hujun260 opened a new pull request, #18223:
URL: https://github.com/apache/nuttx/pull/18223
## Summary
Refactor the scheduler setting function to improve code quality by
eliminating goto statements and consolidating multiple return paths. The
implementation extracts sporadic scheduling logic into a dedicated function and
restructures parameter validation, resulting in improved code maintainability
and MISRA HIS compliance.
## Motivation and Problem
The original nxsched_set_scheduler() function used goto statements for error
handling and had multiple return paths scattered throughout the code, violating
MISRA HIS standards that require structured control flow and single exit point
patterns.
### Safety Standard Compliance
- **MISRA HIS Standard**: Eliminates goto statements; enforces
single-exit-point pattern
- **Coverity Defect**: HIS_metric_violation (RETURN) - Multiple return paths
and goto detected
- **Code Restructuring**: Moves early validations and error returns into
structured code blocks
- **Benefit**: Enhanced code verifiability, reduced control flow complexity,
improved maintainability
## Changes Made
1. **Function Extraction**: Extract sporadic scheduling logic into separate
`process_sporadic()` function
- Reduces nesting complexity in main scheduler function
- Improves code readability and reusability
2. **Parameter Validation Restructuring**: Move early policy and priority
validation into conditional block
- Consolidated validation checks into unified decision point
- Reduced early return statements
3. **Goto Elimination**: Replace error handling goto statements with
structured if-else blocks
- Removed `errout_with_irq:` label and associated goto jumps
- Maintains same functional behavior with cleaner control flow
4. **Single Exit Point**: Consolidate all code paths to use single return
statement
- All error conditions set return value
- Uniform cleanup and resource release
5. **Code Reorganization**:
- Move sporadic scheduling code to dedicated helper function
- Restructure policy switch statement within validation block
- Improve indentation and code clarity
### File Statistics
- **File Modified**: `sched/sched/sched_setscheduler.c`
- **Lines Changed**: 312 (154 insertions, 158 deletions)
- **Type**: Major code restructuring for compliance improvement
## Impact Analysis
✅ **Backward Compatibility**: MAINTAINED - Function behavior unchanged
✅ **Code Quality**: SIGNIFICANTLY IMPROVED - Goto elimination, single exit
point
✅ **MISRA Compliance**: RESOLVED - HIS_metric_violation defect fixed
✅ **Readability**: ENHANCED - Clearer code structure and logic flow
✅ **Maintainability**: IMPROVED - Extracted sporadic function, reduced
complexity
✅ **Performance**: NO IMPACT - Same scheduling logic, improved structure
## Verification Checklist
- [x] Compilation successful with all warning flags enabled
- [x] All scheduling policies correctly handled (SCHED_FIFO, SCHED_RR,
SCHED_SPORADIC, SCHED_OTHER)
- [x] Parameter validation preserved and restructured correctly
- [x] Sporadic scheduling extracted to separate function without behavioral
changes
- [x] No goto statements in refactored code
- [x] Single exit point pattern implemented and verified
- [x] Error return codes preserved (-EINVAL, -ESRCH)
- [x] Coverity HIS_metric_violation (RETURN) defect resolved
- [x] Code review completed - all logic paths validated
- [x] Integration testing completed
## Testing Scenarios
1. **Policy Validation**: Test invalid policy values properly rejected
2. **Priority Validation**: Test boundary conditions (SCHED_PRIORITY_MIN,
SCHED_PRIORITY_MAX)
3. **Task ID Validation**: Test invalid task IDs return -ESRCH
4. **FIFO Scheduling**: Verify SCHED_FIFO policy correctly applied
5. **Round-Robin Scheduling**: Test SCHED_RR with CONFIG_RR_INTERVAL settings
6. **Sporadic Scheduling**: Validate sporadic scheduling parameters and
initialization
7. **Sporadic Parameter Extraction**: Test process_sporadic() function
independently
8. **Context Switching**: Verify critical section protection during policy
change
9. **Priority Update**: Confirm nxsched_reprioritize() called after policy
change
10. **Edge Cases**: Test with concurrent policy changes across multiple tasks
## Technical Notes
- Sporadic scheduling parameter validation moved to `process_sporadic()`
function
- All validation paths consolidated into single nested conditional structure
- Critical section (enter/leave_critical_section) usage preserved and
maintained
- Task lookup and locking sequence unchanged for consistency
- Error handling now uses structured if-else instead of goto labels
- All configuration-dependent code (#ifdef) preserved in switch statement
## Related Issues
- **Category**: Code Quality & Safety Standard Compliance
- **Standard**: MISRA HIS - Single Exit Point Pattern & Goto Elimination
- **Defect**: Coverity HIS_metric_violation (RETURN)
- **Subsystem**: Kernel scheduler - policy management (sched/sched/)
## Build Information
- **Compiler**: ARM GCC 10.x (primary test environment)
- **Architectures**: ARMv7-A, ARMv7-R, x86_64
- **Target**: NuttX kernel - scheduler subsystem
- **Build Flags**: `-Wall -Wextra -Werror`
- **Features**: CONFIG_SCHED_SPORADIC, CONFIG_RR_INTERVAL configurable
## Files Changed
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