hujun260 opened a new pull request, #18216:
URL: https://github.com/apache/nuttx/pull/18216
## Summary
Consolidate multiple return statements in the `nxsched_get_param()` function
into a single exit point and restructure error handling paths to reduce
cyclomatic
complexity and comply with MISRA HIS coding standards for safety-critical
systems.
## Motivation and Problem
The original implementation had multiple early return statements for error
cases,
which violates MISRA HIS metric rules for safety-critical code. This
increases
cyclomatic complexity and makes code verification and testing more difficult.
Consolidating returns to a single exit point and restructuring the control
flow
improves maintainability and compliance with automotive safety standards.
## Changes
- Introduce a result variable (`ret`) initialized to `OK`
- Replace early error returns with assignment to `ret` variable
- Restructure parameter validation to use if-else blocks instead of early
returns
- Consolidate task lookup and parameter retrieval logic within else blocks
- Perform single return at function end with the result variable
- Maintain identical functional behavior with improved code structure
## Impact
- **Code Quality**: Reduced cyclomatic complexity through single exit point
- **Compliance**: Achieves MISRA HIS compliance for return statement metrics
- **Verifiability**: Single exit point improves static analysis and code
verification
- **Maintainability**: Clearer control flow with nested conditions instead
of early returns
- **Backward Compatibility**: No functional changes; identical runtime
behavior
- **Performance**: No performance impact; compiler optimizations identical
## Verification
- [x] Code compiles without warnings on ARM GCC 10.x
- [x] Verified on QEMU ARMv7-A simulator with multimedia profile
- [x] Parameter retrieval for current task verified
- [x] Parameter retrieval for other tasks verified
- [x] Sporadic scheduling parameter handling verified
- [x] Error cases (invalid PID, NULL param) verified
- [x] Critical section protection verified
- [x] Static analysis shows improved complexity metrics
## Testing
Tested with:
- ARM GCC 10.x compiler
- QEMU ARMv7-A simulation
- Scheduling parameter operations:
- Get parameters for current task (pid == 0)
- Get parameters for running task (pid == rtcb->pid)
- Get parameters for other tasks
- Invalid PID error handling
- NULL parameter pointer error handling
- SCHED_SPORADIC parameter retrieval
- Non-sporadic priority parameter handling
## Files Changed
- `sched/sched/sched_getparam.c` (95 lines: 48 insertions, 47 deletions)
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