Date: Fri, 14 Apr 2006 16:14:57 -0400 From: John Baldwin <jhb@freebsd.org> To: src-committers@freebsd.org Cc: cvs-src@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern kern_mutex.c Message-ID: <200604141615.00246.jhb@freebsd.org> In-Reply-To: <200604141951.k3EJpomX069769@repoman.freebsd.org> References: <200604141951.k3EJpomX069769@repoman.freebsd.org>
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On Friday 14 April 2006 15:51, John Baldwin wrote: > jhb 2006-04-14 19:51:50 UTC > > FreeBSD src repository > > Modified files: > sys/kern kern_mutex.c > Log: > Mark the thread pointer used during an adaptive spin volatile so that the > compiler doesn't decide to cache td_state. Cachine the state would cause > the spinning thread to not notice when the owning thread stopped executing > (if it was preempted for example) which could result in livelock. FYI, I've only seen this happen in a local branch, I haven't seen this happen with any CVS kernels. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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