Date: Wed, 23 Feb 2005 12:38:02 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: Perforce Change Reviews <perforce@FreeBSD.org> Subject: Re: PERFORCE change 71656 for review Message-ID: <200502231238.02637.jhb@FreeBSD.org> In-Reply-To: <200502231158.j1NBwljD042625@repoman.freebsd.org> References: <200502231158.j1NBwljD042625@repoman.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wednesday 23 February 2005 06:58 am, Robert Watson wrote: > http://perforce.freebsd.org/chv.cgi?CH=71656 > > Change 71656 by rwatson@rwatson_paprika on 2005/02/23 11:58:23 > > If oldp is set, sysctl returns the value of a MIB entry before > modification, rather than after. This is kind of wrong. I tried to explain to Tom what should be done but he didn't really get it. The correct order of operations should be this: SYSCTL_IN(&newrule); lock(); oldrule = ...; update(&newrule); unlock(); SYSCTL_OUT(&oldrule); That is, the point is to do the entire read old and write new bit in a single locked section. This more closely matches how most system calls work where they copyin() the arguments, perform actions, then copyout() the results. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200502231238.02637.jhb>