Man page 9 : kfifo_out

kfifo_out - get data from the fifo

kfifo_out( fifo , buf , n );

fifo
    address of the fifo to be used

buf
    pointer to the storage buffer

n
    max. number of elements to get

This macro get some data from the fifo and return the numbers of elements copied.

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