hujun260 opened a new pull request, #17958:
URL: https://github.com/apache/nuttx/pull/17958
## Summary
Add null-check protection for ISR handler invocation in threaded interrupt
mode. When `isr` is NULL, the system now safely handles the irq_default_handler
without attempting to call a null function pointer. This improves robustness of
the interrupt handling subsystem and aligns with the documented behavior that
NULL ISR triggers isrthread execution.
## Changes
- **sched/irq/irq_attach_thread.c**:
- Replace `DEBUGASSERT(info->handler != NULL)` with safe null-check
conditional
- Only invoke handler if non-NULL, preventing potential null pointer
dereference
- Update comment documentation to clarify behavior when isr is NULL
- **sched/irq/irq_attach_wqueue.c**:
- Add null-check guard for info->handler before invocation
- Initialize `ret` variable to `IRQ_WAKE_THREAD` for correct default
behavior
- Fix handler call parameter from generic `arg` to `info->arg` for
consistency
- Update comment to accurately reflect NULL isr behavior
## Benefits & Technical Details
- **Safety**: Eliminates null pointer dereference risk when NULL ISR is
passed during handler attachment/detachment
- **Documentation alignment**: Comment now accurately reflects
implementation - NULL isr triggers isrthread callback
- **Consistency**: Both irq_attach_thread and irq_attach_wqueue use
identical null-check pattern
- **Correct parameter passing**: Fixed parameter type in irq_attach_wqueue
to pass correct context data
## Testing
- Verified irq_default_handler correctly handles NULL handler pointers
without crashing
- Confirmed isrthread is properly invoked when isr is NULL during IRQ
attachment
- Tested IRQ attachment and detachment with both NULL and non-NULL ISR
handlers
- Validated on systems with threaded and work queue based interrupt handlers
## Impact
- **Robustness**: Safer interrupt handler attachment/detachment sequence
- **Compatibility**: No API changes, fully backward compatible
- **Documentation**: Corrected and clarified ISR NULL handling behavior
- **Scope**: Affects threaded interrupt mode
(CONFIG_ARCH_IRQHANDLER_ATTACH_THREAD) and work queue based IRQ handling
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