Date: Thu, 15 Sep 2005 14:35:40 +0800 From: Ariff Abdullah <skywizard@MyBSD.org.my> To: pyunyh@gmail.com, minimarmot@gmail.com Cc: freebsd-current@freebsd.org Subject: Re: panic upon kldunload snd_ich (lor # 159) Message-ID: <20050915143540.72b66996.skywizard@MyBSD.org.my> In-Reply-To: <20050915043448.GB18332@rndsoft.co.kr> References: <47d0403c05091121047a037946@mail.gmail.com> <20050912044212.GC5182@rndsoft.co.kr> <47d0403c05091122276fd0a231@mail.gmail.com> <20050913070149.GE9481@rndsoft.co.kr> <47d0403c0509131235ed58122@mail.gmail.com> <20050914014830.GA13631@rndsoft.co.kr> <20050915033848.2d87da42.skywizard@MyBSD.org.my> <20050915014509.GA17602@rndsoft.co.kr> <20050915114653.431f17c5.skywizard@MyBSD.org.my> <20050915043448.GB18332@rndsoft.co.kr>
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On Thu, 15 Sep 2005 13:34:48 +0900 Pyun YongHyeon <pyunyh@gmail.com> wrote: > On Thu, Sep 15, 2005 at 11:46:53AM +0800, Ariff Abdullah wrote: > > On Thu, 15 Sep 2005 10:45:09 +0900 > > Pyun YongHyeon <pyunyh@gmail.com> wrote: > > > > > > That would be supposed to fix the LOR message. But I'd like to > > > keep lock ordering between snd_mutex and sndstat_lock. Since > > > sndstat_read() could be called at any time there is an implicit > > > lock order. I think switching to sx lock from mutex in sndstat > > > code was to allow uiomove with lock held. IMO, it would be even > > > better to rewrite sndstat_read() without using uiomove such that > > > it can also use standard mutex rather than sx lock. > > > > > I tend to agree with you. Since that sndstat_busy() isn't enough, > > how about we acquire the entire sndstat so nobody can monkey with > > it (as the proposed / attached diff) and at the same time avoiding > > this LOR message. It seems much better rather than locking sndstat > > after sndstat_busy() and much of pcm_unregister() procedures, only > > to find out that somebody acquire it within that moment. > > > > I didn't try the patch but it looks good to me. :-) > If you have more time would you please fix race in sndstat_open()? > > Minor note : I think it is better to use sx_xunlock ranther than > sx_unlock as sx_xunlock clearly indicates which type of locks held. > o my, that was a mass typo. Will fix it. -- Ariff Abdullah MyBSD http://www.MyBSD.org.my (IPv6/IPv4) http://staff.MyBSD.org.my (IPv6/IPv4) http://tomoyo.MyBSD.org.my (IPv6/IPv4)
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