From: K Prateek Nayak Date: Wed, 9 Apr 2025 05:34:43 +0000 (+0000) Subject: sched/fair: Use READ_ONCE() to read sg->asym_prefer_cpu X-Git-Tag: v6.16-rc1~197^2~9 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=872aa4de18889be63317a8c0f2de71a3a01e487c;p=thirdparty%2Fkernel%2Flinux.git sched/fair: Use READ_ONCE() to read sg->asym_prefer_cpu Subsequent commits add the support to dynamically update the sched_group struct's "asym_prefer_cpu" member from a remote CPU. Use READ_ONCE() when reading the "sg->asym_prefer_cpu" to ensure load balancer always reads the latest value. Signed-off-by: K Prateek Nayak Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250409053446.23367-2-kprateek.nayak@amd.com --- diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0c19459c80422..5e1bd9e8464cd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10251,7 +10251,7 @@ sched_group_asym(struct lb_env *env, struct sg_lb_stats *sgs, struct sched_group (sgs->group_weight - sgs->idle_cpus != 1)) return false; - return sched_asym(env->sd, env->dst_cpu, group->asym_prefer_cpu); + return sched_asym(env->sd, env->dst_cpu, READ_ONCE(group->asym_prefer_cpu)); } /* One group has more than one SMT CPU while the other group does not */ @@ -10488,7 +10488,8 @@ static bool update_sd_pick_busiest(struct lb_env *env, case group_asym_packing: /* Prefer to move from lowest priority CPU's work */ - return sched_asym_prefer(sds->busiest->asym_prefer_cpu, sg->asym_prefer_cpu); + return sched_asym_prefer(READ_ONCE(sds->busiest->asym_prefer_cpu), + READ_ONCE(sg->asym_prefer_cpu)); case group_misfit_task: /*