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>

diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c
index 43ea612d3e9d81891dc6e630c33a9081ddc1a7ab..fb7f946cb65ec139e6ec9c5ada4900c757482df3 100644 (file)
--- 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;