Improve EventFD Implementation: Performance, Safety, and Feature Enhancements

[TusharNaugain]

The current eventfd implementation has several limitations and potential issues that need to be addressed to improve reliability, performance, and functionality.

1. Thread Safety Concerns

Raw lock-based synchronization may cause unnecessary contention
Potential race conditions during counter updates
Lock holding during wait operations could cause priority inversion

2. Memory Management

No proper cleanup mechanism for resources
Potential memory leaks during error conditions
Direct manipulation of fd structure without proper encapsulation

3. Performance Bottlenecks

Excessive locking during read/write operations
Inefficient waiting mechanism
Unnecessary wake-ups for poll operations

4. Feature Limitations

Missing semaphore mode support
Limited flag options
No support for timeout operations
Lack of proper error reporting

5. Error Handling

Incomplete input validation
Missing edge case handling
Inadequate error reporting mechanisms

6. Documentation

Insufficient inline documentation
Missing API documentation
Lack of usage examples

[saagarjha]

This is not actionable.