Re: [PATCH][RFC] Pollable /proc/<pid>/ - avoid SIGCHLD/poll() races

From: Christoph Rohland (cr@sap.com)
Date: Thu Oct 04 2001 - 05:25:36 EST


Hi Paul,

On Thu, 04 Oct 2001, Paul Menage wrote:
>>> The only real user-space solution to this is to have the SIGCHLD
>>> handler somehow cause the select() to return immediately
>>
>>... or implement pselect:
>>http://mesh.eecs.umich.edu/cgi-bin/man2html/usr/share/man/man2/select.2.gz
>
> Agreed, althought that's not a user-space solution. Is there any
> fundamental reason why no-one's implemented pselect()/ppoll() for
> Linux yet?

Missing knowledge and/or demand? It should be pretty easy to
implement.

>>or use sigsetjmp/siglongjmp
>
> Yes, that would probably solve the situation in question, provided
> that siglongjmp() is portably safe. (A comment on LKML in the past
> suggested that it's not safe on cygwin, for example.)

It should be at least portable between different U*X versions. I never
used cygwin though.

Greetings
                Christoph

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