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,USER_AGENT_GIT autolearn=ham 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 8A193C4320A for ; Wed, 11 Aug 2021 19:32:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C7036109F for ; Wed, 11 Aug 2021 19:32:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231585AbhHKTdG (ORCPT ); Wed, 11 Aug 2021 15:33:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:37264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231154AbhHKTdF (ORCPT ); Wed, 11 Aug 2021 15:33:05 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E55AC60E78; Wed, 11 Aug 2021 19:32:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628710361; bh=zZ4jSUjQIOnj/gEHEf9S+GTyogRCKb06WhYWjacd4WA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HwpDaSLi78PlcUKNSyQGraTW1lfQBQlcZ4rn11mgjyNid93sUquPZr9bFnFw/H1KM Mlwqu0gFuZApDkFWNtuc2aFXsOXS5qTj4pboTcICmo6N/LiBUDvbK/tGXIy7R4/Y20 6rwpLye82nNNJc9dqWK8lhvU/b3Sj82COa0cbuleWYhQktgTg8yDKM5XrKUhKatH1F J3l/LXzj7XUlNmPlcGmaVdm6ojn7K9N2nqlroYoeBtWdoqtW2i/95qPGlslZ3+rSPb BOe3b0DlQivi2ulEiEI3bHpH0SKwmXNbEzsv5i2FfxtyD8nQpmX6Utl+txMzIHT7hM 9Fu5XCb8vv9mw== From: Jakub Kicinski To: davem@davemloft.net Cc: michael.chan@broadcom.com, huangjw@broadcom.com, eddie.wai@broadcom.com, prashant@broadcom.com, gospo@broadcom.com, netdev@vger.kernel.org, edwin.peer@broadcom.com, Jakub Kicinski Subject: [PATCH net 1/4] bnxt: don't lock the tx queue from napi poll Date: Wed, 11 Aug 2021 12:32:36 -0700 Message-Id: <20210811193239.3155396-2-kuba@kernel.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210811193239.3155396-1-kuba@kernel.org> References: <20210811193239.3155396-1-kuba@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. It seems that the tx lock is only protecting against the disable path, appropriate barriers are already in place to make sure cleanup can safely run concurrently with start_xmit. I don't see any other reason why 'stopped && avail > thresh' needs to be re-checked under the lock. Remove the tx lock and use synchronize_net() to make sure closing the device does not race we restarting the queues. Annotate accesses to dev_state against data races. Fixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.") Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c index 865fcb8cf29f..07827d6b0fec 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -730,15 +730,10 @@ static void bnxt_tx_int(struct bnxt *bp, struct bnxt_napi *bnapi, int nr_pkts) */ 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); - } + if (netif_tx_queue_stopped(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, @@ -9264,9 +9259,11 @@ 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 */ @@ -9280,8 +9277,10 @@ 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); -- 2.31.1