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Commit f4b3e631 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

Revert "kernfs: make kernfs_get_active() block if the node is deactivated but not removed" 



This reverts commit 895a068a.

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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9b0925a6

fs/kernfs/dir.c

+4 −21
Original line number Original line Diff line number Diff line
@@ -149,25 +149,12 @@ struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) 
	if (unlikely(!kn))

	if (unlikely(!kn))

		return NULL;

		return NULL;





	if (!atomic_inc_unless_negative(&kn->active))

		return NULL;



	if (kernfs_lockdep(kn))

	if (kernfs_lockdep(kn))

		rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);

		rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_);



	/*

	 * Try to obtain an active ref.  If @kn is deactivated, we block

	 * till either it's reactivated or killed.

	 */

	do {

		if (atomic_inc_unless_negative(&kn->active))

	return kn;

	return kn;



		wait_event(kernfs_root(kn)->deactivate_waitq,

			   atomic_read(&kn->active) >= 0 ||

			   RB_EMPTY_NODE(&kn->rb));

	} while (!RB_EMPTY_NODE(&kn->rb));



	if (kernfs_lockdep(kn))

		rwsem_release(&kn->dep_map, 1, _RET_IP_);

	return NULL;

}

}





/**

/**
@@ -799,7 +786,6 @@ static void __kernfs_deactivate(struct kernfs_node *kn) 




static void __kernfs_remove(struct kernfs_node *kn)

static void __kernfs_remove(struct kernfs_node *kn)

{

{

	struct kernfs_root *root = kernfs_root(kn);

	struct kernfs_node *pos;

	struct kernfs_node *pos;





	lockdep_assert_held(&kernfs_mutex);

	lockdep_assert_held(&kernfs_mutex);
@@ -851,9 +837,6 @@ static void __kernfs_remove(struct kernfs_node *kn) 




		kernfs_put(pos);

		kernfs_put(pos);

	} while (pos != kn);

	} while (pos != kn);



	/* some nodes killed, kick get_active waiters */

	wake_up_all(&root->deactivate_waitq);

}

}





/**

/**