----- On Jun 17, 2021, at 8:12 PM, Andy Lutomirski luto@xxxxxxxxxx wrote: > On 6/17/21 7:47 AM, Mathieu Desnoyers wrote: > >> Please change back this #ifndef / #else / #endif within function for >> >> if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) { >> ... >> } else { >> ... >> } >> >> I don't think mixing up preprocessor and code logic makes it more readable. > > I agree, but I don't know how to make the result work well. > membarrier_sync_core_before_usermode() isn't defined in the !IS_ENABLED > case, so either I need to fake up a definition or use #ifdef. > > If I faked up a definition, I would want to assert, at build time, that > it isn't called. I don't think we can do: > > static void membarrier_sync_core_before_usermode() > { > BUILD_BUG_IF_REACHABLE(); > } Let's look at the context here: static void ipi_sync_core(void *info) { [....] membarrier_sync_core_before_usermode() } ^ this can be within #ifdef / #endif static int membarrier_private_expedited(int flags, int cpu_id) [...] if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE)) return -EINVAL; if (!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY)) return -EPERM; ipi_func = ipi_sync_core; All we need to make the line above work is to define an empty ipi_sync_core function in the #else case after the ipi_sync_core() function definition. Or am I missing your point ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com