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Thu, 05 Feb 2026 03:40:17 -0800 (PST) Received: from [192.168.88.32] ([216.128.11.114]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4830fe62fe7sm64825025e9.4.2026.02.05.03.40.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Feb 2026 03:40:17 -0800 (PST) Message-ID: Date: Thu, 5 Feb 2026 12:40:15 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v2] ppp: remove ppp->closing check To: Qingfang Deng , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , linux-ppp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260202092116.266568-1-dqfext@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20260202092116.266568-1-dqfext@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/2/26 10:21 AM, Qingfang Deng wrote: > The ppp->closing flag is used to test if an interface is closing down. > However, when .ndo_uninit() is called (where ppp->closing is set to 1), > dev_close() has already brought down the interface, and > synchronize_net() guarantees that no pending TX/RX in the network path > can take place. Thus, the check in the network path is unnecessary. > > For file operations - ppp_read(), ppp_write(), and ppp_poll(), can > normally still send or receive skbs. ppp_read() and ppp_poll() are safe > because ppp_dev_uninit() sets pf->dead before waking them up, causing > both to exit cleanly. Please report the accurate call sequence that would lead to such syscall complete cleanly. Also what if ndo_uninit() happens just after the user-space has been woken-up? > ppp_write() does not check pf->dead, but > ppp_push() verifies that ppp->channels list is not empty before sending. > > Remove the ppp->closing check. This still feel risky to me and it's not clear which would be the goal/gain. It this change performance oriented? If so please included actual figures. Thanks, Paolo