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Kernel: Some futex improvements

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This adds support for FUTEX_WAKE_OP, FUTEX_WAIT_BITSET, FUTEX_WAKE_BITSET,
FUTEX_REQUEUE, and FUTEX_CMP_REQUEUE, as well well as global and private
futex and absolute/relative timeouts against the appropriate clock. This
also changes the implementation so that kernel resources are only used when
a thread is blocked on a futex.

Global futexes are implemented as offsets in VMObjects, so that different
processes can share a futex against the same VMObject despite potentially
being mapped at different virtual addresses.
This commit is contained in:
Tom 2020-12-21 23:21:58 -07:00 • committed by Andreas Kling
parent 7581b64705
commit 1d621ab172
23 changed files with 928 additions and 63 deletions
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67
Kernel/FutexQueue.h Normal file
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/*
* Copyright (c) 2020, The SerenityOS developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/Atomic.h>
#include <AK/RefCounted.h>
#include <Kernel/SpinLock.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/VMObject.h>
namespace Kernel {
class FutexQueue : public Thread::BlockCondition
, public RefCounted<FutexQueue>
, public VMObjectDeletedHandler {
public:
FutexQueue(FlatPtr user_address_or_offset, VMObject* vmobject = nullptr);
virtual ~FutexQueue();
u32 wake_n_requeue(u32, const Function<FutexQueue*()>&, u32, bool&, bool&);
u32 wake_n(u32, const Optional<u32>&, bool&);
u32 wake_all(bool&);
template<class... Args>
Thread::BlockResult wait_on(const Thread::BlockTimeout& timeout, Args&&... args)
{
return Thread::current()->block<Thread::FutexBlocker>(timeout, *this, forward<Args>(args)...);
}
virtual void vmobject_deleted(VMObject&) override;
protected:
virtual bool should_add_blocker(Thread::Blocker& b, void* data) override;
private:
// For private futexes we just use the user space address.
// But for global futexes we use the offset into the VMObject
const FlatPtr m_user_address_or_offset;
WeakPtr<VMObject> m_vmobject;
const bool m_is_global;
};
}