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Subject[PATCH v3 7/8] locking/lockdep: Add lockdep_early_init() before any lock is taken
Date
The lockdep_init() function is actually called after __lock_acquire()
has been called. So it is not a good place to do chain buckets
initialization. Fortunately, the check for nr_free_chain_hlocks prevents
those chain buckets from being used prematurely.

Add a lockdep_early_init() function that will be called very early in the
boot process and move chain buckets initialization over there to ensure
that the buckets are initialized before __lock_acquire() is called.

Signed-off-by: Waiman Long <longman@redhat.com>
---
include/linux/lockdep.h | 2 ++
init/main.c | 1 +
kernel/locking/lockdep.c | 5 ++++-
3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index c50d01ef1414..efb1ec28a2cd 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -279,6 +279,7 @@ struct held_lock {
* Initialization, self-test and debugging-output methods:
*/
extern void lockdep_init(void);
+extern void lockdep_early_init(void);
extern void lockdep_reset(void);
extern void lockdep_reset_lock(struct lockdep_map *lock);
extern void lockdep_free_key_range(void *start, unsigned long size);
@@ -432,6 +433,7 @@ static inline void lockdep_set_selftest_task(struct task_struct *task)
# define lock_set_class(l, n, k, s, i) do { } while (0)
# define lock_set_subclass(l, s, i) do { } while (0)
# define lockdep_init() do { } while (0)
+# define lockdep_early_init() do { } while (0)
# define lockdep_init_map(lock, name, key, sub) \
do { (void)(name); (void)(key); } while (0)
# define lockdep_set_class(lock, key) do { (void)(key); } while (0)
diff --git a/init/main.c b/init/main.c
index 2cd736059416..571b83981276 100644
--- a/init/main.c
+++ b/init/main.c
@@ -580,6 +580,7 @@ asmlinkage __visible void __init start_kernel(void)
set_task_stack_end_magic(&init_task);
smp_setup_processor_id();
debug_objects_early_init();
+ lockdep_early_init();

cgroup_init_early();

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index a1d839e522a9..165e2361b25e 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -5382,10 +5382,13 @@ void lockdep_unregister_key(struct lock_class_key *key)
}
EXPORT_SYMBOL_GPL(lockdep_unregister_key);

-void __init lockdep_init(void)
+void __init lockdep_early_init(void)
{
init_chain_block_buckets();
+}

+void __init lockdep_init(void)
+{
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");

printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
--
2.18.1
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