hujun260 opened a new pull request, #18215:
URL: https://github.com/apache/nuttx/pull/18215
## Summary
Move the static `g_prof` variable declaration to block scope within the
`profil()`
function when CONFIG_SMP is disabled, to comply with MISRA C 2012 Rule 8.9
which
requires objects used by only one function to be declared within that
function's scope.
## Motivation and Problem
MISRA C 2012 Rule 8.9 enforces improved code locality by requiring that
objects
with internal linkage be declared at the smallest possible scope. The
original
code declared `g_prof` at file scope globally, even though it is only used
within
the `profil()` function when CONFIG_SMP is not enabled. When CONFIG_SMP is
enabled,
`g_prof` is used in SMP call data initialization, requiring file-scope
visibility.
This change optimizes the scope based on build configuration, improving code
clarity
and compliance with embedded systems coding standards.
## Changes
- Remove unconditional file-scope `static struct profinfo_s g_prof`
declaration
- Add conditional CONFIG_SMP block at file scope containing g_prof and
g_call_data
- Add local `static struct profinfo_s g_prof` declaration inside profil()
function
when CONFIG_SMP is disabled, restricting scope to only where it's used
## Impact
- **MISRA Compliance**: Achieves MISRA C 2012 Rule 8.9 compliance for scope
management
- **Code Quality**: Improves code locality and reduces global variable
exposure
- **Maintainability**: Clearer intent about variable usage within build
configurations
- **Verifiability**: Easier static analysis with properly scoped variables
- **Backward Compatibility**: No functional changes; identical runtime
behavior
- **Performance**: No performance impact; scope changes are compile-time only
## Verification
- [x] Code compiles without warnings on ARM GCC 10.x
- [x] Verified on QEMU ARMv7-A simulator with CONFIG_SMP disabled and enabled
- [x] Profiling functionality verified in both SMP and non-SMP configurations
- [x] Timer handler and profil function behavior unchanged
- [x] SMP-specific code paths verified in CONFIG_SMP builds
- [x] Static analysis shows improved compliance metrics
## Testing
Tested with:
- ARM GCC 10.x compiler
- QEMU ARMv7-A simulation
- Profiling scenarios:
- Non-SMP configuration (g_prof in profil() function scope)
- SMP configuration (g_prof at file scope with g_call_data)
- Timer handler invocation and profiling data collection
- Scale and offset parameter handling
## Files Changed
- `sched/sched/sched_profil.c` (6 lines: 4 insertions, 2 deletions)
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