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 X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D4ECC4338F for ; Tue, 24 Aug 2021 17:16:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2384861247 for ; Tue, 24 Aug 2021 17:16:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236407AbhHXRRS (ORCPT ); Tue, 24 Aug 2021 13:17:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:55478 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239582AbhHXROJ (ORCPT ); Tue, 24 Aug 2021 13:14:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E36D961A82; Tue, 24 Aug 2021 17:01:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629824498; bh=gf1OLFyvY3SSmWF2DPapW+nBSDAMwqX1MJHprgYORFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fWPyjB7ncv5OGU5qurtHa0VOOUlGVl2Wzs3o7lr+aC2aRpYtSL4RPfTQHJ5ejxa8Y E1zPot26uYS8ID2Qy0ar67Qz81i1BzeLRpAuSlRDZnUL7zS9nPgHTaYc7q053XvZ3S 7GOV1zYi9hlQDrITf7drF5XJQ57CVKdg5OTZVxUCsw5LvGUB5tTV/9EGwUbbGvYthY XoYUV+Rue6yD1LzUnOL2s3rFCdWuNxpHwY8xTNq5VbNf5dk1jgne1Pma8ViKps6lKk eGoVGnW4llCjJXFKGi6oixNiL+fS4dRBGR/euVQe/iOITslPIgTDmpv+1JlAHiTA3a 8jjywuhZYE1Aw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jakub Kicinski , Michael Chan , Edwin Peer , Sasha Levin Subject: [PATCH 5.4 31/61] bnxt: don't lock the tx queue from napi poll Date: Tue, 24 Aug 2021 13:00:36 -0400 Message-Id: <20210824170106.710221-32-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210824170106.710221-1-sashal@kernel.org> References: <20210824170106.710221-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.4.143-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.4.143-rc1 X-KernelTest-Deadline: 2021-08-26T17:01+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jakub Kicinski [ Upstream commit 3c603136c9f82833813af77185618de5af67676c ] We can't take the tx lock from the napi poll routine, because netpoll can poll napi at any moment, including with the tx lock already held. The tx lock is protecting against two paths - the disable path, and (as Michael points out) the NETDEV_TX_BUSY case which may occur if NAPI completions race with start_xmit and both decide to re-enable the queue. For the disable/ifdown path use synchronize_net() to make sure closing the device does not race we restarting the queues. Annotate accesses to dev_state against data races. For the NAPI cleanup vs start_xmit path - appropriate barriers are already in place in the main spot where Tx queue is stopped but we need to do the same careful dance in the TX_BUSY case. Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.") Reviewed-by: Michael Chan Reviewed-by: Edwin Peer Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 54 ++++++++++++++--------- 1 file changed, 32 insertions(+), 22 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c index 287ea792922a..8111aefb2411 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -360,6 +360,26 @@ static u16 bnxt_xmit_get_cfa_action(struct sk_buff *skb) return md_dst->u.port_info.port_id; } +static bool bnxt_txr_netif_try_stop_queue(struct bnxt *bp, + struct bnxt_tx_ring_info *txr, + struct netdev_queue *txq) +{ + netif_tx_stop_queue(txq); + + /* netif_tx_stop_queue() must be done before checking + * tx index in bnxt_tx_avail() below, because in + * bnxt_tx_int(), we update tx index before checking for + * netif_tx_queue_stopped(). + */ + smp_mb(); + if (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh) { + netif_tx_wake_queue(txq); + return false; + } + + return true; +} + static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct bnxt *bp = netdev_priv(dev); @@ -387,8 +407,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) free_size = bnxt_tx_avail(bp, txr); if (unlikely(free_size < skb_shinfo(skb)->nr_frags + 2)) { - netif_tx_stop_queue(txq); - return NETDEV_TX_BUSY; + if (bnxt_txr_netif_try_stop_queue(bp, txr, txq)) + return NETDEV_TX_BUSY; } length = skb->len; @@ -597,16 +617,7 @@ tx_done: if (netdev_xmit_more() && !tx_buf->is_push) bnxt_db_write(bp, &txr->tx_db, prod); - netif_tx_stop_queue(txq); - - /* netif_tx_stop_queue() must be done before checking - * tx index in bnxt_tx_avail() below, because in - * bnxt_tx_int(), we update tx index before checking for - * netif_tx_queue_stopped(). - */ - smp_mb(); - if (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh) - netif_tx_wake_queue(txq); + bnxt_txr_netif_try_stop_queue(bp, txr, txq); } return NETDEV_TX_OK; @@ -690,14 +701,9 @@ next_tx_int: smp_mb(); if (unlikely(netif_tx_queue_stopped(txq)) && - (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh)) { - __netif_tx_lock(txq, smp_processor_id()); - if (netif_tx_queue_stopped(txq) && - bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh && - txr->dev_state != BNXT_DEV_STATE_CLOSING) - netif_tx_wake_queue(txq); - __netif_tx_unlock(txq); - } + bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh && + READ_ONCE(txr->dev_state) != BNXT_DEV_STATE_CLOSING) + netif_tx_wake_queue(txq); } static struct page *__bnxt_alloc_rx_page(struct bnxt *bp, dma_addr_t *mapping, @@ -8371,9 +8377,11 @@ void bnxt_tx_disable(struct bnxt *bp) if (bp->tx_ring) { for (i = 0; i < bp->tx_nr_rings; i++) { txr = &bp->tx_ring[i]; - txr->dev_state = BNXT_DEV_STATE_CLOSING; + WRITE_ONCE(txr->dev_state, BNXT_DEV_STATE_CLOSING); } } + /* Make sure napi polls see @dev_state change */ + synchronize_net(); /* Drop carrier first to prevent TX timeout */ netif_carrier_off(bp->dev); /* Stop all TX queues */ @@ -8387,8 +8395,10 @@ void bnxt_tx_enable(struct bnxt *bp) for (i = 0; i < bp->tx_nr_rings; i++) { txr = &bp->tx_ring[i]; - txr->dev_state = 0; + WRITE_ONCE(txr->dev_state, 0); } + /* Make sure napi polls see @dev_state change */ + synchronize_net(); netif_tx_wake_all_queues(bp->dev); if (bp->link_info.link_up) netif_carrier_on(bp->dev); -- 2.30.2