Daniel Jacobowitz wrote:
> On Thu, Mar 11, 2004 at 01:08:40AM +0000, Michael Snyder wrote:
> 
>>Hey Daniel,
>>
>>Got a question concerning the code in 
>>linux-nat.c::linux_handle_extended_wait.
>>
>>You've got a PTRACE_EVENT_FORK event, and now you're going to call 
>>waitpid.  You pull a pid out of a list of stopped pids, and wait for
>>it using waitpid.  In your comment, you explain that you don't have to
>>worry about the pid being a clone, because you didn't ask for pids in
>>the event mask.
>>
>>But how is this affected by threads, especially NPTL threads?
>>I've got a fairly simple test-case (modified from pthreads.c,
>>I'll attach it), in which a child thread calls fork -- but gdb
>>apparently tries to wait on the main thread (or perhaps the most
>>recent event thread).  Since that's not the thread that called
>>fork, waitpid returns -1 with "no child".  Gdb reports:
>>	waiting for new child: No child processes.
>>
>>FWIW, I've tried this on both a single-processor and an SMP machine.
> 
> 
> No attachment? 

Argh.  Inevitable, isn't it?  See currently attached.

 > Also, what glibc/nptl version are you using.

Well, it's RHEL3, so I believe it's glibc 2.3 and nptl
(not sure what version of nptl).

> It's entirely possible that I didn't handle some threaded case.  But we
> save the PID that we plan to wait on, which should be the child thread,
> so I don't see how what you're describing can happn.

It's repeatable, on at least 3 machines.  Let me know (now that I've
actually provided the test case) if you can't reproduce it.