x86: Remove cpumask games in x86/kernel/cpu/intel_cacheinfo.c

Impact: remove cpumask_t from stack.

We should not try to save and restore cpus_allowed on current.

We can't use work_on_cpu() here, since it's in the hotplug cpu path
(if anyone else tries to get the hotplug lock from a workqueue we
could deadlock against them).

Fortunately, we can just use smp_call_function_single() since the
function can run from an interrupt.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@tv-sign.ru>

1 files changed, 19 insertions, 22 deletions

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 43ea612d3e9d..fb7f946cb65e 100644
--- a/arch/x86/kernel/cpu/intel_cacheinfo.c
+++ b/arch/x86/kernel/cpu/intel_cacheinfo.c
@@ -534,31 +534,16 @@ static void __cpuinit free_cache_attributes(unsigned int cpu)
         per_cpu(cpuid4_info, cpu) = NULL;
 }
 
-static int __cpuinit detect_cache_attributes(unsigned int cpu)
+static void get_cpu_leaves(void *_retval)
 {
-        struct _cpuid4_info     *this_leaf;
-        unsigned long           j;
-        int                     retval;
-        cpumask_t               oldmask;
-
-        if (num_cache_leaves == 0)
-                return -ENOENT;
-
-        per_cpu(cpuid4_info, cpu) = kzalloc(
-            sizeof(struct _cpuid4_info) * num_cache_leaves, GFP_KERNEL);
-        if (per_cpu(cpuid4_info, cpu) == NULL)
-                return -ENOMEM;
-
-        oldmask = current->cpus_allowed;
-        retval = set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
-        if (retval)
-                goto out;
+        int j, *retval = _retval, cpu = smp_processor_id();
 
         /* Do cpuid and store the results */
         for (j = 0; j < num_cache_leaves; j++) {
+                struct _cpuid4_info *this_leaf;
                 this_leaf = CPUID4_INFO_IDX(cpu, j);
-                retval = cpuid4_cache_lookup(j, this_leaf);
-                if (unlikely(retval < 0)) {
+                *retval = cpuid4_cache_lookup(j, this_leaf);
+                if (unlikely(*retval < 0)) {
                         int i;
 
                         for (i = 0; i < j; i++)
@@ -567,9 +552,21 @@ static int __cpuinit detect_cache_attributes(unsigned int cpu)
                 }
                 cache_shared_cpu_map_setup(cpu, j);
         }
-        set_cpus_allowed_ptr(current, &oldmask);
+}
+
+static int __cpuinit detect_cache_attributes(unsigned int cpu)
+{
+        int                     retval;
+
+        if (num_cache_leaves == 0)
+                return -ENOENT;
+
+        per_cpu(cpuid4_info, cpu) = kzalloc(
+            sizeof(struct _cpuid4_info) * num_cache_leaves, GFP_KERNEL);
+        if (per_cpu(cpuid4_info, cpu) == NULL)
+                return -ENOMEM;
 
-out:
+        smp_call_function_single(cpu, get_cpu_leaves, &retval, true);
         if (retval) {
                 kfree(per_cpu(cpuid4_info, cpu));
                 per_cpu(cpuid4_info, cpu) = NULL;