From owner-cvs-src@FreeBSD.ORG Wed Feb 6 00:37:15 2008 Return-Path: Delivered-To: cvs-src@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2F9EC16A468; Wed, 6 Feb 2008 00:37:15 +0000 (UTC) (envelope-from attilio@FreeBSD.org) Received: from repoman.freebsd.org (repoman.freebsd.org [IPv6:2001:4f8:fff6::29]) by mx1.freebsd.org (Postfix) with ESMTP id 2B35313C4F3; Wed, 6 Feb 2008 00:37:15 +0000 (UTC) (envelope-from attilio@FreeBSD.org) Received: from repoman.freebsd.org (localhost [127.0.0.1]) by repoman.freebsd.org (8.14.1/8.14.1) with ESMTP id m160bF6S030998; Wed, 6 Feb 2008 00:37:15 GMT (envelope-from attilio@repoman.freebsd.org) Received: (from attilio@localhost) by repoman.freebsd.org (8.14.1/8.14.1/Submit) id m160bFNJ030997; Wed, 6 Feb 2008 00:37:15 GMT (envelope-from attilio) Message-Id: <200802060037.m160bFNJ030997@repoman.freebsd.org> From: Attilio Rao Date: Wed, 6 Feb 2008 00:37:15 +0000 (UTC) To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org X-FreeBSD-CVS-Branch: HEAD Cc: Subject: cvs commit: src/sys/kern kern_lock.c src/sys/sys lockmgr.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Feb 2008 00:37:15 -0000 attilio 2008-02-06 00:37:14 UTC FreeBSD src repository Modified files: sys/kern kern_lock.c sys/sys lockmgr.h Log: Add WITNESS support to lockmgr locking primitive. This support tries to be as parallel as possible with other locking primitives, but there are differences; more specifically: - The base witness support is alredy equipped for allowing lock duplication acquisition as lockmgr rely on this. - In the case of lockmgr_disown() the lock result unlocked by witness even if it is still held by the "kernel context" - In the case of upgrading we can have 3 different situations: * Total unlocking of the shared lock and nothing else * Real witness upgrade if the owner is the first upgrader * Shared unlocking and exclusive locking if the owner is not the first upgrade but it is still allowed to upgrade - LK_DRAIN is basically handled like an exclusive acquisition Additively new options LK_NODUP and LK_NOWITNESS can now be used with lockinit(): LK_NOWITNESS disables WITNESS for the specified lock while LK_NODUP enable duplicated locks tracking. This will require manpages update and a __FreeBSD_version bumping (addressed by further commits). This patch also fixes a problem occurring if a lockmgr is held in exclusive mode and the same owner try to acquire it in shared mode: currently there is a spourious shared locking acquisition while what we really want is a lock downgrade. Probabilly, this situation can be better served with a EDEADLK failing errno return. Side note: first testing on this patch alredy reveleated several LORs reported, so please expect LORs cascades until resolved. NTFS also is reported broken by WITNESS introduction. BTW, NTFS is exposing a lock leak which needs to be fixed, and this patch can help it out if rightly tweaked. Tested by: kris, yar, Scot Hetzel Revision Changes Path 1.121 +46 -11 src/sys/kern/kern_lock.c 1.59 +5 -1 src/sys/sys/lockmgr.h