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DEVICE_GET_STATE(9)   DragonFly Kernel Developer's Manual  DEVICE_GET_STATE(9)


device_get_state, device_busy, device_unbusy, device_is_alive -- manipulate device state


#include <sys/param.h> #include <sys/bus.h> device_state_t device_get_state(device_t dev); void device_busy(device_t dev); void device_unbusy(device_t dev); int device_is_alive(device_t dev);


The current state of a device is accessed by calling device_get_state() which returns DS_NOTPRESENT, DS_ALIVE, DS_ATTACHED or DS_BUSY (described in device(9)). To test see if a device was successfully probed, call device_is_alive() which simply returns if the state is greater or equal to DS_ALIVE. Each device has a busy count which is incremented when device_busy() is called and decremented when device_unbusy() is called. Both routines return an error if the device state is less than DS_ATTACHED. When device_busy() is called on a device in the DS_ATTACHED state, the device changes to the DS_BUSY state. When device_unbusy() is called and after decrementing, the busy count for the device is zero, the device changes to the DS_ATTACHED state.




This man page was written by Doug Rabson. DragonFly 5.5 June 16, 1998 DragonFly 5.5

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