From owner-svn-src-all@FreeBSD.ORG Sat Oct 3 15:02:55 2009 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 56A4B1065693; Sat, 3 Oct 2009 15:02:55 +0000 (UTC) (envelope-from attilio@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 457E18FC08; Sat, 3 Oct 2009 15:02:55 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id n93F2thT043969; Sat, 3 Oct 2009 15:02:55 GMT (envelope-from attilio@svn.freebsd.org) Received: (from attilio@localhost) by svn.freebsd.org (8.14.3/8.14.3/Submit) id n93F2tOp043967; Sat, 3 Oct 2009 15:02:55 GMT (envelope-from attilio@svn.freebsd.org) Message-Id: <200910031502.n93F2tOp043967@svn.freebsd.org> From: Attilio Rao Date: Sat, 3 Oct 2009 15:02:55 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r197735 - head/sys/kern X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 03 Oct 2009 15:02:55 -0000 Author: attilio Date: Sat Oct 3 15:02:55 2009 New Revision: 197735 URL: http://svn.freebsd.org/changeset/base/197735 Log: When releasing a lockmgr held in shared way we need to use a write memory barrier in order to avoid, on architectures which doesn't have strong ordered writes, CPU instructions reordering. Diagnosed by: fabio Modified: head/sys/kern/kern_lock.c Modified: head/sys/kern/kern_lock.c ============================================================================== --- head/sys/kern/kern_lock.c Sat Oct 3 14:38:22 2009 (r197734) +++ head/sys/kern/kern_lock.c Sat Oct 3 15:02:55 2009 (r197735) @@ -241,7 +241,7 @@ wakeupshlk(struct lock *lk, const char * * and return. */ if (LK_SHARERS(x) > 1) { - if (atomic_cmpset_ptr(&lk->lk_lock, x, + if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, x - LK_ONE_SHARER)) break; continue; @@ -254,7 +254,7 @@ wakeupshlk(struct lock *lk, const char * if ((x & LK_ALL_WAITERS) == 0) { MPASS((x & ~LK_EXCLUSIVE_SPINNERS) == LK_SHARERS_LOCK(1)); - if (atomic_cmpset_ptr(&lk->lk_lock, x, LK_UNLOCKED)) + if (atomic_cmpset_rel_ptr(&lk->lk_lock, x, LK_UNLOCKED)) break; continue; } @@ -280,7 +280,7 @@ wakeupshlk(struct lock *lk, const char * queue = SQ_SHARED_QUEUE; } - if (!atomic_cmpset_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x, + if (!atomic_cmpset_rel_ptr(&lk->lk_lock, LK_SHARERS_LOCK(1) | x, v)) { sleepq_release(&lk->lock_object); continue;