Using queued realtime signals in a kernel thread

In a module I'm writing I am trying to do event-driven I/O using queued
realtime signals. Unfortunately, the signals are never sent when data
arrives on a socket that my module is interested in, which makes me think
that I'm not setting things up right. Currently I use this code when my
kernel thread starts:

     sigset_t set;
     sigemptyset(&set);
     sigaddset(&set, signum);
     /* set our blocked mask to set */
     spin_lock_irq(&current->sigmask_lock);
     current->blocked = set;
     spin_unlock_irq(&current->sigmask_lock);

Then when I want to start paying attention to a particular socket, I do
this (all variables have been initialized to sensible values):

     if((err = sys_fcntl(fd, F_SETFL, O_RDWR|O_NONBLOCK|O_NDELAY)) < 0)
          goto out;
     if((err = sys_fcntl(fd, F_SETSIG, signum)) < 0)
          goto out;
     if((err = sys_fcntl(fd, F_SETOWN, current->pid)) < 0)
          goto out;

As far as I can tell, it doesn't work. I've been reading the code, but it's
not helping. Big thanks in advance if anyone wants to lend a clue.

Wesley Felter - [e-mail]
IBM Austin Research Lab