hujun260 opened a new pull request, #18207:
URL: https://github.com/apache/nuttx/pull/18207
## Summary
Consolidate multiple return statements in the `down_write_trylock()`
function
into a single exit point to improve code quality and comply with MISRA HIS
coding standards for safety-critical systems.
## Motivation and Problem
The original implementation had multiple return points (early return for
failure
and return at the end for success), 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 improves maintainability and compliance with automotive safety
standards.
## Changes
- Introduce a result variable (`ret`) initialized to 1 (success)
- Replace early error return with assignment to `ret = 0`
- Wrap the success path in an else block to maintain control flow clarity
- Perform single return at function end with the result variable
## Impact
- **Code Quality**: Reduced cyclomatic complexity
- **Compliance**: Achieves MISRA HIS compliance for return statement metrics
- **Verifiability**: Single exit point improves static analysis and code
verification
- **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] Reader-writer semaphore trylock behavior unchanged
- [x] Success path (return 1) verified
- [x] Failure path (return 0) verified
- [x] Mutex protection and holder tracking verified
- [x] Static analysis shows improved complexity metrics
## Testing
Tested with:
- ARM GCC 10.x compiler
- QEMU ARMv7-A simulation
- Reader-writer semaphore operations:
- Write lock acquisition attempts
- Concurrent reader detection
- Recursive writer holder detection
- Lock state transitions
## Files Changed
- `sched/semaphore/sem_rw.c` (17 lines: 10 insertions, 7 deletions)
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
