From patchwork Sat Dec 17 16:18:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Leesoo Ahn X-Patchwork-Id: 13075869 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 71FEAC4332F for ; Sat, 17 Dec 2022 16:19:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230081AbiLQQTU (ORCPT ); Sat, 17 Dec 2022 11:19:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229923AbiLQQTS (ORCPT ); Sat, 17 Dec 2022 11:19:18 -0500 Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1FB3FAF6; Sat, 17 Dec 2022 08:19:16 -0800 (PST) Received: by mail-pl1-f172.google.com with SMTP id d15so5153601pls.6; Sat, 17 Dec 2022 08:19:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=YSNNqpsp+6ju7vLQLBaXrvpbttZ9LPvs/Uw4aW9SDeo=; b=yKnJ1awjgn7KUqULVHjdOMU61aIfBRb4WGdZjTCdxp8ck8rSBZIF81dAfhjoTW7A3K xqXyVGXC0IN67kU6PMbPUrk8bnDj6Rb0qhjgrjh/thPCDsnoUYEslDM/kzJlWo88+E5O zZD2VkDT8B5Rz+BDM0p8xNqfB5Yxy6twIAhBxkhzx5Q9OeSE/1Eh6FzY/YdFISwQW3Eb tSOefy5DuDFhn+T51XaeKaEVO993aanRWeDj/MxVlvzva+cJOfvunPZzGzF5lEjRVV3P PBbgynTgf0y0RA29Zl6CHQ54yVJjqZFItxK+sz1Xspl4Rguq1sP9yTBaBd2HFp2LyRBZ 2P5w== X-Gm-Message-State: ANoB5pnJeE7kVWxBIaNd3QiRXX1k1ioYNDUoJtbYBPrb9kWVXK3v/Z6R nLS6iLtUga5X5wAs5vSP4nQ= X-Google-Smtp-Source: AA0mqf6YsrJm/7RjWbwCC3qNvpn+nHnKEMHx5bQ2ETaghl7OzUYaqU1qcV9uyxtABLtljZj/UM5Jog== X-Received: by 2002:a05:6a20:662f:b0:a4:cb41:298f with SMTP id n47-20020a056a20662f00b000a4cb41298fmr32354466pzh.6.1671293956208; Sat, 17 Dec 2022 08:19:16 -0800 (PST) Received: from localhost.localdomain ([14.4.134.166]) by smtp.gmail.com with ESMTPSA id w9-20020a62c709000000b005745635c5b5sm3310513pfg.183.2022.12.17.08.19.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Dec 2022 08:19:15 -0800 (PST) From: Leesoo Ahn To: lsahn@ooseel.net Cc: Oliver Neukum , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] usbnet: jump to rx_cleanup case instead of calling skb_queue_tail Date: Sun, 18 Dec 2022 01:18:51 +0900 Message-Id: <20221217161851.829497-1-lsahn@ooseel.net> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The current source pushes skb into dev->done queue by calling skb_queue_tail() and then, call skb_dequeue() to pop for rx_cleanup state to free urb and skb next in usbnet_bh(). It wastes CPU resource with extra instructions. Instead, use return values jumping to rx_cleanup case directly to free them. Therefore calling skb_queue_tail() and skb_dequeue() is not necessary. The follows are just showing difference between calling skb_queue_tail() and using return values jumping to rx_cleanup state directly in usbnet_bh() in Arm64 instructions with perf tool. ----------- calling skb_queue_tail() ----------- │ if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE)) 7.58 │248: ldr x0, [x20, #16] 2.46 │24c: ldr w0, [x0, #8] 1.64 │250: ↑ tbnz w0, #14, 16c │ dev->net->stats.rx_errors++; 0.57 │254: ldr x1, [x20, #184] 1.64 │258: ldr x0, [x1, #336] 2.65 │25c: add x0, x0, #0x1 │260: str x0, [x1, #336] │ skb_queue_tail(&dev->done, skb); 0.38 │264: mov x1, x19 │268: mov x0, x21 2.27 │26c: → bl skb_queue_tail 0.57 │270: ↑ b 44 // branch to call skb_dequeue() ----------- jumping to rx_cleanup state ----------- │ if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE)) 1.69 │25c: ldr x0, [x21, #16] 4.78 │260: ldr w0, [x0, #8] 3.28 │264: ↑ tbnz w0, #14, e4 // jump to 'rx_cleanup' state │ dev->net->stats.rx_errors++; 0.09 │268: ldr x1, [x21, #184] 2.72 │26c: ldr x0, [x1, #336] 3.37 │270: add x0, x0, #0x1 0.09 │274: str x0, [x1, #336] 0.66 │278: ↑ b e4 // branch to 'rx_cleanup' state Signed-off-by: Leesoo Ahn --- drivers/net/usb/usbnet.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 64a9a80b2309..924392a37297 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -555,7 +555,7 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags) /*-------------------------------------------------------------------------*/ -static inline void rx_process (struct usbnet *dev, struct sk_buff *skb) +static inline int rx_process(struct usbnet *dev, struct sk_buff *skb) { if (dev->driver_info->rx_fixup && !dev->driver_info->rx_fixup (dev, skb)) { @@ -576,11 +576,11 @@ static inline void rx_process (struct usbnet *dev, struct sk_buff *skb) netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len); } else { usbnet_skb_return(dev, skb); - return; + return 0; } done: - skb_queue_tail(&dev->done, skb); + return -1; } /*-------------------------------------------------------------------------*/ @@ -1528,13 +1528,14 @@ static void usbnet_bh (struct timer_list *t) entry = (struct skb_data *) skb->cb; switch (entry->state) { case rx_done: - entry->state = rx_cleanup; - rx_process (dev, skb); + if (rx_process(dev, skb)) + goto cleanup; continue; case tx_done: kfree(entry->urb->sg); fallthrough; case rx_cleanup: +cleanup: usb_free_urb (entry->urb); dev_kfree_skb (skb); continue;