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由 Marcel Holtmann 提交于
Due to a semantic changes in flush_workqueue() the current approach of synchronizing the sysfs handling for connections doesn't work anymore. The whole approach is actually fully broken and based on assumptions that are no longer valid. With the introduction of Simple Pairing support, the creation of low-level ACL links got changed. This change invalidates the reason why in the past two independent work queues have been used for adding/removing sysfs devices. The adding of the actual sysfs device is now postponed until the host controller successfully assigns an unique handle to that link. So the real synchronization happens inside the controller and not the host. The only left-over problem is that some internals of the sysfs device handling are not initialized ahead of time. This leaves potential access to invalid data and can cause various NULL pointer dereferences. To fix this a new function makes sure that all sysfs details are initialized when an connection attempt is made. The actual sysfs device is only registered when the connection has been successfully established. To avoid a race condition with the registration, the check if a device is registered has been moved into the removal work. As an extra protection two flush_work() calls are left in place to make sure a previous add/del work has been completed first. Based on a report by Marc Pignat <marc.pignat@hevs.ch> Signed-off-by: NMarcel Holtmann <marcel@holtmann.org> Tested-by: NJustin P. Mattock <justinmattock@gmail.com> Tested-by: NRoger Quadros <ext-roger.quadros@nokia.com> Tested-by: NMarc Pignat <marc.pignat@hevs.ch>
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