From owner-svn-src-head@FreeBSD.ORG Mon Jan 5 17:47:40 2015 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 82662A3C; Mon, 5 Jan 2015 17:47:40 +0000 (UTC) Received: from mail.turbocat.net (mail.turbocat.net [IPv6:2a01:4f8:d16:4514::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 44D823847; Mon, 5 Jan 2015 17:47:40 +0000 (UTC) Received: from laptop015.home.selasky.org (cm-176.74.213.204.customer.telag.net [176.74.213.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.turbocat.net (Postfix) with ESMTPSA id 6B85A1FE022; Mon, 5 Jan 2015 18:47:38 +0100 (CET) Message-ID: <54AACE6A.7020702@selasky.org> Date: Mon, 05 Jan 2015 18:48:26 +0100 From: Hans Petter Selasky User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: John Baldwin , src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r276534 - head/sys/dev/vt References: <201501021335.t02DZBRm015072@svn.freebsd.org> <54AACBC4.5040802@FreeBSD.org> In-Reply-To: <54AACBC4.5040802@FreeBSD.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Jan 2015 17:47:40 -0000 On 01/05/15 18:37, John Baldwin wrote: > On 1/2/15 8:35 AM, Hans Petter Selasky wrote: >> Author: hselasky >> Date: Fri Jan 2 13:35:10 2015 >> New Revision: 276534 >> URL: https://svnweb.freebsd.org/changeset/base/276534 >> >> Log: >> The "vt_suspend_flush_timer()" function is sometimes called locked >> which prevents us from doing a "callout_drain()" call. The callout in >> question has a lock associated with it and we are not freeing the >> callout. That means we can use the "callout_stop()" function to >> atomically stop the callback iff the "callout_stop()" function is >> called locked. This patch applies proper locking to "callout_stop()" >> and replaces a "callout_drain()" with a "callout_stop()". >> >> Modified: head/sys/dev/vt/vt_core.c >> ============================================================================== >> --- head/sys/dev/vt/vt_core.c Fri Jan 2 13:15:36 2015 (r276533) >> +++ head/sys/dev/vt/vt_core.c Fri Jan 2 13:35:10 2015 (r276534) >> @@ -114,6 +114,7 @@ const struct terminal_class vt_termclass >> >> #define VT_LOCK(vd) mtx_lock(&(vd)->vd_lock) >> #define VT_UNLOCK(vd) mtx_unlock(&(vd)->vd_lock) >> +#define VT_LOCK_ASSERT(vd, what) mtx_assert(&(vd)->vd_lock, what) >> >> #define VT_UNIT(vw) ((vw)->vw_device->vd_unit * VT_MAXWINDOWS + \ >> (vw)->vw_number) >> @@ -283,12 +284,18 @@ vt_resume_flush_timer(struct vt_device * >> static void >> vt_suspend_flush_timer(struct vt_device *vd) >> { >> + /* >> + * As long as this function is called locked, callout_stop() >> + * has the same effect like callout_drain() with regard to >> + * preventing the callback function from executing. >> + */ >> + VT_LOCK_ASSERT(vd, MA_OWNED); > > Note that this assert is redundant. callout_stop() already asserts this > for a callout initialized via callout_init_mtx(). > Right, but there is an "if" there which not always makes the assert visible execept for static code analysis. --HPS