71bdf2820e
It's been a long standing problem that init calls fs_mgr functions
synchronously and therefore stops handling properties, which causes
deadlocks if either fs_mgr, or vdc, or vold attempt to set
properties.
Previous work, b/21904461, shows that there is a large performance
penalty for adding any amount of locking to properties, so moving
property service into its own thread generically is not a viable
option. However, we can be sure that init is not setting properties
while the fs_mgr functions are running, so we can poll the property
socket in a thread while we call these functions.
The other alternative would have been to separate the fs_mgr functions
into smaller pieces and revisit the main init loop between each
piece. Unfortunately, this would be difficult, since
fs_mgr_mount_all() calls out to different processes via logwrapper,
which synchronously polls on a logging FD from the child, among other
complexities that would make this strategy much more difficult than it
would be worth.
Bug: 21904461
Test: device boots, including when setting property in
fs_mgr_mount_all()
Change-Id: Ib0b7123024035884f9d90f9b489c1e2f5a2e1707
51 lines
1.6 KiB
C++
51 lines
1.6 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <sys/socket.h>
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#include <functional>
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#include <string>
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#include "epoll.h"
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#include "result.h"
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namespace android {
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namespace init {
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bool CanReadProperty(const std::string& source_context, const std::string& name);
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extern uint32_t (*property_set)(const std::string& name, const std::string& value);
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uint32_t HandlePropertySet(const std::string& name, const std::string& value,
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const std::string& source_context, const ucred& cr, std::string* error);
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void property_init();
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void property_load_boot_defaults(bool load_debug_prop);
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void load_persist_props();
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void StartPropertyService(Epoll* epoll);
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template <typename F, typename... Args>
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Result<int> CallFunctionAndHandleProperties(F&& f, Args&&... args) {
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Result<int> CallFunctionAndHandlePropertiesImpl(const std::function<int()>& f);
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auto func = [&] { return f(args...); };
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return CallFunctionAndHandlePropertiesImpl(func);
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}
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} // namespace init
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} // namespace android
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