Revert "kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep()"
This reverts commit a69d001cfc712b96ec9d7ba44d6285702a38dabf.
Tejun writes:
I'm sorry but can you please revert the whole series?
get_active() waiting while a node is deactivated has potential
to lead to deadlock and that deactivate/reactivate interface is
something fundamentally flawed and that cgroup will have to work
with the remove_self() like everybody else. IOW, I think the
first posting was correct.
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 1c9130a3..ed62de6 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -22,15 +22,6 @@
#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
@@ -147,7 +138,7 @@
if (!atomic_inc_unless_negative(&kn->active))
return NULL;
- if (kernfs_lockdep(kn))
+ if (kn->flags & KERNFS_LOCKDEP)
rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
return kn;
}
@@ -167,7 +158,7 @@
if (unlikely(!kn))
return;
- if (kernfs_lockdep(kn))
+ if (kn->flags & KERNFS_LOCKDEP)
rwsem_release(&kn->dep_map, 1, _RET_IP_);
v = atomic_dec_return(&kn->active);
if (likely(v != KN_DEACTIVATED_BIAS))
@@ -188,21 +179,21 @@
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 (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_);
- }
+ 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);
- if (kernfs_lockdep(kn)) {
- lock_acquired(&kn->dep_map, _RET_IP_);
- rwsem_release(&kn->dep_map, 1, _RET_IP_);
- }
+ lock_acquired(&kn->dep_map, _RET_IP_);
+ rwsem_release(&kn->dep_map, 1, _RET_IP_);
}
/**
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 42ad32f..232f1a6 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -34,6 +34,7 @@
};
#define KERNFS_TYPE_MASK 0x000f
+#define KERNFS_ACTIVE_REF KERNFS_FILE
#define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
enum kernfs_node_flag {