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 6C51CC433F5 for ; Thu, 9 Dec 2021 02:28:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230117AbhLICbm (ORCPT ); Wed, 8 Dec 2021 21:31:42 -0500 Received: from alexa-out-sd-02.qualcomm.com ([199.106.114.39]:33592 "EHLO alexa-out-sd-02.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229909AbhLICbm (ORCPT ); Wed, 8 Dec 2021 21:31:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1639016890; x=1670552890; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=09onxPkSZAaCFE4w/GyZ/nAYG3mvk8lmmMTCNn5pGOM=; b=cbWF3aH38XDaqM96AxFGahxKz1ptTAeWbndCzYXjt1m55t4cQKnJRckM r4d85J3oL1OMR8A0T4455GZzKSedh2/lPLsvT+MJUtn2bu05EZ/CCnhsk zi1HAgd6pbzp9zsXTHCfHFMXZ3QBCiFPYSugsXLEYx9mMedrGBhaDliEZ M=; Received: from unknown (HELO ironmsg03-sd.qualcomm.com) ([10.53.140.143]) by alexa-out-sd-02.qualcomm.com with ESMTP; 08 Dec 2021 18:28:09 -0800 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg03-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Dec 2021 18:28:08 -0800 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Wed, 8 Dec 2021 18:28:08 -0800 Received: from bqiang-Celadon-RN.qca.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Wed, 8 Dec 2021 18:28:07 -0800 From: Baochen Qiang To: CC: Subject: [PATCH] ath11k: Avoid false DEADLOCK warning reported by lockdep Date: Thu, 9 Dec 2021 09:19:49 +0800 Message-ID: <20211209011949.151472-1-quic_bqiang@quicinc.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org With CONFIG_LOCKDEP=y and CONFIG_DEBUG_SPINLOCK=y, lockdep reports below warning: [ 166.059415] ============================================ [ 166.059416] WARNING: possible recursive locking detected [ 166.059418] 5.15.0-wt-ath+ #10 Tainted: G W O [ 166.059420] -------------------------------------------- [ 166.059421] kworker/0:2/116 is trying to acquire lock: [ 166.059423] ffff9905f2083160 (&srng->lock){+.-.}-{2:2}, at: ath11k_hal_reo_cmd_send+0x20/0x490 [ath11k] [ 166.059440] but task is already holding lock: [ 166.059442] ffff9905f2083230 (&srng->lock){+.-.}-{2:2}, at: ath11k_dp_process_reo_status+0x95/0x2d0 [ath11k] [ 166.059491] other info that might help us debug this: [ 166.059492] Possible unsafe locking scenario: [ 166.059493] CPU0 [ 166.059494] ---- [ 166.059495] lock(&srng->lock); [ 166.059498] lock(&srng->lock); [ 166.059500] *** DEADLOCK *** [ 166.059501] May be due to missing lock nesting notation [ 166.059502] 3 locks held by kworker/0:2/116: [ 166.059504] #0: ffff9905c0081548 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1f6/0x660 [ 166.059511] #1: ffff9d2400a5fe68 ((debug_obj_work).work){+.+.}-{0:0}, at: process_one_work+0x1f6/0x660 [ 166.059517] #2: ffff9905f2083230 (&srng->lock){+.-.}-{2:2}, at: ath11k_dp_process_reo_status+0x95/0x2d0 [ath11k] [ 166.059532] stack backtrace: [ 166.059534] CPU: 0 PID: 116 Comm: kworker/0:2 Kdump: loaded Tainted: G W O 5.15.0-wt-ath+ #10 [ 166.059537] Hardware name: Intel(R) Client Systems NUC8i7HVK/NUC8i7HVB, BIOS HNKBLi70.86A.0059.2019.1112.1124 11/12/2019 [ 166.059539] Workqueue: events free_obj_work [ 166.059543] Call Trace: [ 166.059545] [ 166.059547] dump_stack_lvl+0x56/0x7b [ 166.059552] __lock_acquire+0xb9a/0x1a50 [ 166.059556] lock_acquire+0x1e2/0x330 [ 166.059560] ? ath11k_hal_reo_cmd_send+0x20/0x490 [ath11k] [ 166.059571] _raw_spin_lock_bh+0x33/0x70 [ 166.059574] ? ath11k_hal_reo_cmd_send+0x20/0x490 [ath11k] [ 166.059584] ath11k_hal_reo_cmd_send+0x20/0x490 [ath11k] [ 166.059594] ath11k_dp_tx_send_reo_cmd+0x3f/0x130 [ath11k] [ 166.059605] ath11k_dp_rx_tid_del_func+0x221/0x370 [ath11k] [ 166.059618] ath11k_dp_process_reo_status+0x22f/0x2d0 [ath11k] [ 166.059632] ? ath11k_dp_service_srng+0x2ea/0x2f0 [ath11k] [ 166.059643] ath11k_dp_service_srng+0x2ea/0x2f0 [ath11k] [ 166.059655] ath11k_pci_ext_grp_napi_poll+0x1c/0x70 [ath11k_pci] [ 166.059659] __napi_poll+0x28/0x230 [ 166.059664] net_rx_action+0x285/0x310 [ 166.059668] __do_softirq+0xe6/0x4d2 [ 166.059672] irq_exit_rcu+0xd2/0xf0 [ 166.059675] common_interrupt+0xa5/0xc0 [ 166.059678] [ 166.059679] [ 166.059680] asm_common_interrupt+0x1e/0x40 [ 166.059683] RIP: 0010:_raw_spin_unlock_irqrestore+0x38/0x70 [ 166.059686] Code: 83 c7 18 e8 2a 95 43 ff 48 89 ef e8 22 d2 43 ff 81 e3 00 02 00 00 75 25 9c 58 f6 c4 02 75 2d 48 85 db 74 01 fb bf 01 00 00 00 63 2e 40 ff 65 8b 05 8c 59 97 5c 85 c0 74 0a 5b 5d c3 e8 00 6a [ 166.059689] RSP: 0018:ffff9d2400a5fca0 EFLAGS: 00000206 [ 166.059692] RAX: 0000000000000002 RBX: 0000000000000200 RCX: 0000000000000006 [ 166.059694] RDX: 0000000000000000 RSI: ffffffffa404879b RDI: 0000000000000001 [ 166.059696] RBP: ffff9905c0053000 R08: 0000000000000001 R09: 0000000000000001 [ 166.059698] R10: ffff9d2400a5fc50 R11: 0000000000000001 R12: ffffe186c41e2840 [ 166.059700] R13: 0000000000000001 R14: ffff9905c78a1c68 R15: 0000000000000001 [ 166.059704] free_debug_processing+0x257/0x3d0 [ 166.059708] ? free_obj_work+0x1f5/0x250 [ 166.059712] __slab_free+0x374/0x5a0 [ 166.059718] ? kmem_cache_free+0x2e1/0x370 [ 166.059721] ? free_obj_work+0x1f5/0x250 [ 166.059724] kmem_cache_free+0x2e1/0x370 [ 166.059727] free_obj_work+0x1f5/0x250 [ 166.059731] process_one_work+0x28b/0x660 [ 166.059735] ? process_one_work+0x660/0x660 [ 166.059738] worker_thread+0x37/0x390 [ 166.059741] ? process_one_work+0x660/0x660 [ 166.059743] kthread+0x176/0x1a0 [ 166.059746] ? set_kthread_struct+0x40/0x40 [ 166.059749] ret_from_fork+0x22/0x30 [ 166.059754] Since these two lockes are both initialized in ath11k_hal_srng_setup, they are assigned with the same key. As a result lockdep suspects that the task is trying to acquire the same lock (due to same key) while already holding it, and thus reports the DEADLOCK warning. However as they are different spinlock instances, the warning is false positive. On the other hand, even no dead lock indeed, this is a major issue for upstream regression testing as it disables lockdep functionality. Fix it by assigning separate lock class key for each srng->lock. Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1 Signed-off-by: Baochen Qiang --- drivers/net/wireless/ath/ath11k/hal.c | 22 ++++++++++++++++++++++ drivers/net/wireless/ath/ath11k/hal.h | 2 ++ 2 files changed, 24 insertions(+) diff --git a/drivers/net/wireless/ath/ath11k/hal.c b/drivers/net/wireless/ath/ath11k/hal.c index 7cf9e23cb922..2ec09ae90080 100644 --- a/drivers/net/wireless/ath/ath11k/hal.c +++ b/drivers/net/wireless/ath/ath11k/hal.c @@ -974,6 +974,7 @@ int ath11k_hal_srng_setup(struct ath11k_base *ab, enum hal_ring_type type, srng->msi_data = params->msi_data; srng->initialized = 1; spin_lock_init(&srng->lock); + lockdep_set_class(&srng->lock, hal->srng_key + ring_id); for (i = 0; i < HAL_SRNG_NUM_REG_GRP; i++) { srng->hwreg_base[i] = srng_config->reg_start[i] + @@ -1260,6 +1261,24 @@ static int ath11k_hal_srng_create_config(struct ath11k_base *ab) return 0; } +static void ath11k_hal_register_srng_key(struct ath11k_base *ab) +{ + struct ath11k_hal *hal = &ab->hal; + u32 ring_id; + + for (ring_id = 0; ring_id < HAL_SRNG_RING_ID_MAX; ring_id++) + lockdep_register_key(hal->srng_key + ring_id); +} + +static void ath11k_hal_unregister_srng_key(struct ath11k_base *ab) +{ + struct ath11k_hal *hal = &ab->hal; + u32 ring_id; + + for (ring_id = 0; ring_id < HAL_SRNG_RING_ID_MAX; ring_id++) + lockdep_unregister_key(hal->srng_key + ring_id); +} + int ath11k_hal_srng_init(struct ath11k_base *ab) { struct ath11k_hal *hal = &ab->hal; @@ -1279,6 +1298,8 @@ int ath11k_hal_srng_init(struct ath11k_base *ab) if (ret) goto err_free_cont_rdp; + ath11k_hal_register_srng_key(ab); + return 0; err_free_cont_rdp: @@ -1293,6 +1314,7 @@ void ath11k_hal_srng_deinit(struct ath11k_base *ab) { struct ath11k_hal *hal = &ab->hal; + ath11k_hal_unregister_srng_key(ab); ath11k_hal_free_cont_rdp(ab); ath11k_hal_free_cont_wrp(ab); kfree(hal->srng_config); diff --git a/drivers/net/wireless/ath/ath11k/hal.h b/drivers/net/wireless/ath/ath11k/hal.h index 0f4f9ce74354..a7d9b4c551ad 100644 --- a/drivers/net/wireless/ath/ath11k/hal.h +++ b/drivers/net/wireless/ath/ath11k/hal.h @@ -902,6 +902,8 @@ struct ath11k_hal { /* shadow register configuration */ u32 shadow_reg_addr[HAL_SHADOW_NUM_REGS]; int num_shadow_reg_configured; + + struct lock_class_key srng_key[HAL_SRNG_RING_ID_MAX]; }; u32 ath11k_hal_reo_qdesc_size(u32 ba_window_size, u8 tid); -- 2.25.1