Revert "kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep()"
This reverts commit a69d001cfc
.
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>
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798c75a0d4
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0890147fe0
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@ -22,15 +22,6 @@ DEFINE_MUTEX(kernfs_mutex);
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#define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb)
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static bool kernfs_lockdep(struct kernfs_node *kn)
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{
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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return kn->flags & KERNFS_LOCKDEP;
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#else
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return false;
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#endif
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}
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/**
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* kernfs_name_hash
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* @name: Null terminated string to hash
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@ -147,7 +138,7 @@ struct kernfs_node *kernfs_get_active(struct kernfs_node *kn)
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if (!atomic_inc_unless_negative(&kn->active))
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return NULL;
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if (kernfs_lockdep(kn))
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if (kn->flags & KERNFS_LOCKDEP)
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rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);
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return kn;
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}
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@ -167,7 +158,7 @@ void kernfs_put_active(struct kernfs_node *kn)
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if (unlikely(!kn))
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return;
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if (kernfs_lockdep(kn))
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if (kn->flags & KERNFS_LOCKDEP)
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rwsem_release(&kn->dep_map, 1, _RET_IP_);
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v = atomic_dec_return(&kn->active);
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if (likely(v != KN_DEACTIVATED_BIAS))
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@ -188,22 +179,22 @@ static void kernfs_deactivate(struct kernfs_node *kn)
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BUG_ON(!(kn->flags & KERNFS_REMOVED));
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if (!(kernfs_type(kn) & KERNFS_ACTIVE_REF))
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return;
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rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
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atomic_add(KN_DEACTIVATED_BIAS, &kn->active);
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if (kernfs_lockdep(kn)) {
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rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
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if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS)
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lock_contended(&kn->dep_map, _RET_IP_);
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}
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wait_event(root->deactivate_waitq,
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atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);
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if (kernfs_lockdep(kn)) {
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lock_acquired(&kn->dep_map, _RET_IP_);
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rwsem_release(&kn->dep_map, 1, _RET_IP_);
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}
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}
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/**
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* kernfs_get - get a reference count on a kernfs_node
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@ -34,6 +34,7 @@ enum kernfs_node_type {
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};
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#define KERNFS_TYPE_MASK 0x000f
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#define KERNFS_ACTIVE_REF KERNFS_FILE
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#define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
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enum kernfs_node_flag {
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