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 68AA6C0502A for ; Tue, 30 Aug 2022 08:02:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231371AbiH3ICA (ORCPT ); Tue, 30 Aug 2022 04:02:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229814AbiH3IB5 (ORCPT ); Tue, 30 Aug 2022 04:01:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06EF19D11F; Tue, 30 Aug 2022 01:01:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 94303B81629; Tue, 30 Aug 2022 08:01:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C20E3C433D6; Tue, 30 Aug 2022 08:01:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661846513; bh=ht4Zb7xny/jU85fv7zKRsCxM3zyAR48FezEpPUUfMrg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C0lqN22g0FEIFVPmdUDewu7idrLTy5lvQq1ak0rhRTi1K5PV4hH0Se+i8+pKPeynW kGSlcn0/mSos+bwADVsjUVgE3F1znICkDnst2LdAvMtcpeG6ZpXhERqNiBNHd8lkE1 XjjrytdP2vNgPjhxTZf7A8Pzhhh+7O+vum6rEmYmpe0STVoNGkCJkuNjtzFBvQl4p1 03zVuveOwu0+kIVIK5waxr1t8Ny3BRNOM9Losl+l8MUmD9Gj3VK4HqjDEB5ySWFO9E iqmtPoYEZSUyltFzMGI97om3L6OMADoGHqLE7uGkBe8XZVawJG/zFIPLCEEBf8W5Mj 71Id5ok+Awg0Q== Date: Tue, 30 Aug 2022 11:01:49 +0300 From: Leon Romanovsky To: Jinpu Wang , Christoph Hellwig Cc: jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] RDMA: dma-mapping: Return an unsigned int from ib_dma_map_sg{,_attrs} Message-ID: References: <20220826095615.74328-1-jinpu.wang@ionos.com> <20220826095615.74328-3-jinpu.wang@ionos.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 29, 2022 at 03:19:14PM +0200, Jinpu Wang wrote: > On Mon, Aug 29, 2022 at 2:06 PM Leon Romanovsky wrote: > > > > On Mon, Aug 29, 2022 at 11:40:40AM +0200, Jinpu Wang wrote: > > > On Sun, Aug 28, 2022 at 1:09 PM Leon Romanovsky wrote: > > > > > > > > On Fri, Aug 26, 2022 at 11:56:15AM +0200, Jack Wang wrote: > > > > > Following 2a047e0662ae ("dma-mapping: return an unsigned int from dma_map_sg{,_attrs}") > > > > > change the return value of ib_dma_map_sg{,attrs} to unsigned int. > > > > > > > > > > Cc: Jason Gunthorpe > > > > > Cc: Leon Romanovsky > > > > > Cc: Christoph Hellwig > > > > > Cc: linux-rdma@vger.kernel.org > > > > > Cc: linux-kernel@vger.kernel.org > > > > > > > > > > Signed-off-by: Jack Wang > > > > > --- > > > > > drivers/infiniband/core/device.c | 2 +- > > > > > include/rdma/ib_verbs.h | 6 +++--- > > > > > 2 files changed, 4 insertions(+), 4 deletions(-) > > > > > > > > You forgot to change ib_dma_map_sgtable_attrs() and various > > > > ib_dma_map_sg*() callers. > > > No, they are different. > > > ib_dma_map_sgtable_attrs and dma_map_sgtable return negative on errors. > > > > It is not the point. You changed ib_dma_virt_map_sg() to be unsigned, > > so now the following lines are not correct: > > > > 4138 int nents; > > 4139 > > 4140 if (ib_uses_virt_dma(dev)) { > > 4141 nents = ib_dma_virt_map_sg(dev, sgt->sgl, sgt->orig_nents); > > > > "int nents" should be changed to "unsigned int". > > > > Thanks > ok, I can do it. > just to check if we are on the same page: > For all the callers of ib_dma_map_sg, would it be better to fix it > one patch per driver or do it in a single bigger patch. > I feel it's better to do it per driver, and there are drivers from > different subsystems e.g. nvme/rds/etc. I don't know, everything here looks not nice to me. After commit 2a047e0662ae ("dma-mapping: return an unsigned int from dma_map_sg{,_attrs}"), all callers left in limbo state where they expect that dma_map_sg{,_attrs} will return upto INT_MAX. However now, the API can return upto UINT_MAX, which is not the case now due to internal implementation of dma_map_sg_*(), but can be changed any second. Can we simply revert that commit and restore the "int" return type? I don't see any benefit in having "unsigned int" if compiler doesn't enforce it. Thanks > > Thx! > > > > > > > > > > > > Thanks > > > Thanks!