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From: Kent Overstreet To: Thomas Gleixner Subject: Re: [PATCH v2 06/12] mm/execmem: introduce execmem_data_alloc() Message-ID: <20230618231431.4aj3k5ujye22sqai@moria.home.lan> References: <20230616085038.4121892-1-rppt@kernel.org> <20230616085038.4121892-7-rppt@kernel.org> <87jzw0qu3s.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87jzw0qu3s.ffs@tglx> X-Migadu-Flow: FLOW_OUT X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , x86@kernel.org, Catalin Marinas , linux-mips@vger.kernel.org, Song Liu , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Nadav Amit , linux-s390@vger.kernel.org, Helge Deller , Huacai Chen , Russell King , "Naveen N. Rao" , linux-trace-kernel@vger.kernel.org, Will Deacon , Heiko Carstens , Steven Rostedt , loongarch@lists.linux.dev, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Thomas Bogendoerfer , linux-parisc@vger.kernel.org, Puranjay Mohan , linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dinh Nguyen , Luis Chamberlain , Palmer Dabbelt , linux-modules@vger.kernel.org, Andrew Morton , Rick Edgecombe , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , Mike Rapoport Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Jun 19, 2023 at 12:32:55AM +0200, Thomas Gleixner wrote: > Mike! > > Sorry for being late on this ... > > On Fri, Jun 16 2023 at 11:50, Mike Rapoport wrote: > > > > +void *execmem_data_alloc(size_t size) > > +{ > > + unsigned long start = execmem_params.modules.data.start; > > + unsigned long end = execmem_params.modules.data.end; > > + pgprot_t pgprot = execmem_params.modules.data.pgprot; > > + unsigned int align = execmem_params.modules.data.alignment; > > + unsigned long fallback_start = execmem_params.modules.data.fallback_start; > > + unsigned long fallback_end = execmem_params.modules.data.fallback_end; > > + bool kasan = execmem_params.modules.flags & EXECMEM_KASAN_SHADOW; > > While I know for sure that you read up on the discussion I had with Song > about data structures, it seems you completely failed to understand it. > > > + return execmem_alloc(size, start, end, align, pgprot, > > + fallback_start, fallback_end, kasan); > > Having _seven_ intermediate variables to fill _eight_ arguments of a > function instead of handing in @size and a proper struct pointer is > tasteless and disgusting at best. > > Six out of those seven parameters are from: > > execmem_params.module.data > > while the KASAN shadow part is retrieved from > > execmem_params.module.flags > > So what prevents you from having a uniform data structure, which is > extensible and decribes _all_ types of allocations? > > Absolutely nothing. The flags part can either be in the type dependend > part or you make the type configs an array as I had suggested originally > and then execmem_alloc() becomes: > > void *execmem_alloc(type, size) > > and > > static inline void *execmem_data_alloc(size_t size) > { > return execmem_alloc(EXECMEM_TYPE_DATA, size); > } > > which gets the type independent parts from @execmem_param. > > Just read through your own series and watch the evolution of > execmem_alloc(): > > static void *execmem_alloc(size_t size) > > static void *execmem_alloc(size_t size, unsigned long start, > unsigned long end, unsigned int align, > pgprot_t pgprot) > > static void *execmem_alloc(size_t len, unsigned long start, > unsigned long end, unsigned int align, > pgprot_t pgprot, > unsigned long fallback_start, > unsigned long fallback_end, > bool kasan) > > In a month from now this function will have _ten_ parameters and tons of > horrible wrappers which convert an already existing data structure into > individual function arguments. > > Seriously? > > If you want this function to be [ab]used outside of the exec_param > configuration space for whatever non-sensical reasons then this still > can be either: > > void *execmem_alloc(params, type, size) > > static inline void *execmem_data_alloc(size_t size) > { > return execmem_alloc(&exec_param, EXECMEM_TYPE_DATA, size); > } > > or > > void *execmem_alloc(type_params, size); > > static inline void *execmem_data_alloc(size_t size) > { > return execmem_alloc(&exec_param.data, size); > } > > which both allows you to provide alternative params, right? > > Coming back to my conversation with Song: > > "Bad programmers worry about the code. Good programmers worry about > data structures and their relationships." Thomas, you're confusing an internal interface with external, I made the same mistake reviewing Song's patchset...