Date: Thu, 10 Dec 1998 22:59:07 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Archie Cobbs <archie@whistle.com> Cc: jwd@unx.sas.com, freebsd-current@FreeBSD.ORG Subject: Re: inetd: realloc/free bug Message-ID: <199812110659.WAA35073@apollo.backplane.com> References: <199812110654.WAA25455@bubba.whistle.com>
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:>
:> If you put a time limit on select(), it doesn't matter if there is a
:> race condition there. How does select() cause a signal to be missed ?
:
:Well, sure.. :-) but then you don't service signals in real time
:and spend extra cycles timing out all the time.
You do serve signals in real time... the signals are *unmasked* during
the select() :-) ... the race condition is that the unmasked signal may
cause the descriptor set to be changed just prior to the select() call,
causing select() to wait forever. The timeout on the select() handles
the race condition without effecting the realtime delivery of signals.
-Matt
:By the way, from man select(2):
:
: BUGS
: select() should probably return the time remaining from the original
: timeout, if any, by modifying the time value in place. This may be im-
: plemented in future versions of the system. Thus, it is unwise to assume
: that the timeout value will be unmodified by the select() call.
:
:Is this ever going to be implemented? I think this warning's been
:around for at least 10 years now..
:
:-Archie
:
:___________________________________________________________________________
:Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com
:
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Matthew Dillon Engineering, HiWay Technologies, Inc. & BEST Internet
Communications & God knows what else.
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