Bug 14001 - eventfd manpage missing EFD_SEMAPHORE flag
Summary: eventfd manpage missing EFD_SEMAPHORE flag
Status: RESOLVED CODE_FIX
Alias: None
Product: Documentation
Classification: Unclassified
Component: man-pages (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: documentation_man-pages@kernel-bugs.osdl.org
URL:
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Depends on:
Blocks:
 
Reported: 2009-08-18 05:38 UTC by Anton Blanchard
Modified: 2010-08-30 14:25 UTC (History)
1 user (show)

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Regression: No
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Description Anton Blanchard 2009-08-18 05:38:38 UTC 
I noticed eventfd added a new flag, EFD_SEMAPHORE which isn't documented
in the git manpages tree:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=bcd0b235bf3808dec5115c381cd55568f63b85f0
Comment 1 Michael Kerrisk 2010-08-30 05:29:50 UTC 
For man-pages-3.26, I added this text:

       EFD_SEMAPHORE (since Linux 2.6.30)
              Provide semaphore-like semantics  for  reads  from
              the new file descriptor.  See below.
...
              *  If EFD_SEMAPHORE  was  not  specified  and  the
                 eventfd  counter  has  a  nonzero value, then a
                 read(2) returns 8 bytes containing that  value,
                 and the counter's value is reset to zero.

              *  If  EFD_SEMAPHORE was specified and the eventfd
                 counter has a nonzero  value,  then  a  read(2)
                 returns 8 bytes containing the value 1, and the
                 counter's value is decremented by 1.
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