Date: Wed, 9 Oct 2002 19:21:36 -0700 (PDT) From: Don Lewis <dl-freebsd@catspoiler.org> To: e0026813@stud3.tuwien.ac.at Cc: tlambert2@mindspring.com, jhb@FreeBSD.ORG, jmallett@FreeBSD.ORG, current@FreeBSD.ORG, phk@FreeBSD.ORG Subject: Re: [PATCH] Re: Junior Kernel Hacker page updated... Message-ID: <200210100221.g9A2LavU040455@gw.catspoiler.org> In-Reply-To: <20021009225606.GC306@frog.fafoe>
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On 10 Oct, Stefan Farfeleder wrote: > On Tue, Oct 08, 2002 at 09:26:29PM -0700, Don Lewis wrote: >> On 8 Oct, Stefan Farfeleder wrote: >> > However, WITNESS complains (only once) about this: >> > lock order reversal >> > 1st 0xc662140c kqueue mutex (kqueue mutex) @ /freebsd/current/src/sys/kern/kern_event.c:714 >> > 2nd 0xc6727d00 pipe mutex (pipe mutex) @ /freebsd/current/src/sys/kern/sys_pipe.c:1478 >> >> That's pretty similar to the lock order reversal I've seen in the pipe >> code and it's interaction with sigio, which is not suprising since >> pipeselwakeup() calls both pgsigio() and KNOTE(), often while the pipe >> lock is held. Correctly fixing this doesn't look easy ... > > Is it just a warning or does it pose a real problem? It's a warning of a potential problem. If someone else was trying to grab the locks in the opposite order at the same time, you'd get a deadlock. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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