From: Shrikanth Hegde Date: Fri, 15 May 2026 17:24:53 +0000 (+0530) Subject: topology: Introduce cpu_smt_mask for CONFIG_SCHED_SMT=n X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=815c5cb76a3e5dad4fc3911b9073591dc3a29282;p=thirdparty%2Fkernel%2Flinux.git topology: Introduce cpu_smt_mask for CONFIG_SCHED_SMT=n Define cpu_smt_mask in case of CONFIG_SCHED_SMT=n as cpumask_of that CPU. With that config, it is expected that kernel treats each CPU as individual core. Using cpumask_of(cpu) reflects that. This would help to get rid of the ifdeffery that is spread across the codebase since cpu_smt_mask is defined only in case of CONFIG_SCHED_SMT=y. Note: There is no arch today which defines cpu_smt_mask unconditionally. So likely defining the cpu_smt_mask shouldn't lead redefinition errors. Signed-off-by: Shrikanth Hegde Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Phil Auld Reviewed-by: Valentin Schneider Tested-by: K Prateek Nayak Link: https://patch.msgid.link/20260515172456.542799-2-sshegde@linux.ibm.com --- diff --git a/include/linux/topology.h b/include/linux/topology.h index 6575af39fd10f..709a2dcf4c738 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -230,11 +230,24 @@ static inline int cpu_to_mem(int cpu) #define topology_drawer_cpumask(cpu) cpumask_of(cpu) #endif -#if defined(CONFIG_SCHED_SMT) && !defined(cpu_smt_mask) +/* + * Defining cpu_smt_mask as cpumask_of that CPU helps to get + * rid of lot of ifdeffery all around the codebase in case of + * CONFIG_SCHED_SMT=n. It just means there are no other siblings, which + * is what is expected. + */ +#if defined(CONFIG_SCHED_SMT) +# if !defined(cpu_smt_mask) static inline const struct cpumask *cpu_smt_mask(int cpu) { return topology_sibling_cpumask(cpu); } +# endif +#else /* !CONFIG_SCHED_SMT */ +static inline const struct cpumask *cpu_smt_mask(int cpu) +{ + return cpumask_of(cpu); +} #endif #ifndef topology_is_primary_thread