From owner-freebsd-hackers Sun Jun 23 16:47:18 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by hub.freebsd.org (Postfix) with ESMTP id 33CF337B401 for ; Sun, 23 Jun 2002 16:47:15 -0700 (PDT) Received: by elvis.mu.org (Postfix, from userid 1192) id DED44AE147; Sun, 23 Jun 2002 16:47:14 -0700 (PDT) Date: Sun, 23 Jun 2002 16:47:14 -0700 From: Alfred Perlstein To: Matthew Dillon Cc: freebsd-hackers@FreeBSD.ORG, Julian Elischer , Alan Cox , Tor.Egge@cvsup.no.freebsd.org Subject: Re: Bug in wakeup() (stable and current) ? Message-ID: <20020623234714.GN53232@elvis.mu.org> References: <200206232014.g5NKE5x3058562@apollo.backplane.com> <20020623201933.GM53232@elvis.mu.org> <200206232032.g5NKWVZW063483@apollo.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200206232032.g5NKWVZW063483@apollo.backplane.com> User-Agent: Mutt/1.3.27i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG * Matthew Dillon [020623 13:32] 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 ------^^^ then?? > 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. You're right, but other than await() why would a process find itself on a sleep queue if not in SSLEEP? -- -Alfred Perlstein [alfred@freebsd.org] 'Instead of asking why a piece of software is using "1970s technology," start asking why software is ignoring 30 years of accumulated wisdom.' Tax deductible donations for FreeBSD: http://www.freebsdfoundation.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message