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Mon, 09 Nov 2026 11:53:03 -0800 (PST) Received: from localhost ([2a03:2880:9ff:66::]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-37520bfb58dsm839952eec.18.2026.11.09.11.53.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 11:53:02 -0800 (PST) Date: Mon, 9 Nov 2026 11:50:48 -0800 From: Stanislav Fomichev To: Mina Almasry Cc: netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Borkmann , Nikolay Aleksandrov , David Wei , Bobby Eshleman , Dragos Tatulea Subject: Re: [PATCH net-next v2 3/6] net: guard memory provider RX queue open and close on unregister Message-ID: References: <20261108055809.2122934-1-almasrymina@google.com> <20261108055809.2122934-4-almasrymina@google.com> 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=utf-8 Content-Disposition: inline In-Reply-To: <20261108055809.2122934-4-almasrymina@google.com> On 11/08, Mina Almasry wrote: > When a memory provider RX queue is leased to a virtual netdev, > netif_mp_open_rxq() and netif_mp_close_rxq() redirect through > rxq->lease and lock the physical backing netdev directly rather than via > netdev_get_by_index_lock(). This raises two issues during netdev > unregistration: > > 1. In __netif_mp_open_rxq(), the physical backing netdev may already be > in NETREG_UNREGISTERING (after dev_shutdown() and > dev_memory_provider_uninstall() have run on it, before cascaded > unregistration of the virtual leasee tears down the lease). Reject > opening an RX queue if dev->reg_state != NETREG_REGISTERED. > 2. In __netif_mp_close_rxq(), when the physical backing netdev > unregisters before the virtual leasee, dev_memory_provider_uninstall() > on the physical netdev does not uninstall the virtual queues, so > phys_rxq->mp_params remains populated until the virtual leasee's > netif_rxq_cleanup_unlease() or socket teardown runs. At that point > the physical netdev has already gone through dev_shutdown() and must > not call netdev_rx_queue_reconfig(). When dev->reg_state > > NETREG_REGISTERED, clear rxq->mp_params and return 0. > > Signed-off-by: Mina Almasry > --- > net/core/netdev_rx_queue.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c > index a7261fedd5e76..85ae5abf16b8e 100644 > --- a/net/core/netdev_rx_queue.c > +++ b/net/core/netdev_rx_queue.c > @@ -193,6 +193,14 @@ static int __netif_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx, > struct netdev_rx_queue *rxq; > int ret; > > + /* A leased physical dev is locked via rxq->lease rather than > + * netdev_get_by_index_lock(), so check reg_state under its lock. > + */ > + if (dev->reg_state != NETREG_REGISTERED) { > + NL_SET_ERR_MSG(extack, "Device is being unregistered"); > + return -ENODEV; > + } nit: wonder if we should keep lease vs non-lease handling in the callers? netif_mp_open_rxq/netif_mp_close_rxq already handle this, and __ variants seem to be unaware of the leasing abstractions. Maybe put them into some new lease-valid helper? So we can keep these tricky details in a single place, similar to netdev_put_lock? netif_lease_valid() { return netif_is_alive && netif_device_present } ?