linux-kernel - [PATCH v3 07/18] locking/lockdep: Use lockdep_init

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Date:   Thu, 21 Mar 2019 15:57:14 +0800
From:   Yuyang Du <duyuyang@...il.com>
To:     peterz@...radead.org, will.deacon@....com, mingo@...nel.org
Cc:     bvanassche@....org, ming.lei@...hat.com,
        linux-kernel@...r.kernel.org, joe@...ches.com,
        Yuyang Du <duyuyang@...il.com>
Subject: [PATCH v3 07/18] locking/lockdep: Use lockdep_init_task for task initiation consistently

Despite that there is a lockdep_init_task() which does nothing, lockdep
initiates tasks by assigning lockdep fields and does so inconsistently. Fix
this by using lockdep_init_task().

Signed-off-by: Yuyang Du <duyuyang@...il.com>
---
 include/linux/lockdep.h  |  7 ++++++-
 init/init_task.c         |  2 ++
 kernel/fork.c            |  3 ---
 kernel/locking/lockdep.c | 11 ++++++++---
 4 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 37706ad..267087e 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -282,6 +282,8 @@ struct held_lock {
 extern asmlinkage void lockdep_sys_exit(void);
 extern void lockdep_set_selftest_task(struct task_struct *task);
 
+extern inline void lockdep_init_task(struct task_struct *task);
+
 extern void lockdep_off(void);
 extern void lockdep_on(void);
 
@@ -406,6 +408,10 @@ static inline void lock_set_subclass(struct lockdep_map *lock,
 
 #else /* !CONFIG_LOCKDEP */
 
+static inline void lockdep_init_task(struct task_struct *task)
+{
+}
+
 static inline void lockdep_off(void)
 {
 }
@@ -498,7 +504,6 @@ enum xhlock_context_t {
 	{ .name = (_name), .key = (void *)(_key), }
 
 static inline void lockdep_invariant_state(bool force) {}
-static inline void lockdep_init_task(struct task_struct *task) {}
 static inline void lockdep_free_task(struct task_struct *task) {}
 
 #ifdef CONFIG_LOCK_STAT
diff --git a/init/init_task.c b/init/init_task.c
index 46dbf54..9460878 100644
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -165,6 +165,8 @@ struct task_struct init_task
 	.softirqs_enabled = 1,
 #endif
 #ifdef CONFIG_LOCKDEP
+	.lockdep_depth = 0, /* no locks held yet */
+	.curr_chain_key = 0,
 	.lockdep_recursion = 0,
 #endif
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
diff --git a/kernel/fork.c b/kernel/fork.c
index 77059b2..c0d2000 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1869,9 +1869,6 @@ static __latent_entropy struct task_struct *copy_process(
 	p->pagefault_disabled = 0;
 
 #ifdef CONFIG_LOCKDEP
-	p->lockdep_depth = 0; /* no locks held yet */
-	p->curr_chain_key = 0;
-	p->lockdep_recursion = 0;
 	lockdep_init_task(p);
 #endif
 
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 05c31d6..ef59651 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -358,6 +358,13 @@ static inline u64 iterate_chain_key(u64 key, u32 idx)
 	return k0 | (u64)k1 << 32;
 }
 
+inline void lockdep_init_task(struct task_struct *task)
+{
+	task->lockdep_depth = 0; /* no locks held yet */
+	task->curr_chain_key = 0;
+	task->lockdep_recursion = 0;
+}
+
 void lockdep_off(void)
 {
 	current->lockdep_recursion++;
@@ -4496,9 +4503,7 @@ void lockdep_reset(void)
 	int i;
 
 	raw_local_irq_save(flags);
-	current->curr_chain_key = 0;
-	current->lockdep_depth = 0;
-	current->lockdep_recursion = 0;
+	lockdep_init_task(current);
 	memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
 	nr_hardirq_chains = 0;
 	nr_softirq_chains = 0;
-- 
1.8.3.1