There are certain guidelines and restrictions that need to be followed to ensure proper and efficient interrupt handling.
- Handler should be short and fast: The implemented interrupt handlers should be simple, concise and execute quickly. They should perform the necessary minimal stuffs which are mainly required to serve the interrupt service and can defer any lengthy operations or time-consuming to a bottom half's.
- Use dedicated interrupt-safe data structures: Ensure to access safe and dedicated shared data structures If interrupt handler needs to use it. Follow using spinlocks, atomic operations, or other synchronization mechanisms to prevent data corruption or race conditions.
- Disable interrupts when modifying shared data: I's important to disable interrupts (using local_irq_disable() or similar functions) to prevent concurrent access and ensure data consistency. If ISR routine needs to modify shared data structures that are also need to access in other contexts.
- Avoid usage of blockage methods during data transfer: If the interrupt handler needs to synchronize with other parts of the kernel or user space to do data transfer, avoid use of blockage methods like copy to/form user() methods (or any similar methods which can have good/bad page faults) and choose the appropriate synchronization mechanisms like spinlocks, semaphores, mutexes, or atomic operations based on the requirements and context. Blocking or sleeping operations are not allowed and these can lead to increased interrupt latency and system can become unresponsiveness sometime by causing deadlocks or resource conflicts within the kernel.
- Avoid use of print statements or any similar types: Avoid use of any kind of log messages or print statements (or any similar statements) which can delay the ISR and degrade the performance.