From owner-cvs-src@FreeBSD.ORG Tue Oct 14 14:18:25 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E6DBE16A4BF; Tue, 14 Oct 2003 14:18:25 -0700 (PDT) Received: from mail.pcnet.com (mail.pcnet.com [204.213.232.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id AAE4843F3F; Tue, 14 Oct 2003 14:18:22 -0700 (PDT) (envelope-from eischen@vigrid.com) Received: from mail.pcnet.com (mail.pcnet.com [204.213.232.4]) by mail.pcnet.com (8.12.10/8.12.1) with ESMTP id h9ELIJrq016212; Tue, 14 Oct 2003 17:18:19 -0400 (EDT) Date: Tue, 14 Oct 2003 17:18:19 -0400 (EDT) From: Daniel Eischen X-Sender: eischen@pcnet5.pcnet.com To: John Baldwin In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: Jeff Roberson cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org cc: cvs-src@FreeBSD.org Subject: RE: cvs commit: src/sys/sys mutex.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: deischen@FreeBSD.org List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Oct 2003 21:18:26 -0000 On Tue, 14 Oct 2003, John Baldwin wrote: > > On 14-Oct-2003 Jeff Roberson wrote: > > On Tue, 14 Oct 2003, John Baldwin wrote: > > > >> > >> On 12-Oct-2003 Jeff Roberson wrote: > >> > jeff 2003/10/12 14:02:55 PDT > >> > > >> > FreeBSD src repository > >> > > >> > Modified files: > >> > sys/sys mutex.h > >> > Log: > >> > - Implement a mtx_ownedby() macro which can be used to determine if a > >> > particular thread owns a mutex. This cannot be done without races > >> > unless the thread is curthread. > >> > >> This is a very bad idea. What use do you have for this that is not > >> already handled by mtx_owned() or a mutex assertion? > > > > I know it is racy in most contexts. I use it to check to see if a thread > > on the runq owns giant. Since I have the sched lock it isn't racy but > > even if it was it wouldn't matter in this case. > > sched lock doesn't keep it from being racy. Uncontested acquire and > releases don't go anywhere near sched lock. Are you checking a > non-curthread thread pointer? Maybe you could just do it for curthread > and that would be enough for your heuristic, i.e. > > if (thread == curthread && mtx_owned(&Giant)) { > ... > } > > I'm just worried that if this is there someone is going to use it. :( Just a thought. If you could assign priorities to mutexes (like priority ceiling/protect mutexes), threads owning such mutexes would inherit their priority and the schedulers wouldn't need to know about who owned specific mutexes. -- Dan Eischen