endif
 #endif
 #ifdef CONFIG_UBSAN
 	unsigned int in_ubsan;
diff --git a/kernel/fork.c b/kernel/fork.c
index 2e391c7..d9fc51b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1404,6 +1404,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	p->lockdep_depth = 0; /* no locks held yet */
 	p->curr_chain_key = 0;
 	p->lockdep_recursion = 0;
+# ifdef CONFIG_LOCKED_ACCESS
+	p->curr_acqchain_key = 0;
+# endif
 #endif
 
 #ifdef CONFIG_DEBUG_MUTEXES
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 3aff961..77732a9 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3096,6 +3096,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	int chain_head = 0;
 	int class_idx;
 	u64 chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	u64 acqchain_key;
+#endif
 
 	if (unlikely(!debug_locks))
 		return 0;
@@ -3203,6 +3206,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 		return 0;
 
 	chain_key = curr->curr_chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	acqchain_key = curr->curr_acqchain_key;
+#endif
 	if (!depth) {
 		/*
 		 * How can we have a chain hash when we ain't got no keys?!
@@ -3213,12 +3219,23 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	}
 
 	hlock->prev_chain_key = chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	hlock->prev_acqchain_key = acqchain_key;
+#endif
 	if (separate_irq_context(curr, hlock)) {
 		chain_key = 0;
+
+#ifdef CONFIG_LOCKED_ACCESS
+		acqchain_key = 0;
+#endif
+
 		chain_head = 1;
 	}
 	chain_key = iterate_chain_key(chain_key, id);
 
+#ifdef CONFIG_LOCKED_ACCESS
+	acqchain_key = iterate_acqchain_key(acqchain_key, ip);
+#endif
 	if (nest_lock && !__lock_is_held(nest_lock))
 		return print_lock_nested_lock_not_held(curr, hlock, ip);
 
@@ -3226,6 +3243,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 		return 0;
 
 	curr->curr_chain_key = chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	curr->curr_acqchain_key = acqchain_key;
+#endif
 	curr->lockdep_depth++;
 	check_chain_key(curr);
 #ifdef CONFIG_DEBUG_LOCKDEP
@@ -3355,6 +3375,9 @@ found_it:
 
 	curr->lockdep_depth = i;
 	curr->curr_chain_key = hlock->prev_chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	curr->curr_acqchain_key = hlock->prev_acqchain_key;
+#endif
 
 	for (; i < depth; i++) {
 		hlock = curr->held_locks + i;
@@ -3445,6 +3468,9 @@ found_it:
 
 	curr->lockdep_depth = i;
 	curr->curr_chain_key = hlock->prev_chain_key;
+#ifdef CONFIG_LOCKED_ACCESS
+	curr->curr_acqchain_key = hlock->prev_acqchain_key;
+#endif
 
 	for (i++; i < depth; i++) {
 		hlock = curr->held_locks + i;
@@ -3886,6 +3912,11 @@ void lockdep_reset(void)
 
 	raw_local_irq_save(flags);
 	current->curr_chain_key = 0;
+
+#ifdef CONFIG_LOCKED_ACCESS
+	current->curr_acqchain_key = 0;
+#endif
+
 	current->lockdep_depth = 0;
 	current->lockdep_recursion = 0;
 	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
-- 
2.7.0