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=-19.0 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 A8F29C433E6 for ; Wed, 24 Feb 2021 14:25:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5FD4C64EDB for ; Wed, 24 Feb 2021 14:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236536AbhBXOUv (ORCPT ); Wed, 24 Feb 2021 09:20:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:58132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235961AbhBXNIQ (ORCPT ); Wed, 24 Feb 2021 08:08:16 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 603AC64F1A; Wed, 24 Feb 2021 12:54:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614171284; bh=oc9sH3FfW3m1d/SVziZlMlsUu6QxbNnyO4xlIynqzMc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KNlud/HtW7T7Z4f0zLMT2XGnXQ10gqRW4PdlxMDZZp6mbnJnLZswYC7xt1xuCz6H/ oZ3443VsdZZatYAS2n01nOsGCH7xQtpvjMN/LU6wYX37HjhSVLd0BbFMBO6HA25Ku5 HbKAvcc1W+Q40kajCG0dm+OZ/YFgbyfWcKbqZmihxssm5tVWX31tTZ0s9v9DNnO0++ bsYoj8qOVaqTT5n7Rv28GxBOCq+yymoTSzoVfeP25eucCqgE2/rRZx/wc85mMWzXMO JavwUbeb8DIQ3jNLiXpOypz6ryJvXWwSZv79HsFDz5QzZbM3fxCq1/YvNyoAC2BMYh 80nT4ECt2TLmg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miaoqing Pan , Brian Norris , Kalle Valo , Sasha Levin , ath10k@lists.infradead.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 07/26] ath10k: fix wmi mgmt tx queue full due to race condition Date: Wed, 24 Feb 2021 07:54:15 -0500 Message-Id: <20210224125435.483539-7-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210224125435.483539-1-sashal@kernel.org> References: <20210224125435.483539-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miaoqing Pan [ Upstream commit b55379e343a3472c35f4a1245906db5158cab453 ] Failed to transmit wmi management frames: [84977.840894] ath10k_snoc a000000.wifi: wmi mgmt tx queue is full [84977.840913] ath10k_snoc a000000.wifi: failed to transmit packet, dropping: -28 [84977.840924] ath10k_snoc a000000.wifi: failed to submit frame: -28 [84977.840932] ath10k_snoc a000000.wifi: failed to transmit frame: -28 This issue is caused by race condition between skb_dequeue and __skb_queue_tail. The queue of ‘wmi_mgmt_tx_queue’ is protected by a different lock: ar->data_lock vs list->lock, the result is no protection. So when ath10k_mgmt_over_wmi_tx_work() and ath10k_mac_tx_wmi_mgmt() running concurrently on different CPUs, there appear to be a rare corner cases when the queue length is 1, CPUx (skb_deuque) CPUy (__skb_queue_tail) next=list prev=list struct sk_buff *skb = skb_peek(list); WRITE_ONCE(newsk->next, next); WRITE_ONCE(list->qlen, list->qlen - 1);WRITE_ONCE(newsk->prev, prev); next = skb->next; WRITE_ONCE(next->prev, newsk); prev = skb->prev; WRITE_ONCE(prev->next, newsk); skb->next = skb->prev = NULL; list->qlen++; WRITE_ONCE(next->prev, prev); WRITE_ONCE(prev->next, next); If the instruction ‘next = skb->next’ is executed before ‘WRITE_ONCE(prev->next, newsk)’, newsk will be lost, as CPUx get the old ‘next’ pointer, but the length is still added by one. The final result is the length of the queue will reach the maximum value but the queue is empty. So remove ar->data_lock, and use 'skb_queue_tail' instead of '__skb_queue_tail' to prevent the potential race condition. Also switch to use skb_queue_len_lockless, in case we queue a few SKBs simultaneously. Tested-on: WCN3990 hw1.0 SNOC WLAN.HL.3.1.c2-00033-QCAHLSWMTPLZ-1 Signed-off-by: Miaoqing Pan Reviewed-by: Brian Norris Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/1608618887-8857-1-git-send-email-miaoqing@codeaurora.org Signed-off-by: Sasha Levin --- drivers/net/wireless/ath/ath10k/mac.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c index faaca7fe9ad1e..f32d35e03708f 100644 --- a/drivers/net/wireless/ath/ath10k/mac.c +++ b/drivers/net/wireless/ath/ath10k/mac.c @@ -3567,23 +3567,16 @@ bool ath10k_mac_tx_frm_has_freq(struct ath10k *ar) static int ath10k_mac_tx_wmi_mgmt(struct ath10k *ar, struct sk_buff *skb) { struct sk_buff_head *q = &ar->wmi_mgmt_tx_queue; - int ret = 0; - - spin_lock_bh(&ar->data_lock); - if (skb_queue_len(q) == ATH10K_MAX_NUM_MGMT_PENDING) { + if (skb_queue_len_lockless(q) >= ATH10K_MAX_NUM_MGMT_PENDING) { ath10k_warn(ar, "wmi mgmt tx queue is full\n"); - ret = -ENOSPC; - goto unlock; + return -ENOSPC; } - __skb_queue_tail(q, skb); + skb_queue_tail(q, skb); ieee80211_queue_work(ar->hw, &ar->wmi_mgmt_tx_work); -unlock: - spin_unlock_bh(&ar->data_lock); - - return ret; + return 0; } static enum ath10k_mac_tx_path -- 2.27.0