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https://github.com/RGBCube/serenity
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a6a439243f
This step would ideally not have been necessary (increases amount of refactoring and templates necessary, which in turn increases build times), but it gives us a couple of nice properties: - SpinlockProtected inside Singleton (a very common combination) can now obtain any lock rank just via the template parameter. It was not previously possible to do this with SingletonInstanceCreator magic. - SpinlockProtected's lock rank is now mandatory; this is the majority of cases and allows us to see where we're still missing proper ranks. - The type already informs us what lock rank a lock has, which aids code readability and (possibly, if gdb cooperates) lock mismatch debugging. - The rank of a lock can no longer be dynamic, which is not something we wanted in the first place (or made use of). Locks randomly changing their rank sounds like a disaster waiting to happen. - In some places, we might be able to statically check that locks are taken in the right order (with the right lock rank checking implementation) as rank information is fully statically known. This refactoring even more exposes the fact that Mutex has no lock rank capabilites, which is not fixed here.
89 lines
3.3 KiB
C++
89 lines
3.3 KiB
C++
/*
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* Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/NonnullOwnPtr.h>
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#include <AK/OwnPtr.h>
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#include <AK/Stack.h>
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#include <Kernel/Locking/Spinlock.h>
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#include <Kernel/Memory/MemoryManager.h>
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#include <Kernel/Memory/Region.h>
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#include <Kernel/StdLib.h>
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namespace Kernel::USB {
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// This pool is bound by PAGE_SIZE / sizeof(T). The underlying allocation for the pointers
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// is AK::Stack. As such, we never dynamically allocate any memory past the amount
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// that can fit in a single page.
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template<typename T>
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class UHCIDescriptorPool {
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AK_MAKE_NONCOPYABLE(UHCIDescriptorPool);
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AK_MAKE_NONMOVABLE(UHCIDescriptorPool);
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// Ensure that we can't get into a situation where we'll write past the page
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// and blow up
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static_assert(sizeof(T) <= PAGE_SIZE);
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public:
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static ErrorOr<NonnullOwnPtr<UHCIDescriptorPool<T>>> try_create(StringView name)
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{
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auto pool_memory_block = TRY(MM.allocate_kernel_region(PAGE_SIZE, "UHCI Descriptor Pool"sv, Memory::Region::Access::ReadWrite));
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return adopt_nonnull_own_or_enomem(new (nothrow) UHCIDescriptorPool(move(pool_memory_block), name));
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}
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~UHCIDescriptorPool() = default;
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[[nodiscard]] T* try_take_free_descriptor()
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{
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SpinlockLocker locker(m_pool_lock);
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// We're out of descriptors!
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if (m_free_descriptor_stack.is_empty())
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return nullptr;
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dbgln_if(UHCI_VERBOSE_DEBUG, "Got a free UHCI Descriptor @ {} from pool {}", m_free_descriptor_stack.top(), m_pool_name);
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T* descriptor = m_free_descriptor_stack.top();
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m_free_descriptor_stack.pop();
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return descriptor;
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}
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void release_to_pool(T* ptr)
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{
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SpinlockLocker locker(m_pool_lock);
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dbgln_if(UHCI_VERBOSE_DEBUG, "Returning descriptor @ {} to pool {}", ptr, m_pool_name);
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if (!m_free_descriptor_stack.push(ptr))
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dbgln("Failed to return descriptor to pool {}. Stack overflow!", m_pool_name);
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}
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void print_pool_information() const
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{
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dbgln("Pool {} allocated @ {}", m_pool_name, m_pool_region->physical_page(0)->paddr());
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}
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private:
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UHCIDescriptorPool(NonnullOwnPtr<Memory::Region> pool_memory_block, StringView name)
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: m_pool_name(name)
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, m_pool_region(move(pool_memory_block))
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{
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// Go through the number of descriptors to create in the pool, and create a virtual/physical address mapping
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for (size_t i = 0; i < PAGE_SIZE / sizeof(T); i++) {
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auto* placement_address = reinterpret_cast<void*>(m_pool_region->vaddr().get() + (i * sizeof(T)));
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auto physical_address = static_cast<u32>(m_pool_region->physical_page(0)->paddr().get() + (i * sizeof(T)));
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auto* object = new (placement_address) T(physical_address);
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m_free_descriptor_stack.push(object); // Push the descriptor's pointer onto the free list
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}
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}
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StringView m_pool_name; // Name of this pool
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NonnullOwnPtr<Memory::Region> m_pool_region; // Memory region where descriptors actually reside
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Stack<T*, PAGE_SIZE / sizeof(T)> m_free_descriptor_stack; // Stack of currently free descriptor pointers
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Spinlock<LockRank::None> m_pool_lock;
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};
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}
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