linux - how to determine whether a function can sleep or not? -

in linux, interrupt handler called top half cannot sleep.

the issue how can determine whether function can cause sleep?

can use input_event, input_sync in top half?

how can determine whether function can cause sleep?

if io-bound operation done, may sleep. doubt specific tool finds whether sleep or not.

can use input_event, input_sync in top half?
got linux documentation uses input_sync in top half. http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/documentation/input/input-programming.txt?id=head