svn commit: r212572 - in head/sys: dev/cxgb kern sys vm

[John Baldwin]

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