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 592742EBDC3; Tue, 15 Jul 2025 13:54:04 +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=1752587645; cv=none; b=LgJevWxCsLS4Kt03vntLrsA+GRh4esI6YX1NPxtBhPn/k/LJn5meUI0zSyhaL0NnbNlhVjExoqAtwWHPadiE2zrlU8QhLREl249xtnmu4JqnW9IETgueRhQ1tDZOsv4JAGL3mQoXWlLFSKK4dHmI2YUwCUTOI00i++gdda1qzgE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752587645; c=relaxed/simple; bh=1xRksTaDRgRjBjZIJNwdzAtfvCb5wQYItHCj8+duVLM=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=fAyuU3oArqg1xlqj/AJwzl8VnFyzKSfwitrIFZDNNugn5LHjFsOLRQgJlLVDdFdoNUtv+bisnnXRLry2rw2ZVmSNAP3JMgI1uJHho2xNS/3uNj/Ae356Ot/skSAJXY0hYK92VH/zJXDSfLekVbCN01j8rMexqq08kCq/TUq5d9U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sXFQbtwh; 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="sXFQbtwh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 658B4C4CEE3; Tue, 15 Jul 2025 13:54:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752587644; bh=1xRksTaDRgRjBjZIJNwdzAtfvCb5wQYItHCj8+duVLM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sXFQbtwhjlensPrNb2Ua3WXJt8ii6PGJWzKy6I5QxY2HwOYYAwr6TleWr5QCTHtVY 2O1svq0fKeTw/YpRluEQ1C+Mbk1p/5PN/nDIJpxlEvPvA5N7/mM40Vj6wO+4tUAc4B UD1L/LDaw81sCJgmz9O/im8Jl2RPJE3idnsiF8U7NBfE9kqhAjro9UIdfqQIf4jAaW uneMK9bvk5j/Fvbyda7xa/Gov4uSi+Zxh1vd0cwNIcQb94i4zDB6UUjBN9qtC90OX0 YXzoy5PbJvyaY7xE+fTLcNvtIKtwX6ql58xx2LTxjOlbv8tSsbiOLE5L/DCRrH71Cw iBGkKCeLarqYg== Date: Tue, 15 Jul 2025 06:54:03 -0700 From: Jakub Kicinski To: John Ernberg Cc: Oliver Neukum , Andrew Lunn , "David S . Miller" , Eric Dumazet , Paolo Abeni , Ming Lei , "netdev@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH] net: usbnet: Avoid potential RCU stall on LINK_CHANGE event Message-ID: <20250715065403.641e4bd7@kernel.org> In-Reply-To: <74a87648-bc02-4edb-9e6a-102cb6621547@actia.se> References: <20250710085028.1070922-1-john.ernberg@actia.se> <20250714163505.44876e62@kernel.org> <74a87648-bc02-4edb-9e6a-102cb6621547@actia.se> Precedence: bulk X-Mailing-List: linux-kernel@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 Tue, 15 Jul 2025 07:15:51 +0000 John Ernberg wrote: > > I'm worried that this is still racy. > > Since usbnet_bh checks if carrier is ok and __handle_link_change() > > checks the opposite something must be out of sync if both run. > > Most likely something restored the carrier while we're still handling > > the previous carrier loss. > > There could definitely be other factors, I'll try to dig some in > cdc_ether and see if something there could be causing problems for the > usbnet core. > I honestly kinda stopped digging when I found unlink_urbs() being > wrapped with a pause/unpause at another place tied to a commit seeing a > similar issue. Looking at cdc_ether: static void usbnet_cdc_zte_status(struct usbnet *dev, struct urb *urb) [...] if (event->wValue && netif_carrier_ok(dev->net)) netif_carrier_off(dev->net); This looks sus. Is the Gemalto Cinterion PLS83-W ZTE based?