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Miller" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-VR-OUT-STATUS: OK X-VR-OUT-SCORE: -100 X-VR-OUT-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedufedrvdefkedgvdeiucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuggftfghnshhusghstghrihgsvgdpffftgfetoffjqffuvfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepggfhfffkuffvtgesthdtredttddtjeenucfhrhhomhepufhtvghphhgvnhcuqfgsvghrhhholhhtiigvrhcuoehsthgvvhhivgesqhhrphhffhdrnhgvtheqnecukfhppedvtdelrdekhedrvddtkedrudejfeenucfrrghrrghmpehmohguvgepshhmthhppdhhvghlohepmhgrihhlqdhljhduqdhfudejfedrghhoohhglhgvrdgtohhmpdhinhgvthepvddtledrkeehrddvtdekrddujeefpdhrvghtuhhrnhdqphgrthhhpefuthgvphhhvghnucfqsggvrhhhohhlthiivghruceoshhtvghvihgvsehqrhhpfhhfrdhnvghtqedpmhgrihhlfhhrohhmpehsthgvvhhivgesqhhrphhffhdrnhgvthdpnhhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgnecuvehluhhsthgvrhfuihiivgeptd Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Wireless networking goes down on Acer C720P Chromebook (bisected) Culprit: 7a89233a ("mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue") I found that the newest kernel (5.4) displayed a curious issue on my Acer C720P Chromebook: shortly after bringing networking up, all connections would suddenly fail. I discovered that I could consistently reproduce the issue by ssh'ing into the machine and running 'dmesg' -- on a non-working kernel; I would get partial output, and then the connection would completely hang. This was so consistent, in fact, that I was able to leverage it to automate the process from 'git bisect run'. KEYWORDS: c720p, chromebook, wireless, networking, mac80211 KERNEL: any kernel containing commit 7a89233a ("mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue") I find this bit in the offending commit's message suspicious: > This patch does *not* include any mechanism to wake a throttled TXQ again, > on the assumption that this will happen anyway as a side effect of whatever > freed the skb (most commonly a TX completion). Methinks this assumption is not a fully valid one. I'll be happy to test any patches. If you need some printk calls, just tell me where to put 'em. This is the card: 01:00.0 Network controller: Qualcomm Atheros AR9462 Wireless Network Adapter (rev 01) Subsystem: Foxconn International, Inc. AR9462 Wireless Network Adapter Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- SERR-