puts some data from user space into the fifo
| fifo, |
| || from, |
| || len, |
| || copied|
address of the fifo to be used
pointer to the data to be added
the length of the data to be added
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.