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Kernel: Move Blocker setup out from constructors into setup_blocker()

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Instead of registering with blocker sets and whatnot in the various
Blocker subclass constructors, this patch moves such initialization
to a separate setup_blocker() virtual.

setup_blocker() returns false if there's no need to actually block
the thread. This allows us to bail earlier in Thread::block().
This commit is contained in:
Andreas Kling 2021-08-24 12:14:14 +02:00
parent c108c8ff24
commit 82c3cc4640
5 changed files with 92 additions and 39 deletions
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40
Kernel/Thread.h
View file

@ -300,6 +300,7 @@ public:
virtual Type blocker_type() const = 0;
virtual const BlockTimeout& override_timeout(const BlockTimeout& timeout) { return timeout; }
virtual bool can_be_interrupted() const { return true; }
virtual bool setup_blocker();
Thread& thread() { return m_thread; }
@ -523,11 +524,14 @@ public:
virtual bool should_block() override { return !m_join_error && m_should_block; }
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override;
virtual bool setup_blocker() override;
bool unblock(void*, bool);
private:
NonnullRefPtr<Thread> m_joinee;
void*& m_joinee_exit_value;
KResult& m_try_join_result;
bool m_join_error { false };
bool m_did_unblock { false };
bool m_should_block { true };
@ -541,15 +545,13 @@ public:
virtual Type blocker_type() const override { return Type::Queue; }
virtual StringView state_string() const override { return m_block_reason.is_null() ? m_block_reason : "Queue"sv; }
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override { }
virtual bool should_block() override
{
return m_should_block;
}
virtual bool should_block() override { return m_should_block; }
virtual bool setup_blocker() override;
bool unblock();
protected:
WaitQueue& m_wait_queue;
StringView m_block_reason;
bool m_should_block { true };
bool m_did_unblock { false };
@ -563,11 +565,8 @@ public:
virtual Type blocker_type() const override { return Type::Futex; }
virtual StringView state_string() const override { return "Futex"sv; }
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override { }
virtual bool should_block() override
{
return m_should_block;
}
virtual bool should_block() override { return m_should_block; }
virtual bool setup_blocker() override;
u32 bitset() const { return m_bitset; }
@ -582,7 +581,8 @@ public:
bool unblock(bool force = false);
protected:
u32 m_bitset;
FutexQueue& m_futex_queue;
u32 m_bitset { 0 };
u32 m_relock_flags { 0 };
bool m_should_block { true };
bool m_did_unblock { false };
@ -627,6 +627,7 @@ public:
virtual bool unblock(bool, void*) override;
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override;
virtual bool setup_blocker() override;
protected:
explicit FileDescriptionBlocker(FileDescription&, BlockFlags, BlockFlags&);
@ -696,13 +697,14 @@ public:
};
typedef Vector<FDInfo, FD_SETSIZE> FDVector;
explicit SelectBlocker(FDVector& fds);
explicit SelectBlocker(FDVector&);
virtual ~SelectBlocker();
virtual bool unblock(bool, void*) override;
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override;
virtual void was_unblocked(bool) override;
virtual StringView state_string() const override { return "Selecting"sv; }
virtual bool setup_blocker() override;
private:
size_t collect_unblocked_flags();
@ -726,6 +728,7 @@ public:
virtual bool should_block() override { return m_should_block; }
virtual void will_unblock_immediately_without_blocking(UnblockImmediatelyReason) override;
virtual void was_unblocked(bool) override;
virtual bool setup_blocker() override;
bool unblock(Process& process, UnblockFlags flags, u8 signal, bool from_add_blocker);
bool is_wait() const { return !(m_wait_options & WNOWAIT); }
@ -867,6 +870,12 @@ public:
m_in_block = true;
BlockerType blocker(forward<Args>(args)...);
if (!blocker.setup_blocker()) {
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::UnblockConditionAlreadyMet);
m_in_block = false;
return BlockResult::NotBlocked;
}
SpinlockLocker scheduler_lock(g_scheduler_lock);
// Relaxed semantics are fine for timeout_unblocked because we
// synchronize on the spin locks already.
@ -885,13 +894,6 @@ public:
}
m_blocker = &blocker;
if (!blocker.should_block()) {
// Don't block if the wake condition is already met
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::UnblockConditionAlreadyMet);
m_blocker = nullptr;
m_in_block = false;
return BlockResult::NotBlocked;
}
auto& block_timeout = blocker.override_timeout(timeout);
if (!block_timeout.is_infinite()) {