Date: Sun, 17 Aug 2003 17:12:29 -0400 (EDT)
From: Daniel Eischen <eischen@vigrid.com>
To: Marcel Moolenaar <marcel@xcllnt.net>
Cc: threads@freebsd.org
Subject: Re: First draft: rewrite of {get|set|swap}context(3)
Message-ID: <Pine.GSO.4.10.10308171657400.11196-100000@pcnet5.pcnet.com>
In-Reply-To: <20030817185015.GB928@dhcp42.pn.xcllnt.net>
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On Sun, 17 Aug 2003, Marcel Moolenaar wrote: > Gang, > > Please review the attached patch and let me know to what extend it > introduces breakages. It is the result of "aggressive engineering" > to provoke comments and further fuel discussion. The reason for this > approach is that we currently do not initialize any fields other than > the mcontext and sigmask and only partially copyin() and copyout() > the contexts (typically only the mcontext and sigmask fields). This > generally is very sensitive to breakages, especially when we intro- > duce flags or need to use any of the spare fields. > > getcontext(3): the whole ucontext is zeroed before (partially) filled > and we copyout() all of it. This means that uc_link can only > be set/defined after calling setcontext(). This prevents reuse of the same context without resetting uc_link after every usage. I don't see any requirement by POSIX that uc_link be left intact after getcontext(), but it might be worth preserving... It's up to you. Other than that, the patch looks good. -- Dan Eischen
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