cpumask: use work_on_cpu in acpi/cstate.c

Impact: use new cpumask API to reduce stack usage

Replace the saving of current->cpus_allowed and set_cpus_allowed_ptr() with
a work_on_cpu function for the acpi_processor_ffh_cstate_probe() function.

Basically splits acpi_processor_ffh_cstate_probe() into two functions, the
other being acpi_processor_ffh_cstate_probe_cpu which is the work function
run on the designated cpu.

Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 37 insertions, 33 deletions

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index c2502eb9aa83..cf5ec586f220 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -66,35 +66,15 @@ static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
 
 #define NATIVE_CSTATE_BEYOND_HALT       (2)
 
-int acpi_processor_ffh_cstate_probe(unsigned int cpu,
-                struct acpi_processor_cx *cx, struct acpi_power_register *reg)
+static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
 {
-        struct cstate_entry *percpu_entry;
-        struct cpuinfo_x86 *c = &cpu_data(cpu);
-
-        cpumask_t saved_mask;
-        int retval;
+        struct acpi_processor_cx *cx = _cx;
+        long retval;
         unsigned int eax, ebx, ecx, edx;
         unsigned int edx_part;
         unsigned int cstate_type; /* C-state type and not ACPI C-state type */
         unsigned int num_cstate_subtype;
 
-        if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF )
-                return -1;
-
-        if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
-                return -1;
-
-        percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
-        percpu_entry->states[cx->index].eax = 0;
-        percpu_entry->states[cx->index].ecx = 0;
-
-        /* Make sure we are running on right CPU */
-        saved_mask = current->cpus_allowed;
-        retval = set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
-        if (retval)
-                return -1;
-
         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
 
         /* Check whether this particular cx_type (in CST) is supported or not */
@@ -114,21 +94,45 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
                 retval = -1;
                 goto out;
         }
-        percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
-
-        /* Use the hint in CST */
-        percpu_entry->states[cx->index].eax = cx->address;
 
         if (!mwait_supported[cstate_type]) {
                 mwait_supported[cstate_type] = 1;
-                printk(KERN_DEBUG "Monitor-Mwait will be used to enter C-%d "
-                       "state\n", cx->type);
+                printk(KERN_DEBUG
+                        "Monitor-Mwait will be used to enter C-%d "
+                        "state\n", cx->type);
         }
-        snprintf(cx->desc, ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
-                 cx->address);
-
+        snprintf(cx->desc,
+                        ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
+                        cx->address);
 out:
-        set_cpus_allowed_ptr(current, &saved_mask);
+        return retval;
+}
+
+int acpi_processor_ffh_cstate_probe(unsigned int cpu,
+                struct acpi_processor_cx *cx, struct acpi_power_register *reg)
+{
+        struct cstate_entry *percpu_entry;
+        struct cpuinfo_x86 *c = &cpu_data(cpu);
+        long retval;
+
+        if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
+                return -1;
+
+        if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
+                return -1;
+
+        percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
+        percpu_entry->states[cx->index].eax = 0;
+        percpu_entry->states[cx->index].ecx = 0;
+
+        /* Make sure we are running on right CPU */
+
+        retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
+        if (retval == 0) {
+                /* Use the hint in CST */
+                percpu_entry->states[cx->index].eax = cx->address;
+                percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
+        }
         return retval;
 }
 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);