[Bug 20762] New: epoll_wait(2): upper limit to timeout

[bugzilla-daemon-590EEB7GvNiWaY/ihj7yzEB+6BGkLq7r@public.gmane.org]

https://bugzilla.kernel.org/show_bug.cgi?id=20762

           Summary: epoll_wait(2): upper limit to timeout
           Product: Documentation
           Version: unspecified
    Kernel Version: n/a
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: man-pages
        AssignedTo: documentation_man-pages-ztI5WcYan/vQLgFONoPN62D2FQJk+8+b@public.gmane.org
        ReportedBy: arnerup-UNjuZkX4dYU@public.gmane.org
        Regression: No


The timeout argument has an upper limit. Any values above that limit are
treated the same as -1, i.e. to wait indefinitely. The limit is given by:

#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX -
999ULL) / HZ)

That is, the limit depends on the size of a long and the timer frequency.
Assuming the a long is never smaller than 32 bits and HZ never larger than
1000, the worst case is 35 minutes. I think this should be mentioned under
"BUGS".

Although this is likely to be fixed in the future
(http://lkml.org/lkml/2010/8/8/144), the problem exists in at least 2.6.14 -
2.6.35. I don't know if select(2) and poll(2) are affected.

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