From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f178.google.com (mail-pl1-f178.google.com [209.85.214.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9DDE21F9F47; Mon, 18 Aug 2025 16:56:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755536167; cv=none; b=rScWxgKaN2ZmJ4ESyjd5SvPMYLKxL5fs1QZAGctdqUaL0tqjVpm7pKEZcsATOz7c5lnUqOKJalHOKZzbgjZo9SEj7RJI1xs6XXD2KKDFPcn6ltRSVa63vTHi8hPyc1NarRD/5QN+yyKmKBrC4z2hkj5t3/oxNR4UbYncYXO/Gg4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755536167; c=relaxed/simple; bh=IFg0D4g6Egie7/QmgFZH3hnlqMPxOHmfSJD63T/Ug0M=; h=Message-ID:Date:MIME-Version:To:Cc:From:Subject:Content-Type; b=MKu57J326Q8TaRBSJ/L6RvnAQPYCYDXuXClI03jfRtxUOPnD50FyEe4JwJCQprJ+H1bEcSBtLelDxeEQNcoZORk8p7agb331LQaBC9dt8FqZ6B5SgjWWie4zXD3fVEB2ztDDKqEsfajw676rDJtcEvkDtbFK/7d4LSbFs2WOByU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kzalloc.com; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.214.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kzalloc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pl1-f178.google.com with SMTP id d9443c01a7336-244580692f3so4647275ad.1; Mon, 18 Aug 2025 09:56:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755536166; x=1756140966; h=content-transfer-encoding:organization:subject:from:cc:to :content-language:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=zcw7UQVd8NcuUoJtmjMZ4xGFWAzLft8voRj5P/6UCyA=; b=MhjN6XgAtyyJ3f9BlFko52UEvvZDC/2C9msJl68sKheiyBtZ9aX+mgam5yWv+7iWjx HL7zVoIBi/15SgCW/MBD0xgChPFr7aUmZjgZ+/UVCVI0G3kZqsGJfSPKaF3FeT3ZFrvP Ki4tOTWlIern2+3cY/agu5YdyXJVYij+7CZr2re00yvykQkEfU6gQLIUd6tQHuHrNNDd YhW6EFPkEcWkx7ChwyHtuMCT/6eCg8JZUJKuBdjvXvaC1r7FqOkMtDMRjdAApEiLj7H8 aTdHSZUhtrzbLBlXHjdol422KCC0wX3mR404xIgLWxk/8Q02FVQmBlw9MS6ocfpkClYO WevA== X-Forwarded-Encrypted: i=1; AJvYcCUBxBP2S23IlxLDqnmEJj72NFNLYtJrB8G+mdZ76wrbDsjfH9k9eWG5hUgbRWF75qDPNzBCyMZ/Fjz+m0cfh1A=@vger.kernel.org, AJvYcCW+UNZM+aYiYYP+c//0RC4v7yLRrXGPnflUQhYO5oQsMiBhQfNUSR6a0uHftnZur5KdKzZVsnBwAe0r7DM=@vger.kernel.org X-Gm-Message-State: AOJu0YyWkYCpPGoS1jgVYyBtp7nXTDWjncsgorTwx2RnccMwPbYk5pz5 5BwEcOcNtjvIZffTq4QYnyoPo6Hg2/7Kxo0JQOLKQHysYUmRhF7TjZsN X-Gm-Gg: ASbGncuvz7/2fwb98FkZSSrhyCx9Tg+NjPBGHWV5VbO00xwkkI1qCzHgCPbAiwz0nv3 tBf0+7JsigiDSV4VmIQ5TaIXfExZ2CWnzxgDrCv8OnWd0m1zEKpEUJfhzvxlssD8Iwu0HlbPqMV 31ATbvAVTXNktSIr5Ktmo7gILyMu8CL3dlr7ROspmwOnMGGtNHDwBs6hCf/uBvZB8Hss8QjNVjz PB0AaotQ0EBCZBefUfSGna7rP/XG7l43xEKR8VxKT3PLWQazgoKMa5l/X/UNJjkWpk8uM/DLftC rK9zIJhaHWpGpph7YoClA+m67emPXfVXU9AImlCiGtndanCf/gJouvZggK5mN77mdaSrnN9NlXS FEfuQsNtnZCsDozse+LV8fzl/bt2y+db/ X-Google-Smtp-Source: AGHT+IGnVrA59DmOzJy5E4sN18kKqIy9b2FRTAzN1UkHFYriAbF897/ODgMzzWDNmt9+Bqs94Fa7gg== X-Received: by 2002:a17:902:d4c1:b0:234:df51:d190 with SMTP id d9443c01a7336-2446d756119mr88110485ad.4.1755536165478; Mon, 18 Aug 2025 09:56:05 -0700 (PDT) Received: from [192.168.50.136] ([118.32.98.101]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2446cb09ff8sm85254045ad.50.2025.08.18.09.56.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Aug 2025 09:56:05 -0700 (PDT) Message-ID: Date: Tue, 19 Aug 2025 01:56:00 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: Johannes Berg Cc: Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , Jiri Kosina , Aaron Hill , Lukas Redlinger , Oleksii Shevchuk , =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , linux-wireless@vger.kernel.org, linux-rt-devel@lists.linux.dev, LKML From: Yunseong Kim Subject: [RFC] mac80211: Potential sleep in atomic context in __ieee80211_wake_txqs Organization: kzalloc Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, I found a potential PREEMPT_RT issue I noticed in __ieee80211_wake_txqs() static void __ieee80211_wake_txqs(struct ieee80211_sub_if_data *sdata, int ac) { ... local_bh_disable(); spin_lock(&fq->lock); ... } This sequence of local_bh_disable() followed by spin_lock(). On an RT-enabled system, spin_lock() is converted to a sleeping lock. Calling it immediately after local_bh_disable() creates a situation where a sleeping function is called from an atomic context, which will lead to a sleep in atomic context if the lock is contended. The conventional fix for this pattern is to replace the two lines with a single, RT-safe call to spin_lock_bh(&fq->lock). I wanted to bring this up for discussion before preparing a patch. Is this a valid concern, and would a patch to correct this locking be the right approach? Thank you for your time and consideration. Best regards, Yunseong Kim