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 01A7BC433EF for ; Mon, 18 Apr 2022 07:11:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234816AbiDRHOL (ORCPT ); Mon, 18 Apr 2022 03:14:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229962AbiDRHOJ (ORCPT ); Mon, 18 Apr 2022 03:14:09 -0400 Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 049E6167E8 for ; Mon, 18 Apr 2022 00:11:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=inria.fr; s=dc; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=mv4SaWQ4Bw/fucJMQTHXYSdAaF06VUODAZIEs7Rd828=; b=lWksnZqipOAWdvIJHQZisQD4gkBg4dI8MjvO0LGlApIsodldzOKpy7RB WkZlN9qNTRdIP0Rz5pZF6HfRrHibnwybDOJS664mmGWq3JP343u7vK3dV W9b500xj2LIBfEoXpNJHkCJmk/9uX5ACczMVJ+EpOgFB8QEErkVJhLi1B s=; Authentication-Results: mail2-relais-roc.national.inria.fr; dkim=none (message not signed) header.i=none; spf=SoftFail smtp.mailfrom=julia.lawall@inria.fr; dmarc=fail (p=none dis=none) d=inria.fr X-IronPort-AV: E=Sophos;i="5.90,269,1643670000"; d="scan'208";a="32129625" Received: from 203.107.68.85.rev.sfr.net (HELO hadrien) ([85.68.107.203]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Apr 2022 09:11:28 +0200 Date: Mon, 18 Apr 2022 09:11:27 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@hadrien To: Alaa Mohamed cc: outreachy@lists.linux.dev, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, ira.weiny@intel.com Subject: Re: [PATCH] xen: gntalloc.c: Convert kmap() to kmap_local_page() In-Reply-To: <20220418061927.6833-1-eng.alaamohamedsoliman.am@gmail.com> Message-ID: References: <20220418061927.6833-1-eng.alaamohamedsoliman.am@gmail.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 18 Apr 2022, Alaa Mohamed wrote: > The use of kmap() is being deprecated in favor of kmap_local_page() > where it is feasible. > > With kmap_local_page(), the mapping is per thread, CPU local and not > globally visible. Therefore __del_gref() is a function > where the use of kmap_local_page() in place of kmap() is correctly > suited. What is it about __del_gref() that makes this change the right choice? julia > > Signed-off-by: Alaa Mohamed > --- > drivers/xen/gntalloc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c > index 4849f94372a4..55acb32842a3 100644 > --- a/drivers/xen/gntalloc.c > +++ b/drivers/xen/gntalloc.c > @@ -178,9 +178,9 @@ static void __del_gref(struct gntalloc_gref *gref) > unsigned long addr; > > if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { > - uint8_t *tmp = kmap(gref->page); > + uint8_t *tmp = kmap_local_page(gref->page); > tmp[gref->notify.pgoff] = 0; > - kunmap(gref->page); > + kunmap_local(tmp); > } > if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { > notify_remote_via_evtchn(gref->notify.event); > -- > 2.35.2 > > >