Date: Sun, 23 Jun 2002 18:39:55 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Alfred Perlstein <bright@mu.org>, freebsd-hackers@FreeBSD.ORG, Alan Cox <alc@cs.rice.edu>, Tor.Egge@cvsup.no.freebsd.org Subject: Re: Bug in wakeup() (stable and current) ? Message-ID: <Pine.BSF.4.21.0206231838180.44896-100000@InterJet.elischer.org> In-Reply-To: <200206232032.g5NKWVZW063483@apollo.backplane.com>
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On Sun, 23 Jun 2002, Matthew Dillon wrote: > :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. ummmm Was this found because of my tailq debugging stuff that sets the forward pointer to -1? > > -Matt > Matthew Dillon > <dillon@backplane.com> > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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