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authorTejun Heo <tj@kernel.org>2014-01-10 17:57:20 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-11 01:44:25 +0400
commita69d001cfc712b96ec9d7ba44d6285702a38dabf (patch)
tree295a4f2c57a883d45596078a28278cb054bf9a02 /fs
parentea1c472dfeada211a0100daa7976e8e8e779b858 (diff)
downloadlinux-a69d001cfc712b96ec9d7ba44d6285702a38dabf.tar.xz
kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep()
There currently are two mechanisms gating active ref lockdep annotations - KERNFS_LOCKDEP flag and KERNFS_ACTIVE_REF type mask. The former disables lockdep annotations in kernfs_get/put_active() while the latter disables all of kernfs_deactivate(). While KERNFS_ACTIVE_REF also behaves as an optimization to skip the deactivation step for non-file nodes, the benefit is marginal and it needlessly diverges code paths. Let's drop KERNFS_ACTIVE_REF and use KERNFS_LOCKDEP in kernfs_deactivate() too. While at it, add a test helper kernfs_lockdep() to test KERNFS_LOCKDEP flag so that it's more convenient and the related code can be compiled out when not enabled. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/kernfs/dir.c31
1 files changed, 20 insertions, 11 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index ed62de6cdf8f..1c9130a33048 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -22,6 +22,15 @@ DEFINE_MUTEX(kernfs_mutex);
#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
+static bool kernfs_lockdep(struct kernfs_node *kn)
+{
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ return kn->flags & KERNFS_LOCKDEP;
+#else
+ return false;
+#endif
+}
+
/**
* kernfs_name_hash
* @name: Null terminated string to hash
@@ -138,7 +147,7 @@ struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
if (!atomic_inc_unless_negative(&kn->active))
return NULL;
- if (kn->flags & KERNFS_LOCKDEP)
+ if (kernfs_lockdep(kn))
rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
return kn;
}
@@ -158,7 +167,7 @@ void kernfs_put_active(struct kernfs_node *kn)
if (unlikely(!kn))
return;
- if (kn->flags & KERNFS_LOCKDEP)
+ if (kernfs_lockdep(kn))
rwsem_release(&kn->dep_map, 1, _RET_IP_);
v = atomic_dec_return(&kn->active);
if (likely(v != KN_DEACTIVATED_BIAS))
@@ -179,21 +188,21 @@ static void kernfs_deactivate(struct kernfs_node *kn)
BUG_ON(!(kn->flags & KERNFS_REMOVED));
- if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF))
- return;
-
- rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
-
atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
- if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
- lock_contended(&kn->dep_map, _RET_IP_);
+ if (kernfs_lockdep(kn)) {
+ rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
+ if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
+ lock_contended(&kn->dep_map, _RET_IP_);
+ }
wait_event(root->deactivate_waitq,
atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
- lock_acquired(&kn->dep_map, _RET_IP_);
- rwsem_release(&kn->dep_map, 1, _RET_IP_);
+ if (kernfs_lockdep(kn)) {
+ lock_acquired(&kn->dep_map, _RET_IP_);
+ rwsem_release(&kn->dep_map, 1, _RET_IP_);
+ }
}
/**