From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793720103; b=J4TmPOAZ4dvk5WuCRWssT3xWGoU/6ziUP/Wc+5HkaoniIKxtoP9aFuIzzMasEyKBNgxK gieMB9Ik8A7g011tiw7eCskkUsBC1pNS26jDpHkLGc2ZQIHJXXnFBrkEMMwzgO8FULXPf jgwOMDkPWpNk1Ubsv7mXNyk5NwfnwBlwDLzBiXVWZcsCwyPC3o5u9iZaU1OtiKBvmWXtx np3u4QBxzl5hRHMutgXWvKyYWswy2rUuBe6okYF/I3vr6WwZH6EkDv/GT9D8raFPcJrKf FdoVgVz2lhFG3b3Pw0mb621lBHunWMgrO0XyDktnVW79ACtlcn4nVs8eSq7p9PpxGHA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793720103; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=TY0hZsWLPRTQMxeVW6Na0ctagqhgwKOHthul7CCfGVg=; b=wIuA6NivOVAa0ivTQN/rorEkeoaKjJ3TqTAngkVLven7+s2gBPsOJs+dNpnZFvHRMH19 MGBoXA+yG0wkHIZ3/y8HJSaFdaLllTe1zGwKNH4HImc1qNQWHC4qIHaV3vojsrCbHSl8i diERpT375uuz6kIL25jKXvZ8dCLMqQA36xhIZrRMT4V2I8wdoggCC/IuCL6udGzKabC98 g+c7zxaN2P5kjvxStxUqI4tJMyfktRP7UVtTbQgBNkr4n1ojwcd2bh5kOFWEsn6VfUFl6 r59CYR/P53Llr8Ds0+7J1bgKHUNhS2d9gUBnpBfDM1bysNlO+QjrXdHJt72w23aaECQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jV9aTeQa; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8DB15606D813 for ; Tue, 3 Nov 2026 15:35:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=jV9aTeQa Received: by smtp.kernel.org (Postfix) with ESMTPSA id F19831F000C1; Tue, 3 Nov 2026 15:35:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793720103; bh=TY0hZsWLPRTQMxeVW6Na0ctagqhgwKOHthul7CCfGVg=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=jV9aTeQa3hlEbAZwz9/KVdhWMd3daljzrTB522wl/MzTlrtXvYYSSiVXm7dXb8Qe5 DJ4UcpYG6RqoDU8TxjVdlQ+fztueQnJcmCyDmpCfb+Pk0oNXq3pd83H64kkbg65gvD g7QFuHSr3SQqlkw/sTMmH5qFqtvMZaFEhLwKhIrxReqxGZW/Oqp/w6TdqGDWXrovS6 peHmZC12V5BcYH1aYEYO9zXzCQNP0a4awdkhRQK16/pR9qT5kD9BBQVeSuYyLYrFoh 0fvEX55wK4mqlCNzL8WtvUX/Bxq4AO92HV1U2X74dmyU5v6eirZI/ciLA/LK/XYkgf csMmLf6dkQr6g== Date: Tue, 3 Nov 2026 08:35:01 -0700 From: Keith Busch To: Yingjie Wang <1075151112@qq.com> Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me, kch@nvidia.com, axboe@kernel.dk, linux-kernel@vger.kernel.org Subject: Re: [PATCH] nvmet: reject keep-alive timeouts that would overflow Message-ID: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Oct 30, 2026 at 04:46:22PM +0800, Yingjie Wang wrote: > nvmet_set_feat_kato() and nvmet_alloc_ctrl() convert the 32-bit > millisecond KATO from the host to seconds with DIV_ROUND_UP(kato, 1000). > The addition in DIV_ROUND_UP() is done in 32 bits, so any KATO above > 4294966296 ms wraps around and rounds to 0 seconds. A Set Features > command with KATO 0xffffffff then succeeds but disables the keep-alive > timer: Get Features returns 0 and Keep Alive fails with Keep Alive > Timeout Invalid. A Connect command with such a KATO creates a controller > without a keep-alive timer. > > The converted value has more consumers that can overflow. Get Features > multiplies it by 1000, and the timer paths multiply it by HZ in 32 bits > and arm a delay that must not exceed MAX_JIFFY_OFFSET. > > Reject a KATO whose rounded value does not fit all of these. Return Keep > Alive Timeout Invalid from both Set Features and Connect. Validate Set > Features before stopping the current timer so a failed update leaves its > timeout unchanged. Round in 64 bits. A KATO of 0 keeps its current > meaning. Thanks, applied to nvme-7.4.