From patchwork Sat Apr 9 01:18:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 12807312 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 F3373C433EF for ; Sat, 9 Apr 2022 01:18:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231299AbiDIBVB (ORCPT ); Fri, 8 Apr 2022 21:21:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229609AbiDIBVA (ORCPT ); Fri, 8 Apr 2022 21:21:00 -0400 Received: from zju.edu.cn (spam.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8CBFA6398; Fri, 8 Apr 2022 18:18:53 -0700 (PDT) Received: from ubuntu.localdomain (unknown [10.15.192.164]) by mail-app2 (Coremail) with SMTP id by_KCgBXj0zz3lBi0_JhAQ--.24619S2; Sat, 09 Apr 2022 09:18:46 +0800 (CST) From: Duoming Zhou To: linux-kernel@vger.kernel.org Cc: linux-rdma@vger.kernel.org, jgg@ziepe.ca, shiraz.saleem@intel.com, mustafa.ismail@intel.com, dan.carpenter@oracle.com, Duoming Zhou Subject: [PATCH V5 09/11] drivers: infiniband: hw: Fix deadlock in irdma_cleanup_cm_core() Date: Sat, 9 Apr 2022 09:18:42 +0800 Message-Id: <20220409011842.45858-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: by_KCgBXj0zz3lBi0_JhAQ--.24619S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Aw13Ar15Xw1rZryxtF43Jrb_yoW8AF4xpr WDW34akryq9F42ka18Xw1kZF9xXwn5XFWqvryvv395ZFn7XFyUAFnFyr1jqFZ8JF9Fgrn3 GF1FvryrCF9Ivr7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkI1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8Jr0_Cr1UM28EF7xvwVC2 z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcV Aq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1j 6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64 vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxAIw28IcxkI7VAKI48JMxAIw28IcVCjz48v 1sIEY20_GFWkJr1UJwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r 18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_JF0_Jw1lIxkGc2Ij64vI r41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr 1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvE x4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7VUbXdbUUUUUU== X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgAPAVZdtZGdgQAUsr Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org There is a deadlock in irdma_cleanup_cm_core(), which is shown below: (Thread 1) | (Thread 2) | irdma_schedule_cm_timer() irdma_cleanup_cm_core() | add_timer() spin_lock_irqsave() //(1) | (wait a time) ... | irdma_cm_timer_tick() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold cm_core->ht_lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need cm_core->ht_lock in position (2) of thread 2. As a result, irdma_cleanup_cm_core() will block forever. This patch removes the check of timer_pending() in irdma_cleanup_cm_core(), because the del_timer_sync() function will just return directly if there isn't a pending timer. As a result, the lock is redundant, because there is no resource it could protect. Signed-off-by: Duoming Zhou --- Changes in V5: - Remove mod_timer() in irdma_schedule_cm_timer and irdma_cm_timer_tick. drivers/infiniband/hw/irdma/cm.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/irdma/cm.c b/drivers/infiniband/hw/irdma/cm.c index dedb3b7edd8..4b6b1065f85 100644 --- a/drivers/infiniband/hw/irdma/cm.c +++ b/drivers/infiniband/hw/irdma/cm.c @@ -3251,10 +3251,7 @@ void irdma_cleanup_cm_core(struct irdma_cm_core *cm_core) if (!cm_core) return; - spin_lock_irqsave(&cm_core->ht_lock, flags); - if (timer_pending(&cm_core->tcp_timer)) - del_timer_sync(&cm_core->tcp_timer); - spin_unlock_irqrestore(&cm_core->ht_lock, flags); + del_timer_sync(&cm_core->tcp_timer); destroy_workqueue(cm_core->event_wq); cm_core->dev->ws_reset(&cm_core->iwdev->vsi);