srcu: Move ->lock initialization after srcu_usage allocation

Currently, both __init_srcu_struct() in CONFIG_DEBUG_LOCK_ALLOC=y kernels
and init_srcu_struct() in CONFIG_DEBUG_LOCK_ALLOC=n kernel initialize
the srcu_struct structure's ->lock before the srcu_usage structure has
been allocated.  This of course prevents the ->lock from being moved
to the srcu_usage structure, so this commit moves the initialization
into the init_srcu_struct_fields() after the srcu_usage structure has
been allocated.

Cc: Christoph Hellwig <hch@lst.de>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 1814f3bfc219d1862c076a39fd54a0e4713693e0..c2a024a60f1aab29bb32b21b434b8f722b9d8fc2 100644 (file)
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -240,6 +240,8 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
                ssp->srcu_sup = kzalloc(sizeof(*ssp->srcu_sup), GFP_KERNEL);
        if (!ssp->srcu_sup)
                return -ENOMEM;
+       if (!is_static)
+               spin_lock_init(&ACCESS_PRIVATE(ssp, lock));
        ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
        ssp->srcu_sup->node = NULL;
        mutex_init(&ssp->srcu_sup->srcu_cb_mutex);
@@ -285,7 +287,6 @@ int __init_srcu_struct(struct srcu_struct *ssp, const char *name,
        /* Don't re-initialize a lock while it is held. */
        debug_check_no_locks_freed((void *)ssp, sizeof(*ssp));
        lockdep_init_map(&ssp->dep_map, name, key, 0);
-       spin_lock_init(&ACCESS_PRIVATE(ssp, lock));
        return init_srcu_struct_fields(ssp, false);
 }
 EXPORT_SYMBOL_GPL(__init_srcu_struct);
@@ -302,7 +303,6 @@ EXPORT_SYMBOL_GPL(__init_srcu_struct);
  */
 int init_srcu_struct(struct srcu_struct *ssp)
 {
-       spin_lock_init(&ACCESS_PRIVATE(ssp, lock));
        return init_srcu_struct_fields(ssp, false);
 }
 EXPORT_SYMBOL_GPL(init_srcu_struct);