ppoll with multiple threads

ppoll with multiple threads

[Ian Pilcher]

The select(2) man page was updated about a year ago to clarify the
behavior of pselect in multi-threaded programs.

http://git.kernel.org/cgit/docs/man-pages/man-pages.git/commit/man2/select.2?id=2e72e991695f745d6419feeb77598f61d8c86a52

Should a similar update be made to poll(2) for ppoll?

If I'm reading the kernel source (fs/select.c) correctly, both syscalls
(pselect6 and ppoll) use a (possibly unfortunately named) "sigprocmask"
function to manipulate the signal mask, so their behavior should be the
same in this regard.

Also, it might be nice to clarify that these changes are clarifications
of existing behavior, rather than new behavior (i.e. clarify the
clarification).  The current situation is pretty confusing:

http://stackoverflow.com/questions/17011460/ppoll-vs-pselect-with-multiple-threads

-- 
========================================================================
Ian Pilcher                                         arequipeno-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Sometimes there's nothing left to do but crash and burn...or die trying.
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Re: ppoll with multiple threads

[Michael Kerrisk (man-pages)]

Hello Ian,

On 09/27/2013 12:04 AM, Ian Pilcher wrote:
> The select(2) man page was updated about a year ago to clarify the
> behavior of pselect in multi-threaded programs.
> 
> http://git.kernel.org/cgit/docs/man-pages/man-pages.git/commit/man2/select.2?id=2e72e991695f745d6419feeb77598f61d8c86a52
> 
> Should a similar update be made to poll(2) for ppoll?

Yes. Done. And I made the same change in the description of epoll_pwait().

Thanks,

Michael


> If I'm reading the kernel source (fs/select.c) correctly, both syscalls
> (pselect6 and ppoll) use a (possibly unfortunately named) "sigprocmask"
> function to manipulate the signal mask, so their behavior should be the
> same in this regard.
> 
> Also, it might be nice to clarify that these changes are clarifications
> of existing behavior, rather than new behavior (i.e. clarify the
> clarification).  The current situation is pretty confusing:
> 
> http://stackoverflow.com/questions/17011460/ppoll-vs-pselect-with-multiple-threads
> 


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Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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