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([2620:10d:c092:600::1:72cc]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-611f7365c7bsm8194693a12.62.2025.07.17.02.15.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Jul 2025 02:15:53 -0700 (PDT) Message-ID: <6e4a4ae7-b84e-470d-81e9-a58ecf9c9157@gmail.com> Date: Thu, 17 Jul 2025 10:17:17 +0100 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v10 02/12] netmem: use netmem_desc instead of page to access ->pp in __netmem_get_pp() To: Mina Almasry , Byungchul Park , "Lobakin, Aleksander" Cc: willy@infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, akpm@linux-foundation.org, andrew+netdev@lunn.ch, toke@redhat.com, david@redhat.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com, wei.fang@nxp.com, shenwei.wang@nxp.com, xiaoning.wang@nxp.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com, hkelam@marvell.com, bbhushan2@marvell.com, tariqt@nvidia.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, mbloch@nvidia.com, danishanwar@ti.com, rogerq@kernel.org, nbd@nbd.name, lorenzo@kernel.org, ryder.lee@mediatek.com, shayne.chen@mediatek.com, sean.wang@mediatek.com, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, horms@kernel.org, m-malladi@ti.com, krzysztof.kozlowski@linaro.org, matthias.schiffer@ew.tq-group.com, robh@kernel.org, imx@lists.linux.dev, intel-wired-lan@lists.osuosl.org, linux-arm-kernel@lists.infradead.org, linux-wireless@vger.kernel.org, linux-mediatek@lists.infradead.org References: <20250714120047.35901-1-byungchul@sk.com> <20250714120047.35901-3-byungchul@sk.com> <20250715013626.GA49874@system.software.com> <20250716045124.GB12760@system.software.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/16/25 20:41, Mina Almasry wrote: ...>> I will kill __netmem_get_pp() as you and I prefer. However, >> __netmem_get_pp() users e.i. libeth_xdp_return_va() and >> libeth_xdp_tx_fill_buf() should be altered. I will modify the code like: >> >> as is: __netmem_get_pp(netmem) >> to be: __netmem_nmdesc(netmem)->pp >> >> Is it okay with you? >> > > When Pavel and I were saying 'remove __netmem_get_pp', I think we > meant to remove the entire concept of unsafe netmem -> page > conversions. I think we both don't like them. From this perspective, > __netmem_nmdesc(netmem)->pp is just as bad as __netmem_get_pp(netmem). Yes. It'd great to have all of them gone. IMHO it's much better to let the caller do the casting so at least it's explicit and assumptions are not hidden. E.g. instead of pp = __netmem_nmdesc(netmem)->pp; It'd be struct page *page = __netmem_to_page(netmem); page_to_nmdesc(page)->pp; // or page_get_pp(page), or whatever the helper is That might be easier as well. -- Pavel Begunkov