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MasterPTY's double buffer unblock callback would take m_slave's spinlock and then call evaluate_block_conditions() which would take BlockerSet's spinlock, while on the other hand, BlockerSet's add_blocker would take BlockerSet's spinlock, and then call should_add_blocker, which would call unblock_if_conditions_are_met, which would then call should_unblock, which will finally call MasterPTY::can_read() which will take m_slave's spinlock. Resolve this by moving the call to evaluate_block_conditions() out of the scope of m_slave's spinlock, as there's no need to hold the lock while calling it anyways.
57 lines
1.9 KiB
C++
57 lines
1.9 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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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/Badge.h>
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#include <Kernel/Devices/CharacterDevice.h>
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#include <Kernel/Library/DoubleBuffer.h>
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namespace Kernel {
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class SlavePTY;
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class MasterPTY final : public CharacterDevice {
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public:
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static ErrorOr<NonnullRefPtr<MasterPTY>> try_create(unsigned index);
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virtual ~MasterPTY() override;
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unsigned index() const { return m_index; }
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ErrorOr<size_t> on_slave_write(UserOrKernelBuffer const&, size_t);
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bool can_write_from_slave() const;
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void notify_slave_closed(Badge<SlavePTY>);
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bool is_closed() const { return m_closed; }
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virtual ErrorOr<NonnullOwnPtr<KString>> pseudo_path(OpenFileDescription const&) const override;
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private:
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explicit MasterPTY(unsigned index, NonnullOwnPtr<DoubleBuffer> buffer);
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// ^Device
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virtual bool is_openable_by_jailed_processes() const override { return true; }
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// ^CharacterDevice
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virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
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virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override;
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virtual bool can_read(OpenFileDescription const&, u64) const override;
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virtual bool can_write(OpenFileDescription const&, u64) const override;
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virtual ErrorOr<void> close() override;
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virtual bool is_master_pty() const override { return true; }
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virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
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virtual StringView class_name() const override { return "MasterPTY"sv; }
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bool has_slave() const
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{
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return m_slave.with([](auto& slave) -> bool { return slave; });
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}
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SpinlockProtected<RefPtr<SlavePTY>, LockRank::None> m_slave;
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unsigned m_index;
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bool m_closed { false };
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NonnullOwnPtr<DoubleBuffer> m_buffer;
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};
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}
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