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[35.245.174.172]) by smtp.gmail.com with ESMTPSA id m17-20020a0cf191000000b00631ecb1052esm1216204qvl.74.2023.06.20.05.59.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jun 2023 05:59:19 -0700 (PDT) Date: Tue, 20 Jun 2023 08:59:18 -0400 From: Willem de Bruijn To: David Howells , Willem de Bruijn Cc: dhowells@redhat.com, netdev@vger.kernel.org, Alexander Duyck , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , David Ahern , Matthew Wilcox , Jens Axboe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, dccp@vger.kernel.org, linux-afs@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-can@vger.kernel.org, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-hams@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-rdma@vger.kernel.org, linux-sctp@vger.kernel.org, linux-wpan@vger.kernel.org, linux-x25@vger.kernel.org, mptcp@lists.linux.dev, rds-devel@oss.oracle.com, tipc-discussion@lists.sourceforge.net, virtualization@lists.linux-foundation.org Message-ID: <6491a2a6f1488_3bcfec294d7@willemb.c.googlers.com.notmuch> In-Reply-To: <784658.1687176327@warthog.procyon.org.uk> References: <648f36d02fe6e_33cfbc2944f@willemb.c.googlers.com.notmuch> <20230617121146.716077-1-dhowells@redhat.com> <20230617121146.716077-18-dhowells@redhat.com> <784658.1687176327@warthog.procyon.org.uk> Subject: Re: [PATCH net-next v2 17/17] net: Kill MSG_SENDPAGE_NOTLAST Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: C56931C001A X-Stat-Signature: wczj4e4roxqkk14oi55j9sy1xk83y47h X-HE-Tag: 1687265960-908458 X-HE-Meta: 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 /6V8IAPr 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: David Howells wrote: > Willem de Bruijn wrote: > > > Is it intentional to add MSG_MORE here in this patch? > > > > I do see that patch 3 removes this branch: > > Yeah. I think I may have tcp_bpf a bit wrong with regard to handling > MSG_MORE. > > How about the attached version of tcp_bpf_push()? > > I wonder if it's save to move the setting of MSG_SENDPAGE_NOPOLICY out of the > loop as I've done here. The caller holds the socket lock. > > Also, I'm not sure whether to take account of apply/apply_bytes when setting > MSG_MORE mid-message, or whether to just go on whether we've reached > sge->length yet. (I'm not sure exactly how tcp_bpf works). I'm not very familiar with it either. Instead of inferring whether MSG_MORE is safe to set, as below, sufficient to rely on the caller to pass it when appropriate? size = min(apply_bytes, sge->length). I doubt that size < apply_bytes is ever intended. And instead of this former branch if (flags & MSG_SENDPAGE_NOTLAST) msghdr.msg_flags |= MSG_MORE; update any caller to pass MSG_MORE instead of MSG_SENDPAGE_NOTLAST, if not yet done so. > msghdr.msg_flags = flags; > > /* Determine if we need to set MSG_MORE. */ > if (!(msghdr.msg_flags & MSG_MORE)) { > if (apply && size < apply_bytes) > msghdr.msg_flags |= MSG_MORE; > else if (!apply && size < sge->length && > msg->sg.start != msg->sg.end) > msghdr.msg_flags |= MSG_MORE; > }