From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 93C8C375 for ; Wed, 5 Oct 2022 00:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1664930030; x=1696466030; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=EP40TIxfCdK6EWasNHWVWsZEE8ZiilPQNLBOdYuyTFE=; b=iSsAXtdv8QZFrPuzniIU/1iTvkCSo0YRtzCnFpIBiTSTtre4+mdoB+5o WEHh45016E75XO0uSDYWhYttoM1t0UcyA7t7be6EsAXWZ31y9URY5jVJv N5Xh7wAve1weDbDAjmSTtQQrXY+y7eZJ/Z6I7x5eg9+rc9J0OVT5/MwGa TdEOKefoCZjoxuxMjbbCJI15zTyCrqijfc5G1OR2RlmdR0sNOeBfpFUrD lO4PZ8idDtB0lN1ZpCnFFDCSm/OgMoe7nbPrBoNmnndmg8vPQj/cxjna+ l9fCfe4JhlTeCDh18XAgSRXvW0Wa5RiYBs1zApN9ofEylxKJlke+XdAlO A==; X-IronPort-AV: E=McAfee;i="6500,9779,10490"; a="389350954" X-IronPort-AV: E=Sophos;i="5.95,159,1661842800"; d="scan'208";a="389350954" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2022 17:33:49 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10490"; a="799334200" X-IronPort-AV: E=Sophos;i="5.95,159,1661842800"; d="scan'208";a="799334200" Received: from jessicat-mobl.amr.corp.intel.com ([10.209.12.163]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2022 17:33:49 -0700 Date: Tue, 4 Oct 2022 17:33:49 -0700 (PDT) From: Mat Martineau To: Geliang Tang cc: mptcp@lists.linux.dev Subject: Re: [PATCH mptcp-next v4 05/11] mptcp: simplify push_pending In-Reply-To: Message-ID: <171d9a6f-9628-4989-677c-9a6ac38a5880@linux.intel.com> References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed On Sun, 2 Oct 2022, Geliang Tang wrote: > This patch moves the duplicate code from __mptcp_push_pending() and > __mptcp_subflow_push_pending() into a new helper function, named > __subflow_push_pending(). And simplify __mptcp_push_pending() by > invoking this helper. > > Signed-off-by: Geliang Tang > --- > net/mptcp/protocol.c | 90 +++++++++++++++++++++++--------------------- > 1 file changed, 48 insertions(+), 42 deletions(-) > > diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c > index 296b7135e9cf..66c97ac06a4e 100644 > --- a/net/mptcp/protocol.c > +++ b/net/mptcp/protocol.c > @@ -1480,12 +1480,6 @@ struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk) > return ssk; > } > > -static void mptcp_push_release(struct sock *ssk, struct mptcp_sendmsg_info *info) > -{ > - tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, info->size_goal); > - release_sock(ssk); > -} > - > static void mptcp_update_post_push(struct mptcp_sock *msk, > struct mptcp_data_frag *dfrag, > u32 sent) > @@ -1517,6 +1511,52 @@ void mptcp_check_and_set_pending(struct sock *sk) > mptcp_sk(sk)->push_pending |= BIT(MPTCP_PUSH_PENDING); > } > > +static int __subflow_push_pending(struct sock *sk, struct sock *ssk, > + struct mptcp_sendmsg_info *info) > +{ > + struct mptcp_sock *msk = mptcp_sk(sk); > + struct mptcp_data_frag *dfrag; > + int len, copied = 0; > + > + while ((dfrag = mptcp_send_head(sk))) { > + info->sent = dfrag->already_sent; > + info->limit = dfrag->data_len; > + len = dfrag->data_len - dfrag->already_sent; > + while (len > 0) { > + int ret = 0; > + > + ret = mptcp_sendmsg_frag(sk, ssk, dfrag, info); > + if (ret <= 0) { > + if (ret == -EAGAIN) > + continue; In the older code, the scheduler got called again in the -EAGAIN case. With this refactored code, this could get in a very tight loop if mptcp_sendmsg_frag() returns. I think it's necessary to cleanly finish this loop iteration and let the scheduler run again in this -EAGAIN case. > + goto out; > + } > + > + info->sent += ret; > + copied += ret; > + len -= ret; > + > + mptcp_update_post_push(msk, dfrag, ret); > + } > + WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); > + > + if (msk->snd_burst <= 0 || > + !sk_stream_memory_free(ssk) || > + !mptcp_subflow_active(mptcp_subflow_ctx(ssk))) { > + goto out; > + } > + mptcp_set_timeout(sk); > + } > + > +out: > + if (copied) { > + tcp_push(ssk, 0, info->mss_now, tcp_sk(ssk)->nonagle, > + info->size_goal); > + } > + > + return copied; > +} > + > void __mptcp_push_pending(struct sock *sk, unsigned int flags) > { > struct mptcp_sock *msk = mptcp_sk(sk); > @@ -1524,48 +1564,14 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags) > .flags = flags, > }; > bool do_check_data_fin = false; > - struct mptcp_data_frag *dfrag; > struct sock *ssk; > - int len; > > while (mptcp_send_head(sk) && (ssk = mptcp_subflow_get_send(msk))) { > lock_sock(ssk); > - > - while ((dfrag = mptcp_send_head(sk))) { > - info.sent = dfrag->already_sent; > - info.limit = dfrag->data_len; > - len = dfrag->data_len - dfrag->already_sent; > - while (len > 0) { > - int ret = 0; > - > - ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info); > - if (ret <= 0) { > - if (ret == -EAGAIN) > - continue; > - mptcp_push_release(ssk, &info); > - goto out; > - } > - > - do_check_data_fin = true; > - info.sent += ret; > - len -= ret; > - > - mptcp_update_post_push(msk, dfrag, ret); > - } > - WRITE_ONCE(msk->first_pending, mptcp_send_next(sk)); > - > - if (msk->snd_burst <= 0 || > - !sk_stream_memory_free(ssk) || > - !mptcp_subflow_active(mptcp_subflow_ctx(ssk))) { > - goto out; > - } > - mptcp_set_timeout(sk); > - } > - > - mptcp_push_release(ssk, &info); > + do_check_data_fin = __subflow_push_pending(sk, ssk, &info); do_check_data_fin is a bool, but __subflow_push_pending() returns an int (the number of bytes copied). Looking at the other patches, the int value is needed. I suggest assigning the int return value to an int variable: copied = __subflow_push_pending(sk, ssk, &info); and updating the 'if' statement below... > + release_sock(ssk); > } > > -out: > /* ensure the rtx timer is running */ > if (!mptcp_timer_pending(sk)) > mptcp_reset_timer(sk); > if (do_check_data_fin) > __mptcp_check_send_data_fin(sk); ...like this: if (copied > 0) __mptcp_check_send_data_fin(sk); Thanks, -- Mat Martineau Intel