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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AC6CC4332F for ; Mon, 14 Nov 2022 13:08:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237866AbiKNNI1 (ORCPT ); Mon, 14 Nov 2022 08:08:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237868AbiKNNI0 (ORCPT ); Mon, 14 Nov 2022 08:08:26 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2B4C82AE12 for ; Mon, 14 Nov 2022 05:08:20 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id BC24761173 for ; Mon, 14 Nov 2022 13:08:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFD16C433D6; Mon, 14 Nov 2022 13:08:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1668431299; bh=1Le296MTu+nDrcM+GOOjQ4YMT0Od1j/6jGpnPSFBaLs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=krDTtWJNnacQ5Xq4b9dQHLGZK3ZjS0VI7iwBYnV3OKoy6k+2ie/KrOGUYdBv3kGK7 QAeTSP62Mib/L9W+IvV19SdR5FYCs/V6ZrM/7DU1U7bRKj/lOc0iq3bxDa+S+lV7uY YSDOlFJMP77Je/B+o9U7s7887jyiwpbSFfaXYWYk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wen Gong , Kalle Valo Subject: [PATCH 6.0 145/190] wifi: ath11k: avoid deadlock during regulatory update in ath11k_regd_update() Date: Mon, 14 Nov 2022 13:46:09 +0100 Message-Id: <20221114124505.136943532@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221114124458.806324402@linuxfoundation.org> References: <20221114124458.806324402@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Wen Gong commit f45cb6b29cd36514e13f7519770873d8c0457008 upstream. (cherry picked from commit d99884ad9e3673a12879bc2830f6e5a66cccbd78 in ath-next as users are seeing this bug more now, also cc stable) Running this test in a loop it is easy to reproduce an rtnl deadlock: iw reg set FI ifconfig wlan0 down What happens is that thread A (workqueue) tries to update the regulatory: try to acquire the rtnl_lock of ar->regd_update_work rtnl_lock+0x17/0x20 ath11k_regd_update+0x15a/0x260 [ath11k] ath11k_regd_update_work+0x15/0x20 [ath11k] process_one_work+0x228/0x670 worker_thread+0x4d/0x440 kthread+0x16d/0x1b0 ret_from_fork+0x22/0x30 And thread B (ifconfig) tries to stop the interface: try to cancel_work_sync(&ar->regd_update_work) in ath11k_mac_op_stop(). ifconfig 3109 [003] 2414.232506: probe: ath11k_mac_op_stop: (ffffffffc14187a0) drv_stop+0x30 ([mac80211]) ieee80211_do_stop+0x5d2 ([mac80211]) ieee80211_stop+0x3e ([mac80211]) __dev_close_many+0x9e ([kernel.kallsyms]) __dev_change_flags+0xbe ([kernel.kallsyms]) dev_change_flags+0x23 ([kernel.kallsyms]) devinet_ioctl+0x5e3 ([kernel.kallsyms]) inet_ioctl+0x197 ([kernel.kallsyms]) sock_do_ioctl+0x4d ([kernel.kallsyms]) sock_ioctl+0x264 ([kernel.kallsyms]) __x64_sys_ioctl+0x92 ([kernel.kallsyms]) do_syscall_64+0x3a ([kernel.kallsyms]) entry_SYSCALL_64_after_hwframe+0x63 ([kernel.kallsyms]) __GI___ioctl+0x7 (/lib/x86_64-linux-gnu/libc-2.23.so) The sequence of deadlock is: 1. Thread B calls rtnl_lock(). 2. Thread A starts to run and calls rtnl_lock() from within ath11k_regd_update_work(), then enters wait state because the lock is owned by thread B. 3. Thread B continues to run and tries to call cancel_work_sync(&ar->regd_update_work), but thread A is in ath11k_regd_update_work() waiting for rtnl_lock(). So cancel_work_sync() forever waits for ath11k_regd_update_work() to finish and we have a deadlock. Fix this by switching from using regulatory_set_wiphy_regd_sync() to regulatory_set_wiphy_regd(). Now cfg80211 will schedule another workqueue which handles the locking on it's own. So the ath11k workqueue can simply exit without taking any locks, avoiding the deadlock. Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3 Cc: Signed-off-by: Wen Gong [kvalo: improve commit log] Signed-off-by: Kalle Valo Signed-off-by: Greg Kroah-Hartman --- drivers/net/wireless/ath/ath11k/reg.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) --- a/drivers/net/wireless/ath/ath11k/reg.c +++ b/drivers/net/wireless/ath/ath11k/reg.c @@ -287,11 +287,7 @@ int ath11k_regd_update(struct ath11k *ar goto err; } - rtnl_lock(); - wiphy_lock(ar->hw->wiphy); - ret = regulatory_set_wiphy_regd_sync(ar->hw->wiphy, regd_copy); - wiphy_unlock(ar->hw->wiphy); - rtnl_unlock(); + ret = regulatory_set_wiphy_regd(ar->hw->wiphy, regd_copy); kfree(regd_copy);