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kIOFireWireCompleting
kIOFireWireCompleting indicates that the FireWire operation is already in its completion path. A second cancel, close, reuse, or completion action is therefore racing with an in-progress terminal transition.
Operational meaning
IOKit return values, internal tokens, and service messages share an integer representation but not the same control-flow meaning. Determine whether the API returns the value or delivers it as a message before treating it as failure.
Build a reproducible record
| Capture | Diagnostic value |
|---|---|
| Operation ID, completion callback, state transition, workloop/thread, bus generation, and second caller. | Identifies the concrete object and operation associated with FireWire operation already completing. |
| Numeric IOReturn/message value decoded with the matching SDK header. | Separates argument or lifecycle state from the provider beneath kIOFireWireCompleting. |
| Registry generation and first provider/client event before the result. | Ties the completion state to one request, callback sequence, and bus generation. |
| Known-good device or service state on the same macOS/driver build. | Shows whether kIOFireWireCompleting is the first result or a translated summary. |
Checks that separate the causes
- Serialize one request until its completion callback returns.
- Change one topology or lifecycle condition while keeping the request payload fixed.
- Verify cleanup and object lifetime after the controlled operation.
Resolution criteria
Targeted correction. Make completion single-owner and defer close/reuse until the terminal callback/state.
Acceptance criterion. Each request completes exactly once and concurrent cancel/close cannot reenter completion.
Technical references
- Apple XNU: IOReturn definitions — defines the status namespace used.
- Apple: IOKit documentation — documents the API or lifecycle boundary behind it.
- Apple OSS: XNU source — provides ABI, implementation, or protocol context.
- Apple XNU: FireWire family common definitions — supports the portability and verification limits.
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