cpumask: convert struct cpuinfo_x86's llc_shared_map to cpumask_var_t

Impact: reduce kernel memory usage when CONFIG_CPUMASK_OFFSTACK=y

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 27 insertions, 8 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 76139506c3e4..d794d9483c56 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -94,7 +94,7 @@ struct cpuinfo_x86 {
         unsigned long           loops_per_jiffy;
 #ifdef CONFIG_SMP
         /* cpus sharing the last level cache: */
-        cpumask_t               llc_shared_map;
+        cpumask_var_t           llc_shared_map;
 #endif
         /* cpuid returned max cores value: */
         u16                      x86_max_cores;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 5a58a45ac1e3..d6427aa56966 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -329,6 +329,23 @@ notrace static void __cpuinit start_secondary(void *unused)
         cpu_idle();
 }
 
+#ifdef CONFIG_CPUMASK_OFFSTACK
+/* In this case, llc_shared_map is a pointer to a cpumask. */
+static inline void copy_cpuinfo_x86(struct cpuinfo_x86 *dst,
+                                    const struct cpuinfo_x86 *src)
+{
+        struct cpumask *llc = dst->llc_shared_map;
+        *dst = *src;
+        dst->llc_shared_map = llc;
+}
+#else
+static inline void copy_cpuinfo_x86(struct cpuinfo_x86 *dst,
+                                    const struct cpuinfo_x86 *src)
+{
+        *dst = *src;
+}
+#endif /* CONFIG_CPUMASK_OFFSTACK */
+
 /*
  * The bootstrap kernel entry code has set these up. Save them for
  * a given CPU
@@ -338,7 +355,7 @@ void __cpuinit smp_store_cpu_info(int id)
 {
         struct cpuinfo_x86 *c = &cpu_data(id);
 
-        *c = boot_cpu_data;
+        copy_cpuinfo_x86(c, &boot_cpu_data);
         c->cpu_index = id;
         if (id != 0)
                 identify_secondary_cpu(c);
@@ -362,15 +379,15 @@ void __cpuinit set_cpu_sibling_map(int cpu)
                                 cpumask_set_cpu(cpu, cpu_sibling_mask(i));
                                 cpumask_set_cpu(i, cpu_core_mask(cpu));
                                 cpumask_set_cpu(cpu, cpu_core_mask(i));
-                                cpumask_set_cpu(i, &c->llc_shared_map);
-                                cpumask_set_cpu(cpu, &o->llc_shared_map);
+                                cpumask_set_cpu(i, c->llc_shared_map);
+                                cpumask_set_cpu(cpu, o->llc_shared_map);
                         }
                 }
         } else {
                 cpumask_set_cpu(cpu, cpu_sibling_mask(cpu));
         }
 
-        cpumask_set_cpu(cpu, &c->llc_shared_map);
+        cpumask_set_cpu(cpu, c->llc_shared_map);
 
         if (current_cpu_data.x86_max_cores == 1) {
                 cpumask_copy(cpu_core_mask(cpu), cpu_sibling_mask(cpu));
@@ -381,8 +398,8 @@ void __cpuinit set_cpu_sibling_map(int cpu)
         for_each_cpu(i, cpu_sibling_setup_mask) {
                 if (per_cpu(cpu_llc_id, cpu) != BAD_APICID &&
                     per_cpu(cpu_llc_id, cpu) == per_cpu(cpu_llc_id, i)) {
-                        cpumask_set_cpu(i, &c->llc_shared_map);
-                        cpumask_set_cpu(cpu, &cpu_data(i).llc_shared_map);
+                        cpumask_set_cpu(i, c->llc_shared_map);
+                        cpumask_set_cpu(cpu, cpu_data(i).llc_shared_map);
                 }
                 if (c->phys_proc_id == cpu_data(i).phys_proc_id) {
                         cpumask_set_cpu(i, cpu_core_mask(cpu));
@@ -420,7 +437,7 @@ const struct cpumask *cpu_coregroup_mask(int cpu)
         if (sched_mc_power_savings || sched_smt_power_savings)
                 return cpu_core_mask(cpu);
         else
-                return &c->llc_shared_map;
+                return c->llc_shared_map;
 }
 
 static void impress_friends(void)
@@ -1039,8 +1056,10 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
         for_each_possible_cpu(i) {
                 alloc_cpumask_var(&per_cpu(cpu_sibling_map, i), GFP_KERNEL);
                 alloc_cpumask_var(&per_cpu(cpu_core_map, i), GFP_KERNEL);
+                alloc_cpumask_var(&cpu_data(i).llc_shared_map, GFP_KERNEL);
                 cpumask_clear(per_cpu(cpu_core_map, i));
                 cpumask_clear(per_cpu(cpu_sibling_map, i));
+                cpumask_clear(cpu_data(i).llc_shared_map);
         }
         set_cpu_sibling_map(0);