Well, I'm back. I didn't get any help from the uClibc folks, but I eventually figured out how to get to the waitid function in the kernel using the _syscall4 macro and the right header file. waitid worked great, but then I started having problems when more than one child needed to be reaped.
Basically, the parent process registers a SIGCHLD signal handler via sigaction() with the SA_RESTART option and then sits on a timed select(). All the signal handler does is set a flag - the waitid processing takes place when the parent drops out of the select because of the signal or a timeout. When the waitid succeeds, the pid is used to do some processing and then is used to call waitpid to clean up the mess. This is all in a while loop, so when the waitid is called again, 0 is returned with si_pid = 0 indicating that there are no more children to reap. That's all great. The problem occurs when there's 2 or more children to reap. When this occurs, the 2nd waitid call returns -1 and si_pid = 0. The waitid continues to fail in this manner until the parent receives another SIGCHLD signal, then it works for the next zombie child in the waiting line, but only one. I can send SIGCHLD kills to the parent from the console and eventually get everything cleaned up. Sending the kill from the parent isn't enough - I suppose it wants to be blocking on the select. I tried registering the signal handler without SA_RESRART and also via signal(), since there was a posting about SA_RESTART, but that made no difference. I also tried not having a signal handler at all, but then I couldn't reap any children on the timeout. So, are there known issues with waitid when there are multiple children piled up waiting to be reaped? If so, is there a patch or a workaround? The product that I'm working on is using Linux version 2.6.12-2.0.0-258 Thanks for any help, Sue On 1/18/07, James Chapman <[EMAIL PROTECTED]> wrote:
You're asking the wrong list. Try the uClibc list at uclibc.org. glibc and uClibc provide C APIs to kernel system calls. uClibc doesn't implement all features that glibc supports - there are several kernel APIs that uClibc doesn't expose. Ask the uClibc folk for advice. -- James Chapman Katalix Systems Ltd http://www.katalix.com Catalysts for your Embedded Linux software development
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