From patchwork Mon Oct 20 15:27:07 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andre Detsch X-Patchwork-Id: 5075 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id ED0A8DE03A for ; Tue, 21 Oct 2008 02:27:17 +1100 (EST) X-Original-To: cbe-oss-dev@ozlabs.org Delivered-To: cbe-oss-dev@ozlabs.org Received: from igw2.br.ibm.com (igw2.br.ibm.com [32.104.18.25]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mailgw2.br.ibm.com", Issuer "Equifax" (not verified)) by ozlabs.org (Postfix) with ESMTPS id C9024DDDEC; Tue, 21 Oct 2008 02:27:00 +1100 (EST) Received: from d24relay01.br.ibm.com (unknown [9.8.31.16]) by igw2.br.ibm.com (Postfix) with ESMTP id 0F31D17F495; Mon, 20 Oct 2008 13:26:07 -0200 (BRDT) Received: from d24av02.br.ibm.com (d24av02.br.ibm.com [9.18.232.47]) by d24relay01.br.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m9KFQgqC2572334; Mon, 20 Oct 2008 12:26:42 -0300 Received: from d24av02.br.ibm.com (loopback [127.0.0.1]) by d24av02.br.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m9KFQux0007188; Mon, 20 Oct 2008 13:26:56 -0200 Received: from [9.18.196.237] ([9.18.196.237]) by d24av02.br.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id m9KFQteF007142; Mon, 20 Oct 2008 13:26:56 -0200 From: Andre Detsch To: Jeremy Kerr , cbe-oss-dev@ozlabs.org Date: Mon, 20 Oct 2008 13:27:07 -0200 User-Agent: KMail/1.9.6 MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200810201327.07179.adetsch@br.ibm.com> Cc: krafft@linux.vnet.ibm.com Subject: [Cbe-oss-dev] [PATCH] powerpc/spufs: explain conditional decrement of aff_sched_count X-BeenThere: cbe-oss-dev@ozlabs.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Discussion about Open Source Software for the Cell Broadband Engine List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cbe-oss-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org Errors-To: cbe-oss-dev-bounces+patchwork-incoming=ozlabs.org@ozlabs.org This patch adds a comment to clarify why atomic_dec_if_positive is being used to decrement gang's aff_sched_count on SPU context unbind. Signed-off-by: Andre Detsch Index: spufs/arch/powerpc/platforms/cell/spufs/sched.c =================================================================== --- spufs.orig/arch/powerpc/platforms/cell/spufs/sched.c +++ spufs/arch/powerpc/platforms/cell/spufs/sched.c @@ -437,6 +437,11 @@ static void spu_unbind_context(struct sp atomic_dec(&cbe_spu_info[spu->node].reserved_spus); if (ctx->gang) + /* + * If ctx->gang->aff_sched_count is positive, SPU affinity is + * being considered in this gang. Using atomic_dec_if_positive + * allow us to skip an explicit check for affinity in this gang + */ atomic_dec_if_positive(&ctx->gang->aff_sched_count); spu_switch_notify(spu, NULL);