Re: [gpsd-dev] [PATCH] Use pselect() to reduce wakeups and avoid race conditions

[Håkan Johansson]

Regarding (p)select and signal races, I did not see the 'self-pipe trick' 
mentioned in the discussion.  Quoting 
http://www.kernel.org/doc/man-pages/online/pages/man2/select.2.html:

"On systems that lack pselect(), reliable (and more portable) signal 
trapping can be achieved using the self-pipe trick (where a signal handler 
writes a byte to a pipe whose other end is monitored by select() in the 
main program.)"

This fixed a similar problem for me once.  There was no select, just 
reads, but the race was locking a data acquisition system up when bad 
luck struck.

Cheers,
Håkan