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[73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id 98e67ed59e1d1-329e4f084f8sm2185632a91.10.2025.09.02.08.54.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Sep 2025 08:54:41 -0700 (PDT) Date: Tue, 2 Sep 2025 08:54:40 -0700 From: Stanislav Fomichev To: Jakub Kicinski Cc: Mina Almasry , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Stanislav Fomichev Subject: Re: [PATCH net-next v1] net: devmem: NULL check netdev_nl_get_dma_dev return value Message-ID: References: <20250829220003.3310242-1-almasrymina@google.com> <20250829175222.32d500ca@kernel.org> 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-Disposition: inline In-Reply-To: <20250829175222.32d500ca@kernel.org> On 08/29, Jakub Kicinski wrote: > On Fri, 29 Aug 2025 21:59:38 +0000 Mina Almasry wrote: > > netdev_nl_get_dma_dev can return NULL. This happens in the unlikely > > scenario that netdev->dev.parent is NULL, or all the calls to the > > ndo_queue_get_dma_dev return NULL from the driver. > > I probably have Friday brain but I don't see what you mean.. > In net-next net_devmem_bind_dmabuf() gets a dma_dev and returns > -EOPNOTSUPP PTR if its NULL. +1, the description and the fix are confusing. Unless I'm missing something, the intent seems to be to avoid hitting a WARN_ON in dma_buf_attach (really dma_buf_dynamic_attach) when the dma_dev is NULL. Mina, can we do this in the callers of netdev_queue_get_dma_dev?