From patchwork Tue Mar 15 16:28:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Trond Myklebust X-Patchwork-Id: 12781642 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 58E36C433F5 for ; Tue, 15 Mar 2022 16:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350096AbiCOQfs (ORCPT ); Tue, 15 Mar 2022 12:35:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232897AbiCOQfs (ORCPT ); Tue, 15 Mar 2022 12:35:48 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF71D5005F for ; Tue, 15 Mar 2022 09:34:35 -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 sin.source.kernel.org (Postfix) with ESMTPS id 1B82FCE1BB4 for ; Tue, 15 Mar 2022 16:34:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CA37C340F4 for ; Tue, 15 Mar 2022 16:34:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647362072; bh=uJxKKJu2tEJQPfSUQtoREIBPxxuB+bwNaGc87lg9iaE=; h=From:To:Subject:Date:In-Reply-To:References:From; b=b+AjVT7tQ+3zlfR0J/lHMR41QEkFMhOAc2p1TCJk8wmFR1ZalSnDQYm7HawHC9NEt 1/9CCWJLVxIJJBqSkzcojjr4iYKKjFk2Rcsp1Q2jQ8aNAZuAdb5Fylfez5KiiVbrRh H1RWjqi8/ZIFMUImcPFBLAsgogmLrnbwgXTjoNsMxyqMvX9ThIWIvSgDhTo1unUI7Z a/4UV07YWVnAf6v4W1GOdSVopqupAKqVPxGoGfxaFwl2LcUWOw/mLv+3z1AuVkMPnc m97Wrmc8Sdc6pY88WinwCEaDIvLv5KrVwvl9rmAopPLMHncxnR7eMeFX/nFf0mYQiH psYOHVwz0JxXw== From: trondmy@kernel.org To: linux-nfs@vger.kernel.org Subject: [PATCH 3/3] SUNRPC: Improve accuracy of socket ENOBUFS determination Date: Tue, 15 Mar 2022 12:28:05 -0400 Message-Id: <20220315162805.570850-3-trondmy@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220315162805.570850-2-trondmy@kernel.org> References: <20220315162805.570850-1-trondmy@kernel.org> <20220315162805.570850-2-trondmy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Trond Myklebust The current code checks for whether or not the socket is in a writeable state after we get an EAGAIN. That is racy, since we've dropped the socket lock, so the amount of free buffer may have changed. Instead, let's check whether the socket is writeable before we try to write to it. If that was the case, we do expect the message to be at least partially sent unless we're in a low memory situation. Signed-off-by: Trond Myklebust --- net/sunrpc/xprtsock.c | 53 +++++++++++++++---------------------------- 1 file changed, 18 insertions(+), 35 deletions(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 23cdb841f056..87cc97d6c677 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -805,13 +805,15 @@ static int xs_sock_nospace(struct rpc_rqst *req) return ret; } -static int xs_stream_nospace(struct rpc_rqst *req) +static int xs_stream_nospace(struct rpc_rqst *req, bool vm_wait) { struct sock_xprt *transport = container_of(req->rq_xprt, struct sock_xprt, xprt); struct sock *sk = transport->inet; int ret = -EAGAIN; + if (vm_wait) + return -ENOBUFS; lock_sock(sk); if (!sk_stream_memory_free(sk)) ret = xs_nospace(req, transport); @@ -869,6 +871,7 @@ static int xs_local_send_request(struct rpc_rqst *req) struct msghdr msg = { .msg_flags = XS_SENDMSG_FLAGS, }; + bool vm_wait; unsigned int sent; int status; @@ -881,15 +884,14 @@ static int xs_local_send_request(struct rpc_rqst *req) xs_pktdump("packet data:", req->rq_svec->iov_base, req->rq_svec->iov_len); + vm_wait = sk_stream_is_writeable(transport->inet) ? true : false; + req->rq_xtime = ktime_get(); status = xprt_sock_sendmsg(transport->sock, &msg, xdr, transport->xmit.offset, rm, &sent); dprintk("RPC: %s(%u) = %d\n", __func__, xdr->len - transport->xmit.offset, status); - if (status == -EAGAIN && sock_writeable(transport->inet)) - status = -ENOBUFS; - if (likely(sent > 0) || status == 0) { transport->xmit.offset += sent; req->rq_bytes_sent = transport->xmit.offset; @@ -899,13 +901,12 @@ static int xs_local_send_request(struct rpc_rqst *req) return 0; } status = -EAGAIN; + vm_wait = false; } switch (status) { - case -ENOBUFS: - break; case -EAGAIN: - status = xs_stream_nospace(req); + status = xs_stream_nospace(req, vm_wait); break; default: dprintk("RPC: sendmsg returned unrecognized error %d\n", @@ -1023,7 +1024,7 @@ static int xs_tcp_send_request(struct rpc_rqst *req) struct msghdr msg = { .msg_flags = XS_SENDMSG_FLAGS, }; - bool vm_wait = false; + bool vm_wait; unsigned int sent; int status; @@ -1048,7 +1049,10 @@ static int xs_tcp_send_request(struct rpc_rqst *req) * called sendmsg(). */ req->rq_xtime = ktime_get(); tcp_sock_set_cork(transport->inet, true); - while (1) { + + vm_wait = sk_stream_is_writeable(transport->inet) ? true : false; + + do { status = xprt_sock_sendmsg(transport->sock, &msg, xdr, transport->xmit.offset, rm, &sent); @@ -1069,31 +1073,10 @@ static int xs_tcp_send_request(struct rpc_rqst *req) WARN_ON_ONCE(sent == 0 && status == 0); - if (status == -EAGAIN ) { - /* - * Return EAGAIN if we're sure we're hitting the - * socket send buffer limits. - */ - if (test_bit(SOCK_NOSPACE, &transport->sock->flags)) - break; - /* - * Did we hit a memory allocation failure? - */ - if (sent == 0) { - status = -ENOBUFS; - if (vm_wait) - break; - /* Retry, knowing now that we're below the - * socket send buffer limit - */ - vm_wait = true; - } - continue; - } - if (status < 0) - break; - vm_wait = false; - } + if (sent > 0) + vm_wait = false; + + } while (status == 0); switch (status) { case -ENOTSOCK: @@ -1101,7 +1084,7 @@ static int xs_tcp_send_request(struct rpc_rqst *req) /* Should we call xs_close() here? */ break; case -EAGAIN: - status = xs_stream_nospace(req); + status = xs_stream_nospace(req, vm_wait); break; case -ECONNRESET: case -ECONNREFUSED: