From patchwork Thu Apr 7 06:33:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 561477 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 C93C4C4332F for ; Thu, 7 Apr 2022 06:34:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241165AbiDGGg2 (ORCPT ); Thu, 7 Apr 2022 02:36:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239468AbiDGGgY (ORCPT ); Thu, 7 Apr 2022 02:36:24 -0400 Received: from zju.edu.cn (mail.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 72EDD8B6D8; Wed, 6 Apr 2022 23:34:21 -0700 (PDT) Received: from ubuntu.localdomain (unknown [10.15.192.164]) by mail-app4 (Coremail) with SMTP id cS_KCgBnKRC7hU5imJbiAA--.58581S6; Thu, 07 Apr 2022 14:33:47 +0800 (CST) From: Duoming Zhou To: linux-kernel@vger.kernel.org Cc: chris@zankel.net, jcmvbkbc@gmail.com, mustafa.ismail@intel.com, shiraz.saleem@intel.com, jgg@ziepe.ca, wg@grandegger.com, mkl@pengutronix.de, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, jes@trained-monkey.org, gregkh@linuxfoundation.org, jirislaby@kernel.org, alexander.deucher@amd.com, linux-xtensa@linux-xtensa.org, linux-rdma@vger.kernel.org, linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-hippi@sunsite.dk, linux-staging@lists.linux.dev, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, Duoming Zhou Subject: [PATCH 04/11] drivers: staging: rtl8723bs: Fix deadlock in rtw_surveydone_event_callback() Date: Thu, 7 Apr 2022 14:33:20 +0800 Message-Id: <873d965364c0eec540839dc8ac18fffce997b50c.1649310812.git.duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: X-CM-TRANSID: cS_KCgBnKRC7hU5imJbiAA--.58581S6 X-Coremail-Antispam: 1UD129KBjvJXoW7Cr1Utw17GFWfKryUKrWkCrg_yoW8Xr1xpr 4jgry3KF1jqF1293Wxt3WDWw1fWa1vgFnrJa93Kws5urZ5uF43Zr98tryYqF43ZF9rXwsI yF1kXw15WF45CFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvC1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVWxJr0_GcWl84ACjcxK6I8E 87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c 8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_ Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwI xGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IY c2Ij64vIr41l42xK82IY6x8ErcxFaVAv8VW8uw4UJr1UMxC20s026xCaFVCjc4AY6r1j6r 4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF 67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2I x0cI8IcVCY1x0267AKxVW8Jr0_Cr1UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY 6I8E87Iv67AKxVW8JVWxJwCI42IY6I8E87Iv6xkF7I0E14v26r4UJVWxJrUvcSsGvfC2Kf nxnUUI43ZEXa7VUbXdbUUUUUU== X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgYNAVZdtZEbDgAXsl Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org There is a deadlock in rtw_surveydone_event_callback(), which is shown below: (Thread 1) | (Thread 2) | _set_timer() rtw_surveydone_event_callback()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_scan_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ... We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_surveydone_event_callback() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou --- drivers/staging/rtl8723bs/core/rtw_mlme.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c index ed2d3b7d44d..d559eefe633 100644 --- a/drivers/staging/rtl8723bs/core/rtw_mlme.c +++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c @@ -751,7 +751,9 @@ void rtw_surveydone_event_callback(struct adapter *adapter, u8 *pbuf) } if (check_fwstate(pmlmepriv, _FW_UNDER_SURVEY)) { + spin_unlock_bh(&pmlmepriv->lock); del_timer_sync(&pmlmepriv->scan_to_timer); + spin_lock_bh(&pmlmepriv->lock); _clr_fwstate_(pmlmepriv, _FW_UNDER_SURVEY); }