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Wed, 06 May 2026 03:39:22 -0700 (PDT) Received: from houminxi ([72.244.37.221]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-43454cbbbd7sm15307827fac.10.2026.05.06.03.39.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 03:39:22 -0700 (PDT) From: Minxi Hou To: cole@unwrap.rs Cc: linux-wireless@vger.kernel.org, greearb@candelatech.com, miriam.rachel.korenblit@intel.com, johannes@sipsolutions.net, Minxi Hou Subject: Re: [PATCH v3 3/3] wifi: iwlwifi: mld: skip TX when firmware is dead Date: Wed, 6 May 2026 18:39:07 +0800 Message-ID: <20260506103907.1783441-1-houminxi@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420174406.128254-4-cole@unwrap.rs> References: <20260420174406.128254-4-cole@unwrap.rs> Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, 20 Apr 2026 10:44:06 -0700, Cole Leavitt wrote: > When firmware encounters an error, STATUS_FW_ERROR is set but the > mac80211 TX path continues pulling frames from TXQs. Each frame > fails at iwl_trans_tx() which checks STATUS_FW_ERROR and returns > -EIO, but iwl_mld_tx_from_txq() keeps looping over every queued > frame. This burns CPU in a tight loop on dead firmware and can > cause soft lockups during firmware error recovery. I can confirm this on BE200 with a tproxy VPN daemon that keeps many concurrent TCP flows open. A firmware NMI causes 22-30 second system-wide soft lockups affecting 11-34 CPUs. Setup: Intel BE200 Wi-Fi 7 [8086:272b] rev 1a Firmware 101.6e695a70.0 (gl-c0-fm-c0-c101.ucode) Kernel 6.19.12-200.fc43.x86_64 (Fedora 43) Driver: iwlmld Workload: tproxy daemon (Go, ~50 goroutines doing TCP write()) Reproducer: echo 1 > /sys/kernel/debug/ieee80211/phy0/iwlwifi/iwlmld/fw_nmi The call trace consistently shows goroutines spinning in: write() -> tcp_sendmsg -> __dev_queue_xmit -> ... -> iwl_mld_tx_from_txq -> iwl_mld_tx_skb carrier stays 1 throughout the entire crash, so mac80211 never stops queuing frames. The lockup resolves only after iwlwifi completes the firmware SW reset (~22-30s). Firmware occasionally crashes again within 15 seconds of restart, causing cascading lockups. This matches exactly what your patch addresses. Regards, Minxi Hou