From patchwork Tue Dec 13 17:08:07 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tobias Klausmann X-Patchwork-Id: 9472709 X-Patchwork-Delegate: kvalo@adurom.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B623060760 for ; Tue, 13 Dec 2016 17:10:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B6DFF285CC for ; Tue, 13 Dec 2016 17:10:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AB889285FD; Tue, 13 Dec 2016 17:10:16 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 35EC6285CC for ; Tue, 13 Dec 2016 17:10:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935204AbcLMRJv (ORCPT ); Tue, 13 Dec 2016 12:09:51 -0500 Received: from mout1.fh-giessen.de ([212.201.18.42]:38547 "EHLO mout1.fh-giessen.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935160AbcLMRJm (ORCPT ); Tue, 13 Dec 2016 12:09:42 -0500 Received: from mx2.fh-giessen.de ([212.201.18.41]) by mout1.fh-giessen.de with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1cGqaB-000F5q-Tp; Tue, 13 Dec 2016 18:09:39 +0100 Received: from mailgate-1.its.fh-giessen.de ([212.201.18.15]) by mx2.fh-giessen.de with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1cGqaB-000EzP-Qv; Tue, 13 Dec 2016 18:09:39 +0100 Received: from p549d3380.dip0.t-ipconnect.de ([84.157.51.128] helo=sieben.fritz.box) by mailgate-1.its.fh-giessen.de with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_CBC_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1cGqaB-0007bU-FL; Tue, 13 Dec 2016 18:09:39 +0100 From: Tobias Klausmann To: kvalo@codeaurora.org, helgaas@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, marc.zyngier@arm.com, Janusz.Dziedzic@tieto.com, ath9k-devel@qca.qualcomm.com, linux-wireless@vger.kernel.org, rmanohar@qca.qualcomm.com, bharat.kumar.gogada@xilinx.com Cc: Tobias Klausmann , "# v4 . 9" Subject: [PATCH v2] ath9k: do not return early to fix rcu unlocking Date: Tue, 13 Dec 2016 18:08:07 +0100 Message-Id: <20161213170807.4853-1-tobias.johannes.klausmann@mni.thm.de> X-Mailer: git-send-email 2.11.0 In-Reply-To: References: Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Starting with commit d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible") the driver uses rcu_read_lock() && rcu_read_unlock(), yet on returning early in ath_tx_edma_tasklet() the unlock is missing leading to stalls and suspicious RCU usage: =============================== [ INFO: suspicious RCU usage. ] 4.9.0-rc8 #11 Not tainted ------------------------------- kernel/rcu/tree.c:705 Illegal idle entry in RCU read-side critical section.! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! 1 lock held by swapper/7/0: #0: ( rcu_read_lock ){......} , at: [] ath_tx_edma_tasklet+0x0/0x450 [ath9k] stack backtrace: CPU: 7 PID: 0 Comm: swapper/7 Not tainted 4.9.0-rc8 #11 Hardware name: Acer Aspire V3-571G/VA50_HC_CR, BIOS V2.21 12/16/2013 ffff88025efc3f38 ffffffff8132b1e5 ffff88017ede4540 0000000000000001 ffff88025efc3f68 ffffffff810a25f7 ffff88025efcee60 ffff88017edebdd8 ffff88025eeb5400 0000000000000091 ffff88025efc3f88 ffffffff810c3cd4 Call Trace: [] dump_stack+0x68/0x93 [] lockdep_rcu_suspicious+0xd7/0x110 [] rcu_eqs_enter_common.constprop.85+0x154/0x200 [] rcu_irq_exit+0x44/0xa0 [] irq_exit+0x61/0xd0 [] do_IRQ+0x65/0x110 [] common_interrupt+0x89/0x89 [] ? cpuidle_enter_state+0x151/0x200 [] cpuidle_enter+0x12/0x20 [] call_cpuidle+0x1e/0x40 [] cpu_startup_entry+0x146/0x220 [] start_secondary+0x148/0x170 Signed-off-by: Tobias Klausmann Fixes: d94a461d7a7d ("ath9k: use ieee80211_tx_status_noskb where possible") Cc: # v4.9 Acked-by: Felix Fietkau --- v2: break instead of unlock (rename patch) [Felix Fietkau], fix reference to commit [Kalle Valo] --- drivers/net/wireless/ath/ath9k/xmit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c index 52bfbb988611..e47286bf378e 100644 --- a/drivers/net/wireless/ath/ath9k/xmit.c +++ b/drivers/net/wireless/ath/ath9k/xmit.c @@ -2787,7 +2787,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc) fifo_list = &txq->txq_fifo[txq->txq_tailidx]; if (list_empty(fifo_list)) { ath_txq_unlock(sc, txq); - return; + break; } bf = list_first_entry(fifo_list, struct ath_buf, list);