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From: vandys@hpindda.HP.COM (Andy Valencia)
Newsgroups: comp.unix.microport
Subject: Re: Trouble killing processes in SysV/AT
Message-ID: <7030006@hpindda.HP.COM>
Date: 29 Apr 88 15:44:26 GMT
References: <3951@killer.UUCP>
Organization: HP Technical Networks, Cupertino, Calif.
Lines: 12


	A "classic" way to make an unkillable process is to have it
block on an I/O device which isn't going to finish its I/O.  The trick
is that if it sleep()s with a certain priority or above, signals will
unblock it (and thus you get interruptible system calls), but if it's
below, then signals can't get to the process until it unblocks.  Now
all you need is for some I/O operation to get frozen (say, lose an
interrupt, or mishandle it), and you have the unkillable process.

			We are having fun now, ja?
			Andy Valencia
			vandys%hpindda.UUCP@hplabs.hp.com