From owner-svn-src-projects@FreeBSD.ORG Mon Jul 16 00:21:06 2012 Return-Path: Delivered-To: svn-src-projects@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 96D2B1065670; Mon, 16 Jul 2012 00:21:06 +0000 (UTC) (envelope-from davide@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c]) by mx1.freebsd.org (Postfix) with ESMTP id 8203C8FC0C; Mon, 16 Jul 2012 00:21:06 +0000 (UTC) Received: from svn.freebsd.org (localhost [127.0.0.1]) by svn.freebsd.org (8.14.4/8.14.4) with ESMTP id q6G0L643087118; Mon, 16 Jul 2012 00:21:06 GMT (envelope-from davide@svn.freebsd.org) Received: (from davide@localhost) by svn.freebsd.org (8.14.4/8.14.4/Submit) id q6G0L6U6087116; Mon, 16 Jul 2012 00:21:06 GMT (envelope-from davide@svn.freebsd.org) Message-Id: <201207160021.q6G0L6U6087116@svn.freebsd.org> From: Davide Italiano Date: Mon, 16 Jul 2012 00:21:06 +0000 (UTC) To: src-committers@freebsd.org, svn-src-projects@freebsd.org X-SVN-Group: projects MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Subject: svn commit: r238512 - projects/calloutng/sys/kern X-BeenThere: svn-src-projects@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the src " projects" tree" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Jul 2012 00:21:06 -0000 Author: davide Date: Mon Jul 16 00:21:05 2012 New Revision: 238512 URL: http://svn.freebsd.org/changeset/base/238512 Log: Refactor a comment in kern_clocksource.c to explain the need of an apparently duplicate check on event times. Modified: projects/calloutng/sys/kern/kern_clocksource.c Modified: projects/calloutng/sys/kern/kern_clocksource.c ============================================================================== --- projects/calloutng/sys/kern/kern_clocksource.c Mon Jul 16 00:14:25 2012 (r238511) +++ projects/calloutng/sys/kern/kern_clocksource.c Mon Jul 16 00:21:05 2012 (r238512) @@ -871,7 +871,13 @@ cpu_new_callout(int cpu, struct bintime state = DPCPU_ID_PTR(cpu, timerstate); ET_HW_LOCK(state); - /* If there is callout time already set earlier -- do nothing. */ + /* + * If there is callout time already set earlier -- do nothing. + * This check may appear redundant because we check already in + * callout_process() but this double check guarantees we're safe + * with respect to race conditions between interrupts execution + * and scheduling. + */ if (state->nextcall.sec != -1 && bintime_cmp(&bt, &state->nextcall, >=)) { ET_HW_UNLOCK(state);