hujun260 opened a new pull request, #18213:
URL: https://github.com/apache/nuttx/pull/18213
## Summary
Eliminate goto-based control flow in the `nxsem_tickwait()` function by
replacing
it with structured if-else blocks to achieve MISRA HIS compliance while
maintaining
identical functional behavior and improving code readability.
## Motivation and Problem
The original implementation used goto statements to handle control flow and
resource
cleanup, which violates MISRA HIS coding standards for safety-critical
systems.
These standards promote structured programming with single entry and exit
points
to improve code verification and reduce defects. Replacing goto with
structured
if-else blocks improves code clarity, verifiability, and compliance with
automotive
safety standards.
## Changes
- Replace early return goto with inverted condition check (ret != OK)
- Replace timeout handling goto with nested if-else structure
- Move timeout and semaphore wait logic into properly nested blocks
- Eliminate the out: label and centralize exit at function end
- Maintain identical semantics: critical section is still entered/exited
correctly
## Impact
- **Compliance**: Achieves MISRA HIS compliance for goto elimination metrics
- **Code Quality**: Improved readability with structured control flow
- **Verifiability**: Easier static analysis and formal verification
- **Maintainability**: Clear control flow without label jumps
- **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] Semaphore tickwait operations verified:
- Immediate success case (tryait succeeds)
- Zero delay timeout case
- Waiting with watchdog timer case
- [x] Critical section protection verified (interrupts disabled during
operation)
- [x] Watchdog timer start and cancel verified
- [x] Static analysis shows improved compliance metrics
## Testing
Tested with:
- ARM GCC 10.x compiler
- QEMU ARMv7-A simulation
- Semaphore tickwait scenarios:
- Semaphore available (immediate return)
- Zero delay timeout
- Waiting with timeout and watchdog protection
- Interrupt safety during critical sections
## Files Changed
- `sched/semaphore/sem_tickwait.c` (42 lines: 17 insertions, 25 deletions)
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