Bluetooth: controller: Fix ticker to avoid recursive ticker_job #32752
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Consider also moving clearing of the job_guard to after ticker_job_compare_update
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Is this because ticks_slot_previous and ticks_current are updated in ticker_job_compare_update, and the vectoring (swap) to ticker_worker function would use stale values? or do you have other reasons?
(sorry for asking again, from the message here: #31026 (comment), I understand context-safety, but just making double sure :-) ).
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Is this because
ticks_slot_previousandticks_currentare updated inticker_job_compare_update, and the vectoring (swap) toticker_workerfunction would use stale values? or do you have other reasons?
Yes, that is exactly why. The suggestion is not based on an actual observation, just based on analysis and being cautious.
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Agreed. Your analysis is correct, as the resolution happens in ticker_worker, there are chances that after a current reserving ticker is stopped, it is necessary to have correct value of ticks_slot_previous and ticks_current be used in the ticker_worker.
Fix ticker job to defer itself to avoid recursive invocation to itself due to ticker interface calls from inside the ticker operation callbacks. The recursive use was exposed when using ticker stop operation callback of stopping an auxiliary PDU to stop the primary PDU scheduling as part of generation of Advertising Terminate event. Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>
Move the ticker job_guard reset to after ticker_job_compare_update, so that the ticks_current and ticks_slot_previous are updated before ticker_worker gets to execute. Without this fix, there is a possibility that ticker_worker will use incorrect ticks_slot_previous and ticks_current value under race conditions. Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>
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Fix ticker job to defer itself to avoid recursive
invocation to itself due to ticker interface calls from
inside the ticker operation callbacks.
The recursive use was exposed when using ticker stop
operation callback of stopping an auxiliary PDU to stop
the primary PDU scheduling as part of generation of
Advertising Terminate event.
Signed-off-by: Vinayak Kariappa Chettimada [email protected]