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([2620:10d:c092:600::1:b2ad]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae6e8294bf2sm467992366b.122.2025.07.12.04.58.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 12 Jul 2025 04:58:16 -0700 (PDT) Message-ID: <4a8b0a45-b829-462c-a655-af0bda10a246@gmail.com> Date: Sat, 12 Jul 2025 12:59:34 +0100 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 net-next v9 2/8] netmem: introduce utility APIs to use struct netmem_desc To: Byungchul Park , willy@infradead.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, kuba@kernel.org, almasrymina@google.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, hawk@kernel.org, akpm@linux-foundation.org, davem@davemloft.net, john.fastabend@gmail.com, andrew+netdev@lunn.ch, toke@redhat.com, tariqt@nvidia.com, edumazet@google.com, pabeni@redhat.com, saeedm@nvidia.com, leon@kernel.org, ast@kernel.org, daniel@iogearbox.net, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com References: <20250710082807.27402-1-byungchul@sk.com> <20250710082807.27402-3-byungchul@sk.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20250710082807.27402-3-byungchul@sk.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/10/25 09:28, Byungchul Park wrote: ...> + > static inline struct net_iov *netmem_to_net_iov(netmem_ref netmem) > { > if (netmem_is_net_iov(netmem)) > @@ -314,6 +340,21 @@ static inline netmem_ref netmem_compound_head(netmem_ref netmem) > return page_to_netmem(compound_head(netmem_to_page(netmem))); > } > > +#define nmdesc_to_page(nmdesc) (_Generic((nmdesc), \ > + const struct netmem_desc * : (const struct page *)(nmdesc), \ > + struct netmem_desc * : (struct page *)(nmdesc))) Considering that nmdesc is going to be separated from pages and accessed through indirection, and back reference to the page is not needed (at least for net/), this helper shouldn't even exist. And in fact, you don't really use it ... > +static inline struct netmem_desc *page_to_nmdesc(struct page *page) > +{ > + VM_BUG_ON_PAGE(PageTail(page), page); > + return (struct netmem_desc *)page; > +} > + > +static inline void *nmdesc_address(struct netmem_desc *nmdesc) > +{ > + return page_address(nmdesc_to_page(nmdesc)); > +} ... That's the only caller, and nmdesc_address() is not used, so just nuke both of them. This helper doesn't even make sense. Please avoid introducing functions that you don't use as a general rule. > + > /** > * __netmem_address - unsafely get pointer to the memory backing @netmem > * @netmem: netmem reference to get the pointer for -- Pavel Begunkov