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 84D6DC7EE24 for ; Wed, 31 May 2023 08:53:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234975AbjEaIxT (ORCPT ); Wed, 31 May 2023 04:53:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38502 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234938AbjEaIw4 (ORCPT ); Wed, 31 May 2023 04:52:56 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C81E9124 for ; Wed, 31 May 2023 01:52:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685523120; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=WGo4qtRQ4pkJVWaEUVypZ+1I1vSFSgJTj8gN/jNbr24=; b=gdIAnc/w2P6UWFdUZ+zqkF6egz/AAl0gKEF2kl0Q4TIoCpbkLGtzxhvTDz7XQJUI6ebrqR gPnLIrDEj+7UZhnFLys+3qYwmlFHsp5XGAm/cQDGO1HmP2DlHp5XmAAkbfhY9F+4aH1aA5 Uam+Cno+V7OV02Nb36rswnCI0AIsW7s= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-297-6A7MVqTQNyGeS8sO5Uaxog-1; Wed, 31 May 2023 04:51:57 -0400 X-MC-Unique: 6A7MVqTQNyGeS8sO5Uaxog-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CD993280BC41; Wed, 31 May 2023 08:51:56 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9FE4B40E6A43; Wed, 31 May 2023 08:51:54 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20230526201202.1cd35fe9@kernel.org> References: <20230526201202.1cd35fe9@kernel.org> <20230524144923.3623536-1-dhowells@redhat.com> <20230524144923.3623536-4-dhowells@redhat.com> To: Jakub Kicinski Cc: dhowells@redhat.com, netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Paolo Abeni , Willem de Bruijn , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Tom Herbert , Tom Herbert Subject: Re: [PATCH net-next 3/4] kcm: Support MSG_SPLICE_PAGES MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <574369.1685523113.1@warthog.procyon.org.uk> Date: Wed, 31 May 2023 09:51:53 +0100 Message-ID: <574370.1685523113@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jakub Kicinski wrote: > On Wed, 24 May 2023 15:49:22 +0100 David Howells wrote: > > + err = skb_splice_from_iter(skb, &msg->msg_iter, copy, > > + sk->sk_allocation); > > + if (err < 0) { > > + if (err == -EMSGSIZE) > > + goto wait_for_memory; > > + goto out_error; > > + } > > > > should there be a: > > copy = err; > or: > copy -= msg_data_left(msg); > > or some such here? Can we safely assume that skb_splice_from_iter() will > copy all or nothing? Yeah. Good point. I didn't add one because the normal operation code doesn't do that - but I guess that's all-or-nothing. David