ifnet Struct Reference

Detailed Description

Structure defining a network interface.

ifnet and its related packet queues are protected by if_serializer. Callers of if_output, if_ioctl, if_start, if_watchdog, if_init, if_resolvemulti, and if_poll hold if_serializer. Device drivers usually use the same serializer for their interrupt but this is not required. However, the device driver must be holding if_serializer when it calls if_input. Note that the serializer may be temporarily released within if_input to avoid a deadlock (e.g. when fast-forwarding or bridging packets between interfaces).

If a device driver installs the same serializer for its interrupt as for ifnet, then the driver only really needs to worry about further serialization in timeout based entry points. All other entry points will already be serialized. Older ISA drivers still using the old interrupt infrastructure will have to obtain and release the serializer in their interrupt routine themselves.