Date: Sun, 23 Jun 2002 13:32:31 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Alfred Perlstein <bright@mu.org> Cc: freebsd-hackers@FreeBSD.ORG, Julian Elischer <julian@elischer.org>, Alan Cox <alc@cs.rice.edu>, Tor.Egge@cvsup.no.freebsd.org Subject: Re: Bug in wakeup() (stable and current) ? Message-ID: <200206232032.g5NKWVZW063483@apollo.backplane.com> References: <200206232014.g5NKE5x3058562@apollo.backplane.com> <20020623201933.GM53232@elvis.mu.org>
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:I'm pretty sure you only need to 'goto restart' if you call into
:maybe_resched() as someone else may have manipulated the queues.
:
:The 'restart' label is only in there for restarting in case one of
:the functions called may change the lists, if we restart _every_
:time we'll traverse the same procs where p->p_wchan != ident over
:and over needlessly.
:
:-Alfred
Look at the code carefully. It's *removing* the element from the list,
the conditionally restarting rather then removing the element from the
list and unconditionally restarting. The only reason it works at all
is because sys/queue.h does not clear out the pointers in the node
that was just removed. The code is just plain wrong, though, because
the queue mechanisms make no such (documented) guarentee.
-Matt
Matthew Dillon
<dillon@backplane.com>
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