Man page 9 : kfifo_in

kfifo_in - put data into the fifo

kfifo_in( fifo , buf , n );

fifo
    address of the fifo to be used

buf
    the data to be added

n
    number of elements to be added

This macro copies the given buffer into the fifo and returns the number of copied elements.

Note that with only one concurrent reader and one concurrent writer, you donAqt need extra locking to use these macro.