qemu/include/sysemu/reset.h
Peter Maydell 71b3ea373b hw/core/reset: Implement qemu_register_reset via qemu_register_resettable
Reimplement qemu_register_reset() via qemu_register_resettable().

We define a new LegacyReset object which implements Resettable and
defines its reset hold phase method to call a QEMUResetHandler
function.  When qemu_register_reset() is called, we create a new
LegacyReset object and add it to the simulation_reset
ResettableContainer.  When qemu_unregister_reset() is called, we find
the LegacyReset object in the container and remove it.

This implementation of qemu_unregister_reset() means we'll end up
scanning the ResetContainer's list of child objects twice, once
to find the LegacyReset object, and once in g_ptr_array_remove().
In theory we could avoid this by having the ResettableContainer
interface include a resettable_container_remove_with_equal_func()
that took a callback method so that we could use
g_ptr_array_find_with_equal_func() and g_ptr_array_remove_index().
But we don't expect qemu_unregister_reset() to be called frequently
or in hot paths, and we expect the simulation_reset container to
usually not have many children.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20240220160622.114437-9-peter.maydell@linaro.org
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
2024-02-27 13:01:42 +00:00

127 lines
4.8 KiB
C

/*
* Reset handlers.
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2016 Red Hat, Inc.
* Copyright (c) 2024 Linaro, Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef QEMU_SYSEMU_RESET_H
#define QEMU_SYSEMU_RESET_H
#include "qapi/qapi-events-run-state.h"
typedef void QEMUResetHandler(void *opaque);
/**
* qemu_register_resettable: Register an object to be reset
* @obj: object to be reset: it must implement the Resettable interface
*
* Register @obj on the list of objects which will be reset when the
* simulation is reset. These objects will be reset in the order
* they were added, using the three-phase Resettable protocol,
* so first all objects go through the enter phase, then all objects
* go through the hold phase, and then finally all go through the
* exit phase.
*
* It is not permitted to register or unregister reset functions or
* resettable objects from within any of the reset phase methods of @obj.
*
* We assume that the caller holds the BQL.
*/
void qemu_register_resettable(Object *obj);
/**
* qemu_unregister_resettable: Unregister an object to be reset
* @obj: object to unregister
*
* Remove @obj from the list of objects which are reset when the
* simulation is reset. It must have been previously added to
* the list via qemu_register_resettable().
*
* We assume that the caller holds the BQL.
*/
void qemu_unregister_resettable(Object *obj);
/**
* qemu_register_reset: Register a callback for system reset
* @func: function to call
* @opaque: opaque data to pass to @func
*
* Register @func on the list of functions which are called when the
* entire system is reset. Functions registered with this API and
* Resettable objects registered with qemu_register_resettable() are
* handled together, in the order in which they were registered.
* Functions registered with this API are called in the 'hold' phase
* of the 3-phase reset.
*
* In general this function should not be used in new code where possible;
* for instance, device model reset is better accomplished using the
* methods on DeviceState.
*
* It is not permitted to register or unregister reset functions or
* resettable objects from within the @func callback.
*
* We assume that the caller holds the BQL.
*/
void qemu_register_reset(QEMUResetHandler *func, void *opaque);
/**
* qemu_register_reset_nosnapshotload: Register a callback for system reset
* @func: function to call
* @opaque: opaque data to pass to @func
*
* This is the same as qemu_register_reset(), except that @func is
* not called if the reason that the system is being reset is to
* put it into a clean state prior to loading a snapshot (i.e. for
* SHUTDOWN_CAUSE_SNAPSHOT_LOAD).
*/
void qemu_register_reset_nosnapshotload(QEMUResetHandler *func, void *opaque);
/**
* qemu_unregister_reset: Unregister a system reset callback
* @func: function registered with qemu_register_reset()
* @opaque: the same opaque data that was passed to qemu_register_reset()
*
* Undo the effects of a qemu_register_reset(). The @func and @opaque
* must both match the arguments originally used with qemu_register_reset().
*
* We assume that the caller holds the BQL.
*/
void qemu_unregister_reset(QEMUResetHandler *func, void *opaque);
/**
* qemu_devices_reset: Perform a complete system reset
* @reason: reason for the reset
*
* This function performs the low-level work needed to do a complete reset
* of the system (calling all the callbacks registered with
* qemu_register_reset() and resetting all the Resettable objects registered
* with qemu_register_resettable()). It should only be called by the code in a
* MachineClass reset method.
*
* If you want to trigger a system reset from, for instance, a device
* model, don't use this function. Use qemu_system_reset_request().
*/
void qemu_devices_reset(ShutdownCause reason);
#endif