diff --git a/Kernel/Lock.cpp b/Kernel/Lock.cpp new file mode 100644 index 00000000000..bd7e35d7194 --- /dev/null +++ b/Kernel/Lock.cpp @@ -0,0 +1,70 @@ +#include + +void Lock::lock() +{ + if (!are_interrupts_enabled()) { + kprintf("Interrupts disabled when trying to take Lock{%s}\n", m_name); + dump_backtrace(); + hang(); + } + ASSERT(!Scheduler::is_active()); + for (;;) { + if (CAS(&m_lock, 1, 0) == 0) { + if (!m_holder || m_holder == current) { + m_holder = current; + ++m_level; + memory_barrier(); + m_lock = 0; + return; + } + m_lock = 0; + } + Scheduler::donate_to(m_holder, m_name); + } +} + +void Lock::unlock() +{ + for (;;) { + if (CAS(&m_lock, 1, 0) == 0) { + ASSERT(m_holder == current); + ASSERT(m_level); + --m_level; + if (m_level) { + memory_barrier(); + m_lock = 0; + return; + } + m_holder = nullptr; + memory_barrier(); + m_lock = 0; + return; + } + Scheduler::donate_to(m_holder, m_name); + } +} + +bool Lock::unlock_if_locked() +{ + for (;;) { + if (CAS(&m_lock, 1, 0) == 0) { + if (m_level == 0) { + memory_barrier(); + m_lock = 0; + return false; + } + ASSERT(m_holder == current); + ASSERT(m_level); + --m_level; + if (m_level) { + memory_barrier(); + m_lock = 0; + return false; + } + m_holder = nullptr; + memory_barrier(); + m_lock = 0; + return true; + } + } +}