Re: 2.6.14-rc1 wait()/SIG_CHILD bevahiour

[Roland McGrath]

The test program is buggy.  Here is one clue:

	elm3b29:~ # strace -p 30023
	Process 30023 attached - interrupt to quit
	futex(0x2aaaaaddf118, FUTEX_WAIT, 2, NULL

It's not anywhere near wait4.  It's deadlocked in the rand() call inside
rand_delay, called from sigchld_handler.  You cannot safely call rand
inside a signal handler, for exactly this reason.  The signal came during
another rand call and attempted to reenter.  If this sort of deadlock is
the failure mode of your real-world case, then it is probably an
application bug.  If this deadlock is just a mistake in your test program
here, then you'll need to give us a corrected test program to pursue
whatever real kernel issue you may have.


Thanks,
Roland
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