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 X-Spam-Level: X-Spam-Status: No, score=-21.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A427FC433ED for ; Mon, 5 Apr 2021 12:40:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 708376138A for ; Mon, 5 Apr 2021 12:40:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235409AbhDEMkH (ORCPT ); Mon, 5 Apr 2021 08:40:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:43486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235289AbhDEMkH (ORCPT ); Mon, 5 Apr 2021 08:40:07 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 50024613A3; Mon, 5 Apr 2021 12:40:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617626401; bh=EnYc02ojerZa0n6Tf2F3o1fHFoGaCmzd1tnTjO9i5Y0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VFBfCZLPjVa9HU9psssGoSfKq2tPp1iuQVskIbIlGBQhYnTiucMc8CKZGCv5CIuWB 2NQgXWX7P+eDi4V0MWFPJCs6dDXBodc66h8CohHYcMp4KqG2XZKf7RHqEm+iNViy3Y 1tyGOu8eSzlmdkgqDx3lSytTknONEGF75w3z8vxmEyBqIURu0yGQD63D91qVJxi/hw U9Hh2KEpZSBR98MFm2OSl/6s/8xzhzkyhc+/JGsb65YpoY/wLI6VjkeTNUjXYe9GOj fI7GWTKG4l20T8YcZ1A3Qq055AUpTibNUOUdD8CWhKAeQ0+6iWkZUZMpCZHbGNt/4b xZpMwtA1Us4+Q== Date: Mon, 5 Apr 2021 15:39:57 +0300 From: Leon Romanovsky To: Gal Pressman Cc: Jason Gunthorpe , Doug Ledford , linux-rdma@vger.kernel.org, Alexander Matushevsky , Yossi Leybovich , Jason Gunthorpe Subject: Re: [PATCH for-next] RDMA/nldev: Add copy-on-fork attribute to get sys command Message-ID: References: <20210405114722.98904-1-galpress@amazon.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-rdma@vger.kernel.org On Mon, Apr 05, 2021 at 03:15:18PM +0300, Gal Pressman wrote: > On 05/04/2021 14:57, Leon Romanovsky wrote: > > On Mon, Apr 05, 2021 at 02:47:21PM +0300, Gal Pressman wrote: > >> The new attribute indicates that the kernel copies DMA pages on fork, > >> hence libibverbs' fork support through madvise and MADV_DONTFORK is not > >> needed. > >> > >> The introduced attribute is always reported as supported since the > >> kernel has the patch that added the copy-on-fork behavior. This allows > >> the userspace library to identify older vs newer kernel versions. > >> Extra care should be taken when backporting this patch as it relies on > >> the fact that the copy-on-fork patch is merged, hence no check for > >> support is added. > > > > Please be more specific, add SHA-1 of that patch and wrote the same > > comment near "err = nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK, > > 1);" line. > > > > Thanks > > Should I put the original commit here? There were quite a lot of bug fixes and > followups that are required. IMHO, the last commit SHA will be enough, the one that has working functionality from your POV. Thanks > > >> > >> Copy-on-fork attribute is read-only, trying to change it through the set > >> sys command will result in an error. > >> > >> Signed-off-by: Gal Pressman > >> --- > >> PR was sent: > >> https://github.com/linux-rdma/rdma-core/pull/975 > >> --- > >> drivers/infiniband/core/nldev.c | 19 ++++++++++++++----- > >> include/uapi/rdma/rdma_netlink.h | 2 ++ > >> 2 files changed, 16 insertions(+), 5 deletions(-) > >> > >> diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c > >> index b8dc002a2478..87c68301c25b 100644 > >> --- a/drivers/infiniband/core/nldev.c > >> +++ b/drivers/infiniband/core/nldev.c > >> @@ -146,6 +146,7 @@ static const struct nla_policy nldev_policy[RDMA_NLDEV_ATTR_MAX] = { > >> [RDMA_NLDEV_ATTR_UVERBS_DRIVER_ID] = { .type = NLA_U32 }, > >> [RDMA_NLDEV_NET_NS_FD] = { .type = NLA_U32 }, > >> [RDMA_NLDEV_SYS_ATTR_NETNS_MODE] = { .type = NLA_U8 }, > >> + [RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK] = { .type = NLA_U8 }, > >> }; > >> > >> static int put_driver_name_print_type(struct sk_buff *msg, const char *name, > >> @@ -1693,12 +1694,19 @@ static int nldev_sys_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh, > >> > >> err = nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_NETNS_MODE, > >> (u8)ib_devices_shared_netns); > >> - if (err) { > >> - nlmsg_free(msg); > >> - return err; > >> - } > >> + if (err) > >> + goto err_nlmsg_free; > >> + > >> + err = nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK, 1); > >> + if (err) > >> + goto err_nlmsg_free; > > > > Is it important to have an ability to fail here? Can we simply ignore > > failure? > > Should be fine. > > Thanks