Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 531 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/admin-state.c b/drivers/md/dm-vdo/admin-state.c
new file mode 100644
index 000000000..da153fef0
--- /dev/null
+++ b/drivers/md/dm-vdo/admin-state.c
@@ -0,0 +1,531 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "admin-state.h"
+
+#include "logger.h"
+#include "memory-alloc.h"
+#include "permassert.h"
+
+#include "completion.h"
+#include "types.h"
+
+static const struct admin_state_code VDO_CODE_NORMAL_OPERATION = {
+	.name = "VDO_ADMIN_STATE_NORMAL_OPERATION",
+	.normal = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_NORMAL_OPERATION = &VDO_CODE_NORMAL_OPERATION;
+static const struct admin_state_code VDO_CODE_OPERATING = {
+	.name = "VDO_ADMIN_STATE_OPERATING",
+	.normal = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_OPERATING = &VDO_CODE_OPERATING;
+static const struct admin_state_code VDO_CODE_FORMATTING = {
+	.name = "VDO_ADMIN_STATE_FORMATTING",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_FORMATTING = &VDO_CODE_FORMATTING;
+static const struct admin_state_code VDO_CODE_PRE_LOADING = {
+	.name = "VDO_ADMIN_STATE_PRE_LOADING",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADING = &VDO_CODE_PRE_LOADING;
+static const struct admin_state_code VDO_CODE_PRE_LOADED = {
+	.name = "VDO_ADMIN_STATE_PRE_LOADED",
+};
+const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADED = &VDO_CODE_PRE_LOADED;
+static const struct admin_state_code VDO_CODE_LOADING = {
+	.name = "VDO_ADMIN_STATE_LOADING",
+	.normal = true,
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING = &VDO_CODE_LOADING;
+static const struct admin_state_code VDO_CODE_LOADING_FOR_RECOVERY = {
+	.name = "VDO_ADMIN_STATE_LOADING_FOR_RECOVERY",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_RECOVERY =
+	&VDO_CODE_LOADING_FOR_RECOVERY;
+static const struct admin_state_code VDO_CODE_LOADING_FOR_REBUILD = {
+	.name = "VDO_ADMIN_STATE_LOADING_FOR_REBUILD",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_REBUILD = &VDO_CODE_LOADING_FOR_REBUILD;
+static const struct admin_state_code VDO_CODE_WAITING_FOR_RECOVERY = {
+	.name = "VDO_ADMIN_STATE_WAITING_FOR_RECOVERY",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_WAITING_FOR_RECOVERY =
+	&VDO_CODE_WAITING_FOR_RECOVERY;
+static const struct admin_state_code VDO_CODE_NEW = {
+	.name = "VDO_ADMIN_STATE_NEW",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_NEW = &VDO_CODE_NEW;
+static const struct admin_state_code VDO_CODE_INITIALIZED = {
+	.name = "VDO_ADMIN_STATE_INITIALIZED",
+};
+const struct admin_state_code *VDO_ADMIN_STATE_INITIALIZED = &VDO_CODE_INITIALIZED;
+static const struct admin_state_code VDO_CODE_RECOVERING = {
+	.name = "VDO_ADMIN_STATE_RECOVERING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_RECOVERING = &VDO_CODE_RECOVERING;
+static const struct admin_state_code VDO_CODE_REBUILDING = {
+	.name = "VDO_ADMIN_STATE_REBUILDING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_REBUILDING = &VDO_CODE_REBUILDING;
+static const struct admin_state_code VDO_CODE_SAVING = {
+	.name = "VDO_ADMIN_STATE_SAVING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVING = &VDO_CODE_SAVING;
+static const struct admin_state_code VDO_CODE_SAVED = {
+	.name = "VDO_ADMIN_STATE_SAVED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVED = &VDO_CODE_SAVED;
+static const struct admin_state_code VDO_CODE_SCRUBBING = {
+	.name = "VDO_ADMIN_STATE_SCRUBBING",
+	.draining = true,
+	.loading = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SCRUBBING = &VDO_CODE_SCRUBBING;
+static const struct admin_state_code VDO_CODE_SAVE_FOR_SCRUBBING = {
+	.name = "VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING = &VDO_CODE_SAVE_FOR_SCRUBBING;
+static const struct admin_state_code VDO_CODE_STOPPING = {
+	.name = "VDO_ADMIN_STATE_STOPPING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_STOPPING = &VDO_CODE_STOPPING;
+static const struct admin_state_code VDO_CODE_STOPPED = {
+	.name = "VDO_ADMIN_STATE_STOPPED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_STOPPED = &VDO_CODE_STOPPED;
+static const struct admin_state_code VDO_CODE_SUSPENDING = {
+	.name = "VDO_ADMIN_STATE_SUSPENDING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDING = &VDO_CODE_SUSPENDING;
+static const struct admin_state_code VDO_CODE_SUSPENDED = {
+	.name = "VDO_ADMIN_STATE_SUSPENDED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED = &VDO_CODE_SUSPENDED;
+static const struct admin_state_code VDO_CODE_SUSPENDED_OPERATION = {
+	.name = "VDO_ADMIN_STATE_SUSPENDED_OPERATION",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED_OPERATION = &VDO_CODE_SUSPENDED_OPERATION;
+static const struct admin_state_code VDO_CODE_RESUMING = {
+	.name = "VDO_ADMIN_STATE_RESUMING",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_RESUMING = &VDO_CODE_RESUMING;
+
+/**
+ * get_next_state() - Determine the state which should be set after a given operation completes
+ *                    based on the operation and the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ *
+ * Return: The state to set when the operation completes or NULL if the operation can not be
+ *         started in the current state.
+ */
+static const struct admin_state_code *get_next_state(const struct admin_state *state,
+						     const struct admin_state_code *operation)
+{
+	const struct admin_state_code *code = vdo_get_admin_state_code(state);
+
+	if (code->operating)
+		return NULL;
+
+	if (operation == VDO_ADMIN_STATE_SAVING)
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_SAVED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_SUSPENDING) {
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION
+			? VDO_ADMIN_STATE_SUSPENDED
+			: NULL);
+	}
+
+	if (operation == VDO_ADMIN_STATE_STOPPING)
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_STOPPED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_PRE_LOADING)
+		return (code == VDO_ADMIN_STATE_INITIALIZED ? VDO_ADMIN_STATE_PRE_LOADED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_SUSPENDED_OPERATION) {
+		return (((code == VDO_ADMIN_STATE_SUSPENDED) ||
+			 (code == VDO_ADMIN_STATE_SAVED)) ? code : NULL);
+	}
+
+	return VDO_ADMIN_STATE_NORMAL_OPERATION;
+}
+
+/**
+ * vdo_finish_operation() - Finish the current operation.
+ * @state: The current admin state.
+ * @result: The result of the operation.
+ *
+ * Will notify the operation waiter if there is one. This method should be used for operations
+ * started with vdo_start_operation(). For operations which were started with vdo_start_draining(),
+ * use vdo_finish_draining() instead.
+ *
+ * Return: true if there was an operation to finish.
+ */
+bool vdo_finish_operation(struct admin_state *state, int result)
+{
+	if (!vdo_get_admin_state_code(state)->operating)
+		return false;
+
+	state->complete = state->starting;
+	if (state->waiter != NULL)
+		vdo_set_completion_result(state->waiter, result);
+
+	if (!state->starting) {
+		vdo_set_admin_state_code(state, state->next_state);
+		if (state->waiter != NULL)
+			vdo_launch_completion(vdo_forget(state->waiter));
+	}
+
+	return true;
+}
+
+/**
+ * begin_operation() - Begin an operation if it may be started given the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ * @waiter: A completion to notify when the operation is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+static int __must_check begin_operation(struct admin_state *state,
+					const struct admin_state_code *operation,
+					struct vdo_completion *waiter,
+					vdo_admin_initiator_fn initiator)
+{
+	int result;
+	const struct admin_state_code *next_state = get_next_state(state, operation);
+
+	if (next_state == NULL) {
+		result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
+						"Can't start %s from %s",
+						operation->name,
+						vdo_get_admin_state_code(state)->name);
+	} else if (state->waiter != NULL) {
+		result = vdo_log_error_strerror(VDO_COMPONENT_BUSY,
+						"Can't start %s with extant waiter",
+						operation->name);
+	} else {
+		state->waiter = waiter;
+		state->next_state = next_state;
+		vdo_set_admin_state_code(state, operation);
+		if (initiator != NULL) {
+			state->starting = true;
+			initiator(state);
+			state->starting = false;
+			if (state->complete)
+				vdo_finish_operation(state, VDO_SUCCESS);
+		}
+
+		return VDO_SUCCESS;
+	}
+
+	if (waiter != NULL)
+		vdo_continue_completion(waiter, result);
+
+	return result;
+}
+
+/**
+ * start_operation() - Start an operation if it may be started given the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ * @waiter: A completion to notify when the operation is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the operation was started.
+ */
+static inline bool __must_check start_operation(struct admin_state *state,
+						const struct admin_state_code *operation,
+						struct vdo_completion *waiter,
+						vdo_admin_initiator_fn initiator)
+{
+	return (begin_operation(state, operation, waiter, initiator) == VDO_SUCCESS);
+}
+
+/**
+ * check_code() - Check the result of a state validation.
+ * @valid: True if the code is of an appropriate type.
+ * @code: The code which failed to be of the correct type.
+ * @what: What the code failed to be, for logging.
+ * @waiter: The completion to notify of the error; may be NULL.
+ *
+ * If the result failed, log an invalid state error and, if there is a waiter, notify it.
+ *
+ * Return: The result of the check.
+ */
+static bool check_code(bool valid, const struct admin_state_code *code, const char *what,
+		       struct vdo_completion *waiter)
+{
+	int result;
+
+	if (valid)
+		return true;
+
+	result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
+					"%s is not a %s", code->name, what);
+	if (waiter != NULL)
+		vdo_continue_completion(waiter, result);
+
+	return false;
+}
+
+/**
+ * assert_vdo_drain_operation() - Check that an operation is a drain.
+ * @operation: The operation to check.
+ * @waiter: The completion to finish with an error if the operation is not a drain.
+ *
+ * Return: true if the specified operation is a drain.
+ */
+static bool __must_check assert_vdo_drain_operation(const struct admin_state_code *operation,
+						    struct vdo_completion *waiter)
+{
+	return check_code(operation->draining, operation, "drain operation", waiter);
+}
+
+/**
+ * vdo_start_draining() - Initiate a drain operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of drain to initiate.
+ * @waiter: The completion to notify when the drain is complete.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the drain was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_draining(struct admin_state *state,
+			const struct admin_state_code *operation,
+			struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	const struct admin_state_code *code = vdo_get_admin_state_code(state);
+
+	if (!assert_vdo_drain_operation(operation, waiter))
+		return false;
+
+	if (code->quiescent) {
+		vdo_launch_completion(waiter);
+		return false;
+	}
+
+	if (!code->normal) {
+		vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE, "can't start %s from %s",
+				       operation->name, code->name);
+		vdo_continue_completion(waiter, VDO_INVALID_ADMIN_STATE);
+		return false;
+	}
+
+	return start_operation(state, operation, waiter, initiator);
+}
+
+/**
+ * vdo_finish_draining() - Finish a drain operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was draining; will notify the waiter if so.
+ */
+bool vdo_finish_draining(struct admin_state *state)
+{
+	return vdo_finish_draining_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_draining_with_result() - Finish a drain operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the drain operation.
+ *
+ * Return: true if the state was draining; will notify the waiter if so.
+ */
+bool vdo_finish_draining_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_draining(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * vdo_assert_load_operation() - Check that an operation is a load.
+ * @operation: The operation to check.
+ * @waiter: The completion to finish with an error if the operation is not a load.
+ *
+ * Return: true if the specified operation is a load.
+ */
+bool vdo_assert_load_operation(const struct admin_state_code *operation,
+			       struct vdo_completion *waiter)
+{
+	return check_code(operation->loading, operation, "load operation", waiter);
+}
+
+/**
+ * vdo_start_loading() - Initiate a load operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of load to initiate.
+ * @waiter: The completion to notify when the load is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the load was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_loading(struct admin_state *state,
+		       const struct admin_state_code *operation,
+		       struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	return (vdo_assert_load_operation(operation, waiter) &&
+		start_operation(state, operation, waiter, initiator));
+}
+
+/**
+ * vdo_finish_loading() - Finish a load operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was loading; will notify the waiter if so.
+ */
+bool vdo_finish_loading(struct admin_state *state)
+{
+	return vdo_finish_loading_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_loading_with_result() - Finish a load operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the load operation.
+ *
+ * Return: true if the state was loading; will notify the waiter if so.
+ */
+bool vdo_finish_loading_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_loading(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * assert_vdo_resume_operation() - Check whether an admin_state_code is a resume operation.
+ * @operation: The operation to check.
+ * @waiter: The completion to notify if the operation is not a resume operation; may be NULL.
+ *
+ * Return: true if the code is a resume operation.
+ */
+static bool __must_check assert_vdo_resume_operation(const struct admin_state_code *operation,
+						     struct vdo_completion *waiter)
+{
+	return check_code(operation == VDO_ADMIN_STATE_RESUMING, operation,
+			  "resume operation", waiter);
+}
+
+/**
+ * vdo_start_resuming() - Initiate a resume operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of resume to start.
+ * @waiter: The completion to notify when the resume is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the resume was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_resuming(struct admin_state *state,
+			const struct admin_state_code *operation,
+			struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	return (assert_vdo_resume_operation(operation, waiter) &&
+		start_operation(state, operation, waiter, initiator));
+}
+
+/**
+ * vdo_finish_resuming() - Finish a resume operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was resuming; will notify the waiter if so.
+ */
+bool vdo_finish_resuming(struct admin_state *state)
+{
+	return vdo_finish_resuming_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_resuming_with_result() - Finish a resume operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the resume operation.
+ *
+ * Return: true if the state was resuming; will notify the waiter if so.
+ */
+bool vdo_finish_resuming_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_resuming(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * vdo_resume_if_quiescent() - Change the state to normal operation if the current state is
+ *                             quiescent.
+ * @state: The current admin state.
+ *
+ * Return: VDO_SUCCESS if the state resumed, VDO_INVALID_ADMIN_STATE otherwise.
+ */
+int vdo_resume_if_quiescent(struct admin_state *state)
+{
+	if (!vdo_is_state_quiescent(state))
+		return VDO_INVALID_ADMIN_STATE;
+
+	vdo_set_admin_state_code(state, VDO_ADMIN_STATE_NORMAL_OPERATION);
+	return VDO_SUCCESS;
+}
+
+/**
+ * vdo_start_operation() - Attempt to start an operation.
+ * @state: The current admin state.
+ * @operation: The operation to attempt to start.
+ *
+ * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
+ */
+int vdo_start_operation(struct admin_state *state,
+			const struct admin_state_code *operation)
+{
+	return vdo_start_operation_with_waiter(state, operation, NULL, NULL);
+}
+
+/**
+ * vdo_start_operation_with_waiter() - Attempt to start an operation.
+ * @state: The current admin state.
+ * @operation: The operation to attempt to start.
+ * @waiter: The completion to notify when the operation completes or fails to start; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
+ */
+int vdo_start_operation_with_waiter(struct admin_state *state,
+				    const struct admin_state_code *operation,
+				    struct vdo_completion *waiter,
+				    vdo_admin_initiator_fn initiator)
+{
+	return (check_code(operation->operating, operation, "operation", waiter) ?
+		begin_operation(state, operation, waiter, initiator) :
+		VDO_INVALID_ADMIN_STATE);
+}