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[34.86.60.15]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6dd18208102sm184228416d6.128.2025.01.07.12.31.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Jan 2025 12:31:50 -0800 (PST) Date: Tue, 07 Jan 2025 15:31:50 -0500 From: Willem de Bruijn To: Jakub Kicinski , Willem de Bruijn Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, stable@vger.kernel.org, jdamato@fastly.com, almasrymina@google.com, amritha.nambiar@intel.com, sridhar.samudrala@intel.com Message-ID: <677d8f3618080_2821742942a@willemb.c.googlers.com.notmuch> In-Reply-To: <20250107083609.55ddf0d6@kernel.org> References: <20250106180137.1861472-1-kuba@kernel.org> <677d27cc5d9b_25382b294fd@willemb.c.googlers.com.notmuch> <20250107083609.55ddf0d6@kernel.org> Subject: Re: [PATCH net] netdev: prevent accessing NAPI instances from another namespace Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Jakub Kicinski wrote: > On Tue, 07 Jan 2025 08:10:36 -0500 Willem de Bruijn wrote: > > > +/* must be called under rcu_read_lock(), as we dont take a reference */ > > > > Instead of function comments, invariant checks in code? > > > > Like in dev_get_by_napi_id: > > > > WARN_ON_ONCE(!rcu_read_lock_held()); > > Can I do it as a follow up? Adding the warning to napi_by_id() > reveals that napi_hash_add() currently walks the list without > holding the RCU lock :) Ah I should have noticed that :) Of course, or ignore in this case then.