From owner-svn-src-head@freebsd.org Fri Feb 26 02:26:21 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 07F09AB431C; Fri, 26 Feb 2016 02:26:21 +0000 (UTC) (envelope-from sephe@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (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 C7DCE15C0; Fri, 26 Feb 2016 02:26:20 +0000 (UTC) (envelope-from sephe@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id u1Q2QJHn079624; Fri, 26 Feb 2016 02:26:19 GMT (envelope-from sephe@FreeBSD.org) Received: (from sephe@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id u1Q2QJZG079623; Fri, 26 Feb 2016 02:26:19 GMT (envelope-from sephe@FreeBSD.org) Message-Id: <201602260226.u1Q2QJZG079623@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: sephe set sender to sephe@FreeBSD.org using -f From: Sepherosa Ziehau Date: Fri, 26 Feb 2016 02:26:19 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r296076 - head/sys/dev/hyperv/vmbus X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.20 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: Fri, 26 Feb 2016 02:26:21 -0000 Author: sephe Date: Fri Feb 26 02:26:19 2016 New Revision: 296076 URL: https://svnweb.freebsd.org/changeset/base/296076 Log: hyperv: Use atomic_fetchadd_int to get GPADL id. Reviewed by: Hongjiang Zhang MFC after: 1 week Sponsored by: Microsoft OSTC Differential Revision: https://reviews.freebsd.org/D5439 Modified: head/sys/dev/hyperv/vmbus/hv_channel.c Modified: head/sys/dev/hyperv/vmbus/hv_channel.c ============================================================================== --- head/sys/dev/hyperv/vmbus/hv_channel.c Fri Feb 26 01:52:33 2016 (r296075) +++ head/sys/dev/hyperv/vmbus/hv_channel.c Fri Feb 26 02:26:19 2016 (r296076) @@ -384,17 +384,22 @@ hv_vmbus_channel_establish_gpadl( hv_vmbus_channel_msg_info* curr; uint32_t next_gpadl_handle; - next_gpadl_handle = hv_vmbus_g_connection.next_gpadl_handle; - atomic_add_int((int*) &hv_vmbus_g_connection.next_gpadl_handle, 1); + next_gpadl_handle = atomic_fetchadd_int( + &hv_vmbus_g_connection.next_gpadl_handle, 1); ret = vmbus_channel_create_gpadl_header( contig_buffer, size, &msg_info, &msg_count); - if(ret != 0) { /* if(allocation failed) return immediately */ - /* reverse atomic_add_int above */ - atomic_subtract_int((int*) - &hv_vmbus_g_connection.next_gpadl_handle, 1); - return ret; + if(ret != 0) { + /* + * XXX + * We can _not_ even revert the above incremental, + * if multiple GPADL establishments are running + * parallelly, decrement the global next_gpadl_handle + * is calling for _big_ trouble. A better solution + * is to have a 0-based GPADL id bitmap ... + */ + return ret; } sema_init(&msg_info->wait_sema, 0, "Open Info Sema");