Date: Thu, 05 Feb 1998 21:48:42 +1030 From: Mike Smith <mike@smith.net.au> To: Graham Wheeler <gram@cdsec.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Shared memory and signals Message-ID: <199802051118.VAA00292@word.smith.net.au> In-Reply-To: Your message of "Sat, 02 Feb 1998 17:41:35 %2B0200." <199802021541.RAA07701@cdsec.com>
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> I was wondering whether it is safe to call shmdt and shmctl from within > a signal handler. I have a program which forks off child processes which > communicate their results back using a shared memory segment. I would like > the parent to detach and release the shared memory from within the SIGCHLD > signal handler, but I'm not sure whether this is safe. Can you do this more cleanly by calling wait4? Unless you are sleeping on something inside the segment, I can't *think* of any reentrancy/ locking issues, but I would be worried about the locking you'd have to apply around the other datastructures that your handler might be accessing. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\
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