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([2620:10d:c091:500::1:d15c]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-89ecc091f14sm118065586d6.16.2026.04.01.06.02.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 01 Apr 2026 06:02:36 -0700 (PDT) Message-ID: <1ec0c6e5-4c5a-436f-8d43-6f6e31e66b02@gmail.com> Date: Wed, 1 Apr 2026 09:02:35 -0400 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 net-next 3/5] psp: add a new netdev event for dev unregister To: Wei Wang Cc: netdev@vger.kernel.org, Jakub Kicinski , Willem de Bruijn , David Wei , Andrew Lunn , "David S . Miller" , Eric Dumazet , Simon Horman , Wei Wang References: <20260330223143.2394706-1-weibunny.kernel@gmail.com> <20260330223143.2394706-4-weibunny.kernel@gmail.com> <1d013236-e945-46fc-8acb-c7ab9ac32a1f@gmail.com> Content-Language: en-US From: Daniel Zahka In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 3/31/26 5:51 PM, Wei Wang wrote: > On Tue, Mar 31, 2026 at 6:30 AM Daniel Zahka wrote: >> >> On 3/30/26 6:31 PM, Wei Wang wrote: >>> +static bool psp_notifier_registered; >>> + >>> +/** >>> + * psp_attach_netdev_notifier() - register netdev notifier on first use >>> + * >>> + * Register the netdevice notifier when the first device association >>> + * is created. In many installations no associations will be created and >>> + * the notifier won't be needed. >>> + * >>> + * Must be called without psd->lock held, due to lock ordering: >>> + * rtnl_lock -> psd->lock (the notifier callback runs under rtnl_lock >>> + * and takes psd->lock). >>> + */ >>> +void psp_attach_netdev_notifier(void) >>> +{ >>> + if (READ_ONCE(psp_notifier_registered)) >>> + return; >>> + >>> + mutex_lock(&psp_devs_lock); >>> + if (!psp_notifier_registered) { >>> + if (!register_netdevice_notifier(&psp_netdev_notifier)) >>> + WRITE_ONCE(psp_notifier_registered, true); >>> + } >>> + mutex_unlock(&psp_devs_lock); >>> +} >> ... >>> +int psp_device_get_locked_dev_assoc(const struct genl_split_ops *ops, >>> + struct sk_buff *skb, struct genl_info *info) >>> +{ >>> + psp_attach_netdev_notifier(); >>> + >>> + return __psp_device_get_locked(ops, skb, info, false); >>> +} >> >> From an AI review, but seems plausible to me: >> >> psp_device_get_locked_dev_assoc() will proceed even in the path where >> register_netdevice_notifier() and psp_notifier_registered stays false. >> > This behavior is intended. In case register_netdevice_notifier() fails > for some reason, this current dev_assoc will proceed but the next > dev_assoc operation will try to register_netdevice_notifier() again. That doesn't sound correct to me. If the notifier is not registered, but the dev-assoc command succeeds, then an entry can leak in the psd->assoc_dev_list during a NETDEV_UNREGISTER.