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Fri, 30 Aug 2024 02:39:15 GMT Received: from bqiang-SFF.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 15.2.1544.9; Thu, 29 Aug 2024 19:39:13 -0700 From: Baochen Qiang To: CC: , Subject: [PATCH] wifi: ath12k: avoid deadlock during regulatory update in ath12k_regd_update() Date: Fri, 30 Aug 2024 10:39:01 +0800 Message-ID: <20240830023901.204746-1-quic_bqiang@quicinc.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: YhfKptEDqQEDr26b0iQrx08Kipm9iax2 X-Proofpoint-ORIG-GUID: YhfKptEDqQEDr26b0iQrx08Kipm9iax2 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-08-29_06,2024-08-29_02,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 suspectscore=0 lowpriorityscore=0 malwarescore=0 spamscore=0 mlxlogscore=999 mlxscore=0 bulkscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2408300018 From: Wen Gong 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 ath12k_regd_update [ath12k] ath12k_regd_update_work [ath12k] process_one_work worker_thread kthread ret_from_fork And thread B (ifconfig) tries to stop the interface: try to cancel_work_sync(&ar->regd_update_work) in ath12k_mac_op_stop(). ifconfig 3109 [003] 2414.232506: probe: ath12k_mac_op_stop [ath12k] drv_stop [mac80211] ieee80211_do_stop [mac80211] ieee80211_stop [mac80211] The sequence of deadlock is: 1. Thread B calls rtnl_lock(). 2. Thread A starts to run and calls rtnl_lock() from within ath12k_regd_update_work(), then enters wait state because the lock is owned by thread B. 3. Thread B tries to call cancel_work_sync(&ar->regd_update_work), but thread A is in ath12k_regd_update_work() waiting for rtnl_lock(). So cancel_work_sync() forever waits for ath12k_regd_update_work() to finish and we have a deadlock. Change to use regulatory_set_wiphy_regd(), which is the asynchronous version of regulatory_set_wiphy_regd_sync(). This way rtnl & wiphy locks are not required so can be removed, and in the end the deadlock issue can be avoided. But a side effect introduced by the asynchronous regd update is that, some essential information used in ath12k_reg_update_chan_list(), which would be called later in ath12k_regd_update(), might has not been updated by cfg80211, as a result wrong channel parameters sent to firmware. To handle this side effect, move ath12k_reg_update_chan_list() to ath12k_reg_notifier(), and advertise WIPHY_FLAG_NOTIFY_REGDOM_BY_DRIVER to cfg80211. This works because, in the process of the asynchronous regd update, after the new regd is processed, cfg80211 will notify ath12k by calling ath12k_reg_notifier(). Since all essential information is updated at that time, we are good to do channel list update. Please note ath12k_reg_notifier() could also be called due to other reasons, like core/beacon/user hints etc. For them we are not allowed to call ath12k_reg_update_chan_list() because regd has not been updated. This is done by verifying the initiator. Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3 Signed-off-by: Wen Gong Co-developed-by: Baochen Qiang Signed-off-by: Baochen Qiang Acked-by: Jeff Johnson --- drivers/net/wireless/ath/ath12k/reg.c | 35 +++++++++++++++------------ 1 file changed, 20 insertions(+), 15 deletions(-) base-commit: 8fb3b2b8d6d489416a7ff8a28cd4083340ad9e55 diff --git a/drivers/net/wireless/ath/ath12k/reg.c b/drivers/net/wireless/ath/ath12k/reg.c index 439d61f284d8..ea03f3f50e50 100644 --- a/drivers/net/wireless/ath/ath12k/reg.c +++ b/drivers/net/wireless/ath/ath12k/reg.c @@ -55,6 +55,24 @@ ath12k_reg_notifier(struct wiphy *wiphy, struct regulatory_request *request) ath12k_dbg(ar->ab, ATH12K_DBG_REG, "Regulatory Notification received for %s\n", wiphy_name(wiphy)); + if (request->initiator == NL80211_REGDOM_SET_BY_DRIVER) { + ath12k_dbg(ar->ab, ATH12K_DBG_REG, + "driver initiated regd update\n"); + if (ah->state != ATH12K_HW_STATE_ON) + return; + + for_each_ar(ah, ar, i) { + ret = ath12k_reg_update_chan_list(ar); + if (ret) { + ath12k_warn(ar->ab, + "failed to update chan list for pdev %u, ret %d\n", + i, ret); + break; + } + } + return; + } + /* Currently supporting only General User Hints. Cell base user * hints to be handled later. * Hints from other sources like Core, Beacons are not expected for @@ -211,7 +229,6 @@ int ath12k_regd_update(struct ath12k *ar, bool init) struct ieee80211_regdomain *regd, *regd_copy = NULL; int ret, regd_len, pdev_id; struct ath12k_base *ab; - int i; ab = ar->ab; @@ -275,11 +292,7 @@ int ath12k_regd_update(struct ath12k *ar, bool init) goto err; } - rtnl_lock(); - wiphy_lock(hw->wiphy); - ret = regulatory_set_wiphy_regd_sync(hw->wiphy, regd_copy); - wiphy_unlock(hw->wiphy); - rtnl_unlock(); + ret = regulatory_set_wiphy_regd(hw->wiphy, regd_copy); kfree(regd_copy); @@ -290,15 +303,6 @@ int ath12k_regd_update(struct ath12k *ar, bool init) goto skip; ah->regd_updated = true; - /* Apply the new regd to all the radios, this is expected to be received only once - * since we check for ah->regd_updated and allow here only once. - */ - for_each_ar(ah, ar, i) { - ab = ar->ab; - ret = ath12k_reg_update_chan_list(ar); - if (ret) - goto err; - } skip: return 0; err: @@ -770,6 +774,7 @@ void ath12k_regd_update_work(struct work_struct *work) void ath12k_reg_init(struct ieee80211_hw *hw) { hw->wiphy->regulatory_flags = REGULATORY_WIPHY_SELF_MANAGED; + hw->wiphy->flags |= WIPHY_FLAG_NOTIFY_REGDOM_BY_DRIVER; hw->wiphy->reg_notifier = ath12k_reg_notifier; }