From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34363C433EF for ; Wed, 20 Jul 2022 04:42:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238594AbiGTEmR (ORCPT ); Wed, 20 Jul 2022 00:42:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235726AbiGTEmK (ORCPT ); Wed, 20 Jul 2022 00:42:10 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A8BA4D826 for ; Tue, 19 Jul 2022 21:42:08 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id s18-20020a17090aa11200b001f1e9e2438cso923416pjp.2 for ; Tue, 19 Jul 2022 21:42:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=z6PUXTFpSe4hiCUpV3CY8funZOBFDw7H3e5Gt/0oRi8=; b=IiA+Q3w7zcBZOjHNflXfuaDtcS0ofGYGJgJWsq4Cf7CP0tR6FSimksTaqsZ9RVrCvo hVQl0Sxm4Qmk/1Wh+8uoKT2FQfORQnp3GvzPZL4n4zE6VpagMTb7V5Wh0Qouy9+dsKRb pdIqK2s6JusvHaXj6WCdei7BHZbhFbNhZcdZV4BgLbv8rkJwTaBgmKqfL8ati8gMD/hz 0fwQghDnWZbUKuL6JStZQEaPokRjdWQI/PXd+/aCan+fkymViXTxaCvTjO57CcU5HkuS OvRcoq6NbtIvCJD3fSA967WLAIYtbsHHkAI2Z8OgBhg5X0oaw5jQS0xkU5ruzaZLWIT2 zvnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=z6PUXTFpSe4hiCUpV3CY8funZOBFDw7H3e5Gt/0oRi8=; b=ti+O8qcsBUHfcLqGG+X4ukakL0xNPJRRFIiXysD+s6WIaRENcizB7oHS5MsVO9v81y yYyZOSjh7IKJQaazyikTfu57VuH7o4xAuTcH56+FaLJ87KZ3aEKmGnVMV6QYYwCqW5CR LmtOLtl9ikiKBEsGgF+O0KKtkWTvVDaeI92DCJe/eAI6v/MK3PCtWz1mBmKKpbLyc7yM RvE0siJcRi8ta7BkAHxhknfgkVNlHgdxh4z1EA2NwMhRSvrBJH1rebkLHbepTiGwAwLr t+TsRYUJLY2l/2nluXiXEorl1IcGx7s+NeVElTXcDdt2CE3J8Z2ovybzaMYR0xAXrh1U 5JCg== X-Gm-Message-State: AJIora/CjAUBbRuteOo+XC7f9HUG9UgpUuOi3eZf7ThvZUoeGXv/XFbW Ynue+ZBB0flPjBv+2TGOKMQA X-Google-Smtp-Source: AGRyM1tt91KBDyuERAEmvcgNVxEzq6JDq55QvVpRznWDCgI3BajGSlbzGAniss0JVswRpX8Scw0Pmg== X-Received: by 2002:a17:90b:3c0c:b0:1ef:e647:ff48 with SMTP id pb12-20020a17090b3c0c00b001efe647ff48mr3189743pjb.173.1658292128063; Tue, 19 Jul 2022 21:42:08 -0700 (PDT) Received: from localhost ([139.177.225.253]) by smtp.gmail.com with ESMTPSA id r16-20020aa79890000000b005254e44b748sm12303495pfl.84.2022.07.19.21.42.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jul 2022 21:42:07 -0700 (PDT) From: Xie Yongji To: mst@redhat.com, jasowang@redhat.com, xiaodong.liu@intel.com, maxime.coquelin@redhat.com, stefanha@redhat.com Cc: songmuchun@bytedance.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/5] vduse: Remove unnecessary spin lock protection Date: Wed, 20 Jul 2022 12:41:40 +0800 Message-Id: <20220720044144.90-2-xieyongji@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220720044144.90-1-xieyongji@bytedance.com> References: <20220720044144.90-1-xieyongji@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now we use domain->iotlb_lock to protect two different variables: domain->bounce_maps->bounce_page and domain->iotlb. But for domain->bounce_maps->bounce_page, we actually don't need any synchronization between vduse_domain_get_bounce_page() and vduse_domain_free_bounce_pages() since vduse_domain_get_bounce_page() will only be called in page fault handler and vduse_domain_free_bounce_pages() will be called during file release. So let's remove the unnecessary spin lock protection in vduse_domain_get_bounce_page(). Then the usage of domain->iotlb_lock could be more clear: the lock will be only used to protect the domain->iotlb. Signed-off-by: Xie Yongji --- drivers/vdpa/vdpa_user/iova_domain.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c index 6daa3978d290..bca1f0b8850c 100644 --- a/drivers/vdpa/vdpa_user/iova_domain.c +++ b/drivers/vdpa/vdpa_user/iova_domain.c @@ -211,17 +211,14 @@ static struct page * vduse_domain_get_bounce_page(struct vduse_iova_domain *domain, u64 iova) { struct vduse_bounce_map *map; - struct page *page = NULL; + struct page *page; - spin_lock(&domain->iotlb_lock); map = &domain->bounce_maps[iova >> PAGE_SHIFT]; if (!map->bounce_page) - goto out; + return NULL; page = map->bounce_page; get_page(page); -out: - spin_unlock(&domain->iotlb_lock); return page; } -- 2.20.1