From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C7EC15479B; Fri, 18 Jul 2025 23:37:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752881844; cv=none; b=eBHWs8hoX8q1HggxEYx4Sv5WfcYggo8/wHaLijsH9fFS4w+97IpGv/2fEvqHhn9G66pa89OTJJeOv1HkA3ZwTRusEkSOzUFmRPhZ1ze+VdPKn4IwH9LgLKgOV2KWvGd7l2UN2GFb1u0CXHZPKXfRJUTbmJCv03P547g8T6OQaKE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752881844; c=relaxed/simple; bh=i/DZrEEXHs8Q2rMc5+5X5kEhFG1UD6Uqa/oIKPuu3sk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=fgFXngTAIZ5KtcgCPJcEwGw9QBnOA15LLfYjn8xALblvidc4L2k0OkLji/l/RrN8hG+yk6kejijRcEbX0RQtdcykE2fXcBRyPN/5vQxXnySC5KjsfwV4iyaV5BRyYJsMmwWtdf4qSjtMjmxCSBjoEoMCW+uA9jXHsI3S0Aun8fE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mj4qVPGm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mj4qVPGm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE177C4CEEB; Fri, 18 Jul 2025 23:37:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752881844; bh=i/DZrEEXHs8Q2rMc5+5X5kEhFG1UD6Uqa/oIKPuu3sk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Mj4qVPGmWmNQQrdnHAUdYzajX0sjKDMW40Eo97OX5sQwSOfHNgE7rPJq3SE9GQ009 S751fReuKalJHFKOUAZMXH/OlvLbmCLwlLJoEF3/AXjQsggREFe5gdHKd8241bGvON oQ7YeDMkM/lAShwlB5f0CyPF+S+G7N08LDprISYGvztBj1b0pBUYGOD1g3ONVtq8P1 p6RA6my4+NXMXO8fXICdG2tay9nH83+9WDBIkNIqIhrf4WpknNKuw4OKWc/Yugikar /4cAMRWST2ccjcMfoth4CJ3JIubteRouFFEGcFV6W5gYCcpaZVbyTtjK8ZI3/OXSoc o7quIgv6QzsdA== Date: Fri, 18 Jul 2025 16:37:23 -0700 From: Jakub Kicinski To: Haiyang Zhang , kuniyu@google.com Cc: linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, haiyangz@microsoft.com, kys@microsoft.com, wei.liu@kernel.org, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, davem@davemloft.net, sdf@fomichev.me, ahmed.zaki@intel.com, aleksander.lobakin@intel.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net: core: Fix the loop in default_device_exit_net() Message-ID: <20250718163723.4390bd7d@kernel.org> In-Reply-To: <1752870014-28909-1-git-send-email-haiyangz@linux.microsoft.com> References: <1752870014-28909-1-git-send-email-haiyangz@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-hyperv@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 18 Jul 2025 13:20:14 -0700 Haiyang Zhang wrote: > The loop in default_device_exit_net() won't be able to properly detect the > head then stop, and will hit NULL pointer, when a driver, like hv_netvsc, > automatically moves the slave device together with the master device. > > To fix this, add a helper function to return the first migratable netdev > correctly, no matter one or two devices were removed from this net's list > in the last iteration. FTR I think that what the driver is trying to do is way too hacky, and it should be fixed instead. But I defer to Kuniyuki for the final word, maybe this change is useful for other reasons..