ieee80211_rx_irqsafe can be
called in hardware interrupt context. The low-level driver must not call any
other functions in hardware interrupt context. If there is a need for such
call, the low-level driver should first ACK the interrupt and perform the
IEEE 802.11 code call after this, e.g. from a scheduled workqueue or even
NOTE: If the driver opts to use the
_irqsafe functions, it may not also
use the non-IRQ-safe functions!