kfifo_from_user (9)

kfifo_from_user(fifo, from, len, copied);

fifo

address of the fifo to be used

from

pointer to the data to be added

len

the length of the data to be added

copied

pointer to output variable to store the number of copied bytes

This macro copies at most len bytes from the from into the fifo, depending of the available space and returns -EFAULT/0.

Note that with only one concurrent reader and one concurrent writer, you don't need extra locking to use these macro.