NdisScheduleWorkItem callback function
Note NDIS 5. x has been deprecated and is superseded by NDIS 6. x. For new NDIS driver development, see Network Drivers Starting with Windows Vista. For information about porting NDIS 5. x drivers to NDIS 6. x, see Porting NDIS 5.x Drivers to NDIS 6.0.
NdisScheduleWorkItem inserts a given work item into a queue from which a system worker thread removes the item and gives control to the callback function that the driver previously supplied to NdisInitializeWorkItem.
- WorkItem [in]
Pointer to the work item that was set up by a preceding call to NdisInitializeWorkItem.
NdisScheduleWorkItem always succeeds and therefore always returns NDIS_STATUS_SUCCESS.
A call to NdisScheduleWorkItem allows an NDIS driver to defer some driver-determined operation that could or should be done at a lower IRQL than the raised IRQL at which it is currently running to its worker-thread callback function.
The driver's callback is run within a system thread context at IRQL = PASSIVE_LEVEL later. This caller-supplied function is responsible for reclaiming the storage that the driver allocated for WorkItem. For example, if the driver called NdisAllocateMemoryWithTag to provide a context area to NdisInitializeWorkItem, its callback function should make the reciprocal call to NdisFreeMemory with WorkItem before it returns control.
A driver must not wait for its callback routine to complete an operation if it is already holding one synchronization object and might attempt to acquire another. For example, a NDIS driver should release any currently held spin lock(s), and so forth before it calls NdisScheduleWorkItem. A highest level NDIS protocol driver also must release any currently held semaphores, mutexes, resource variables, and so forth before it calls NdisScheduleWorkItem. Releasing all synchronization resources before queuing a synchronous worker-thread operation prevents deadlocks.
A serialized miniport driver should never attempt to queue a worker-thread callback routine, because there is no way for such a driver to synchronize access to its NIC context area(s) with a worker-thread callback. Consequently, such a serialized NDIS driver cannot share anything in its per-adapter context area with a worker-thread callback function without causing intermittent system crashes.
|Not supported for NDIS 6.0 drivers in Windows Vista. Use NdisQueueIoWorkIteminstead. Supported for NDIS 5.1 drivers in Windows Vista and Windows XP.|