hujun260 opened a new pull request, #18240:
URL: https://github.com/apache/nuttx/pull/18240
# Title: sched_sysinfo: Initialize cpuload structure to resolve MISRA C 2012
Rule 9.1
## Summary
Refactor the system information retrieval function to improve code quality
by initializing the `cpuload_s` structure with zero values at declaration. This
change resolves a MISRA C 2012 Rule 9.1 violation (uninitialized variable
usage) and ensures reliable system information retrieval.
## Motivation and Problem
MISRA C 2012 Rule 9.1 requires that all variables should be initialized
before use. The original `sysinfo()` function declared the `cpuload` structure
without initialization, creating a potential code quality issue and violating
safety standards even though the variable might be properly populated later.
### Safety Standard Compliance
- **MISRA C 2012 Rule 9.1**: All variables must be initialized before use
- **Defect Type**: Uninitialized variable usage (uninit_use)
- **Risk**: Unpredictable values if code paths change or maintenance occurs
- **Benefit**: Ensures consistent, safe initialization of system data
structures
## Changes Made
1. **Variable Initialization**: Initialize `cpuload` structure at declaration
- Changed from uninitialized to explicitly initialized with zero values
- Proper aggregate initialization syntax using designated initializers
2. **Initialization Values**: Set both structure members to 0
- Represents no CPU load samples yet taken
- Consistent with expected initial state
3. **Code Organization**: Improved readability with proper formatting
- Multi-line initialization for clarity
- Better adherence to coding standards
### File Statistics
- **File Modified**: `sched/sched/sched_sysinfo.c`
- **Lines Changed**: 7 (6 insertions, 1 deletion)
- **Type**: Code improvement for safety compliance
## Impact Analysis
✅ **Backward Compatibility**: MAINTAINED - Same functionality and behavior
✅ **Code Quality**: IMPROVED - Initialized variables ensure predictability
✅ **MISRA Compliance**: ACHIEVED - Rule 9.1 violation resolved
✅ **Safety**: ENHANCED - Eliminates uninitialized data risk
✅ **Performance**: NO IMPACT - Initialization minimal overhead
## Verification Checklist
- [x] Compilation successful with all warning flags
- [x] sysinfo() returns correct system information
- [x] CPU load values correctly reported when available
- [x] CPU load values safe when CONFIG_SCHED_CPULOAD_NONE enabled
- [x] No impact on system information accuracy
- [x] MISRA C 2012 Rule 9.1 compliance verified
- [x] Code review completed
## Testing Scenarios
1. **System Information Retrieval**: Verify sysinfo() returns valid data
2. **CPU Load Monitoring**: Test CPU load fields with
CONFIG_SCHED_CPULOAD_NONE disabled
3. **Disabled CPU Load**: Test behavior with CONFIG_SCHED_CPULOAD_NONE
enabled
4. **Memory Information**: Verify memory-related system info unchanged
5. **Process Information**: Test process count and state reporting
6. **Architecture Coverage**: Test on ARM platforms
## Technical Notes
- Structure initialized with explicit zero values (0, 0)
- Both members of cpuload_s set to 0 initially
- Multi-line initialization improves code readability
- Initialization occurs every function call but with minimal overhead
- Safe even if subsequent code paths modified in future maintenance
## Related Issues
- **Category**: Code Quality & Safety Standard Compliance
- **Standard**: MISRA C 2012 Rule 9.1 (Uninitialized Variables)
- **Defect Type**: uninit_use (uninitialized variable usage)
- **Subsystem**: Kernel scheduler - system information (sched/sched/)
## Build Information
- **Compiler**: ARM GCC 10.x (primary test environment)
- **Architectures**: ARMv7-A, ARMv7-R, x86_64
- **Target**: NuttX kernel - scheduler subsystem (sched/)
- **Build Flags**: `-Wall -Wextra -Werror`
- **Configuration**: CONFIG_SCHED_CPULOAD_NONE configurable
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