Messages in this thread Patch in this message | | | From | "Joel Fernandes (Google)" <> | Subject | [RFC 4/5] sched/toplogy: Use smp_store_release() instead of rcu_assign_pointer | Date | Tue, 19 Feb 2019 23:08:26 -0500 |
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From: Joel Fernandes <joel@joelfernandes.org>
The scheduler's topology code seems to want to use rcu_assign_pointer() to initialize various pointers for no apparent reason.
With a guess that what was needed here is smp_store_release(), I am replacing it with that. This suppresses the new sparse errors caused by an annotation check I added to rcu_assign_pointer(). Let us avoid (ab)using RCU API and be explicit about what we want.
Fixes sparse errors: kernel//sched/topology.c:206:1: sparse: warning: symbol 'sched_energy_mutex' was not declared. Should it be static? kernel//sched/topology.c:207:6: sparse: warning: symbol 'sched_energy_update' was not declared. Should it be static? >> kernel//sched/topology.c:378:9: sparse: error: incompatible types in comparison expression (different address spaces) kernel//sched/topology.c:387:9: sparse: error: incompatible types in comparison expression (different address spaces) kernel//sched/topology.c:612:9: sparse: error: incompatible types in comparison expression (different address spaces) kernel//sched/topology.c:615:9: sparse: error: incompatible types in comparison expression (different address spaces) kernel//sched/topology.c:618:9: sparse: error: incompatible types in comparison expression (different address spaces) kernel//sched/topology.c:621:9: sparse: error: incompatible types in comparison expression (different address spaces)
Signed-off-by: Joel Fernandes <joel@joelfernandes.org> --- kernel/sched/topology.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 3f35ba1d8fde..e7a424d8de8e 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -375,7 +375,7 @@ static bool build_perf_domains(const struct cpumask *cpu_map) /* Attach the new list of performance domains to the root domain. */ tmp = rd->pd; - rcu_assign_pointer(rd->pd, pd); + smp_store_release(&rd->pd, pd); if (tmp) call_rcu(&tmp->rcu, destroy_perf_domain_rcu); @@ -384,7 +384,7 @@ static bool build_perf_domains(const struct cpumask *cpu_map) free: free_pd(pd); tmp = rd->pd; - rcu_assign_pointer(rd->pd, NULL); + smp_store_release(&rd->pd, NULL); if (tmp) call_rcu(&tmp->rcu, destroy_perf_domain_rcu); @@ -609,19 +609,19 @@ static void update_top_cache_domain(int cpu) sds = sd->shared; } - rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); + smp_store_release(&per_cpu(sd_llc, cpu), sd); per_cpu(sd_llc_size, cpu) = size; per_cpu(sd_llc_id, cpu) = id; - rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds); + smp_store_release(&per_cpu(sd_llc_shared, cpu), sds); sd = lowest_flag_domain(cpu, SD_NUMA); - rcu_assign_pointer(per_cpu(sd_numa, cpu), sd); + smp_store_release(&per_cpu(sd_numa, cpu), sd); sd = highest_flag_domain(cpu, SD_ASYM_PACKING); - rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd); + smp_store_release(&per_cpu(sd_asym_packing, cpu), sd); sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY); - rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd); + smp_store_release(&per_cpu(sd_asym_cpucapacity, cpu), sd); } /* @@ -668,7 +668,7 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) rq_attach_root(rq, rd); tmp = rq->sd; - rcu_assign_pointer(rq->sd, sd); + smp_store_release(&rq->sd, sd); dirty_sched_domain_sysctl(cpu); destroy_sched_domains(tmp); -- 2.21.0.rc0.258.g878e2cd30e-goog
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