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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-31ebc75d8d6sm10610340eec.4.2026.08.13.10.25.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Aug 2026 10:25:12 -0700 (PDT) Message-ID: <0bac4c07-6c78-478c-b3ec-1d897cdd8acf@oss.qualcomm.com> Date: Thu, 13 Aug 2026 10:25:11 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 4/4] wifi: ath12k: implement custom wake_tx_queue with flow control To: Jose Ignacio Tornos Martinez Cc: ath11k@lists.infradead.org, ath12k@lists.infradead.org, jjohnson@kernel.org, linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, pengdonglin , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= References: <0b72231d-59f8-49bf-82a0-76d2c7862729@oss.qualcomm.com> <20260811111405.397112-1-jtornosm@redhat.com> Content-Language: en-US From: Jeff Johnson In-Reply-To: <20260811111405.397112-1-jtornosm@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=NsfhtcdJ c=1 sm=1 tr=0 ts=6a7dfdfa cx=c_pps a=0uOsjrqzRL749jD1oC5vDA==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=aIEVAj3FgTlWRZ7fGdMA:9 a=QEXdDO2ut3YA:10 a=mQ_c8vxmzFEMiUWkPHU9:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEzMDEyNSBTYWx0ZWRfX8CL+b38PzvBM FVcJDR6a60um4q7nIPkzH1HirwvxuNkMgtj/QW6Ny+F5zRlCLuJsF9i0XN/C6bG67kfElcByBxL /WOBtD+9Ssg/ZWnvrtR+cW6bCOsqNj2NLeodsjXf+cvjhZ45/UazlpRijj0pOE60/byxyINqmir 2U5ECajEwGBkSI4X0iA3q05BqpKtiU2Cdptng1ta4JMHYMCbWU3lRmRr4FIx6T29qaKRXgb5X9Z PSLqvRXFXbd4cgBhfQJsDxeXShsk001dF5RDpyBrN9Hzm/VWXsmCK4ytZG2Q2Ei0J5KqRbq2Gu9 jNMDkI1O+meKA+6U178ZYfEGslw2TjksArHjAiu1sp35yqWW+gf2c00Illmb2UCpAmVUlMxYpSi adzEG0HgBHMm1xSvS8IH12tudm7KdawMlu0Ehd0K7f13gx/jb1CwuKSOB/usmQCMMgFNLpEFrlp 66SA90sPLTUkQ840wgA== X-Proofpoint-ORIG-GUID: 9qvUYnnjt2b7CErhpAYGXmdx9ep1qsnm X-Proofpoint-GUID: 9qvUYnnjt2b7CErhpAYGXmdx9ep1qsnm X-Proofpoint-Spam-Info: AW1haW4tMjYwODEzMDEyNSBTYWx0ZWRfX5iQW1O58v7Gs 37Zv3TJur12SfjLaUlQK/GuCQkz5rZb37iTJji5o8m4Kj46Xcvn5ettlYOHPbI0kj+C4xntL4p8 5mOihzy7tKGOlFPYXE9lcJmqY7SrsWg= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-13_05,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 adultscore=0 clxscore=1015 priorityscore=1501 malwarescore=0 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608130125 On 8/11/2026 4:14 AM, Jose Ignacio Tornos Martinez wrote: > Keeping rcu_read_lock() for the entire function is intentional. > ath12k_wifi7_mac_op_tx() calls rcu_dereference() internally (on ahvif->link[] > and ahsta->link[]), and with CONFIG_DEBUG_LOCK_ALLOC, rcu_dereference() checks > lock_is_held(&rcu_lock_map) via rcu_read_lock_held(). > Only an explicit rcu_read_lock() sets rcu_lock_map and spin_lock_bh() does not, > so releasing early would trigger lockdep warnings. hmm, so some of the following commits are broken? https://lore.kernel.org/all/20250916044735.2316171-1-dolinux.peng@gmail.com/ In particular the one that I merged into ath9k: https://lore.kernel.org/all/20250916044735.2316171-15-dolinux.peng@gmail.com/ diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c index 0ac9212e42f7..4a0f465aa2fe 100644 --- a/drivers/net/wireless/ath/ath9k/xmit.c +++ b/drivers/net/wireless/ath/ath9k/xmit.c @@ -1993,7 +1993,6 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq) ieee80211_txq_schedule_start(hw, txq->mac80211_qnum); spin_lock_bh(&sc->chan_lock); - rcu_read_lock(); if (sc->cur_chan->stopped) goto out; @@ -2011,7 +2010,6 @@ void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq) } out: - rcu_read_unlock(); spin_unlock_bh(&sc->chan_lock); ieee80211_txq_schedule_end(hw, txq->mac80211_qnum); } I fed that into my review agent and it confirms your observation: The change works correctly on production kernels without CONFIG_DEBUG_LOCK_ALLOC. It will produce a false lockdep splat on debug kernels with CONFIG_PROVE_RCU because rcu_dereference() checks rcu_read_lock_held() which requires an explicit rcu_read_lock(), not just a spinlock. I have a fixup for ath9k which does: 171 - ratetbl = rcu_dereference(sta->rates); 171 + ratetbl = rcu_dereference_bh(sta->rates); Should ath12k also use rcu_dereference_bh()? /jeff