centos man page for eventfd_signal

EVENTFD_SIGNAL(9)					  Events based on file descripto					 EVENTFD_SIGNAL(9)

NAME
       eventfd_signal - Adds n to the eventfd counter.

SYNOPSIS
       __u64 eventfd_signal(struct eventfd_ctx * ctx, __u64 n);

ARGUMENTS
       ctx
	   [in] Pointer to the eventfd context.

       n
	   [in] Value of the counter to be added to the eventfd internal counter. The value cannot be negative.

DESCRIPTION
       This function is supposed to be called by the kernel in paths that do not allow sleeping. In this function we allow the counter to reach
       the ULLONG_MAX value, and we signal this as overflow condition by returining a POLLERR to poll(2).

       Returns the amount by which the counter was incrememnted. This will be less than n if the counter has overflowed.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014							 EVENTFD_SIGNAL(9)