Date: Mon, 13 Sep 2010 15:18:38 -0400 From: John Baldwin <jhb@freebsd.org> To: Matthew D Fleming <mdf@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r212572 - in head/sys: dev/cxgb kern sys vm Message-ID: <201009131518.38829.jhb@freebsd.org> In-Reply-To: <201009131848.o8DImNU6024992@svn.freebsd.org> References: <201009131848.o8DImNU6024992@svn.freebsd.org>
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On Monday, September 13, 2010 2:48:23 pm Matthew D Fleming wrote: > Author: mdf > Date: Mon Sep 13 18:48:23 2010 > New Revision: 212572 > URL: http://svn.freebsd.org/changeset/base/212572 > > Log: > Revert r212370, as it causes a LOR on powerpc. powerpc does a few > unexpected things in copyout(9) and so wiring the user buffer is not > sufficient to perform a copyout(9) while holding a random mutex. > > Requested by: nwhitehorn Hmmm, that is going to break several other sysctls as well then. Many sysctls use sysctl_wire_old_buffer() explicitly so that they can then call SYSCTL_OUT() without dropping a lock. The pcblist sysctls do this for example I think. In general code in the kernel assumes that copyout(9) to/from a wired buffer is safe while holding mutexes or rwlocks. -- John Baldwin
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