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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-13 14:05:13 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-01-13 14:05:13 -0800
commita9f138b0e537de55933335d580ebd38c2bc53c47 (patch)
treef54235f920d392519bde975d42aa4b4534f9561a /fs/kernfs/dir.c
parent8634c422c1b7e50ca8e346f65afc140d93a3212c (diff)
Revert "kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers"
This reverts commit 1ae06819c77cff1ea2833c94f8c093fe8a5c79db. 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> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/kernfs/dir.c')
-rw-r--r--fs/kernfs/dir.c72
1 files changed, 0 insertions, 72 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index a8028be6cdb7..1aeb57969bff 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -986,78 +986,6 @@ void kernfs_remove(struct kernfs_node *kn)
}
/**
- * kernfs_remove_self - remove a kernfs_node from its own method
- * @kn: the self kernfs_node to remove
- *
- * The caller must be running off of a kernfs operation which is invoked
- * with an active reference - e.g. one of kernfs_ops. This can be used to
- * implement a file operation which deletes itself.
- *
- * For example, the "delete" file for a sysfs device directory can be
- * implemented by invoking kernfs_remove_self() on the "delete" file
- * itself. This function breaks the circular dependency of trying to
- * deactivate self while holding an active ref itself. It isn't necessary
- * to modify the usual removal path to use kernfs_remove_self(). The
- * "delete" implementation can simply invoke kernfs_remove_self() on self
- * before proceeding with the usual removal path. kernfs will ignore later
- * kernfs_remove() on self.
- *
- * kernfs_remove_self() can be called multiple times concurrently on the
- * same kernfs_node. Only the first one actually performs removal and
- * returns %true. All others will wait until the kernfs operation which
- * won self-removal finishes and return %false. Note that the losers wait
- * for the completion of not only the winning kernfs_remove_self() but also
- * the whole kernfs_ops which won the arbitration. This can be used to
- * guarantee, for example, all concurrent writes to a "delete" file to
- * finish only after the whole operation is complete.
- */
-bool kernfs_remove_self(struct kernfs_node *kn)
-{
- bool ret;
-
- mutex_lock(&kernfs_mutex);
- __kernfs_deactivate_self(kn);
-
- /*
- * SUICIDAL is used to arbitrate among competing invocations. Only
- * the first one will actually perform removal. When the removal
- * is complete, SUICIDED is set and the active ref is restored
- * while holding kernfs_mutex. The ones which lost arbitration
- * waits for SUICDED && drained which can happen only after the
- * enclosing kernfs operation which executed the winning instance
- * of kernfs_remove_self() finished.
- */
- if (!(kn->flags & KERNFS_SUICIDAL)) {
- kn->flags |= KERNFS_SUICIDAL;
- __kernfs_remove(kn);
- kn->flags |= KERNFS_SUICIDED;
- ret = true;
- } else {
- wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq;
- DEFINE_WAIT(wait);
-
- while (true) {
- prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE);
-
- if ((kn->flags & KERNFS_SUICIDED) &&
- atomic_read(&kn->active) == KN_DEACTIVATED_BIAS)
- break;
-
- mutex_unlock(&kernfs_mutex);
- schedule();
- mutex_lock(&kernfs_mutex);
- }
- finish_wait(waitq, &wait);
- WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb));
- ret = false;
- }
-
- __kernfs_reactivate_self(kn);
- mutex_unlock(&kernfs_mutex);
- return ret;
-}
-
-/**
* kernfs_remove_by_name_ns - find a kernfs_node by name and remove it
* @parent: parent of the target
* @name: name of the kernfs_node to remove