cpumask: use work_on_cpu in acpi-cpufreq.c for read_measured_perf_ctrs

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 read_measured_perf_ctrs().

Basically splits off the work function from get_measured_perf which is
run on the designated cpu.  Moves definition of struct perf_cur out of
function local namespace, and is used as the work function argument.
References in get_measured_perf use values in the perf_cur struct.

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, 43 insertions, 40 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index 4e4f2b04dac2..06fcd8f9323c 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -245,6 +245,30 @@ static u32 get_cur_val(const struct cpumask *mask)
         return cmd.val;
 }
 
+struct perf_cur {
+        union {
+                struct {
+                        u32 lo;
+                        u32 hi;
+                } split;
+                u64 whole;
+        } aperf_cur, mperf_cur;
+};
+
+
+static long read_measured_perf_ctrs(void *_cur)
+{
+        struct perf_cur *cur = _cur;
+
+        rdmsr(MSR_IA32_APERF, cur->aperf_cur.split.lo, cur->aperf_cur.split.hi);
+        rdmsr(MSR_IA32_MPERF, cur->mperf_cur.split.lo, cur->mperf_cur.split.hi);
+
+        wrmsr(MSR_IA32_APERF, 0, 0);
+        wrmsr(MSR_IA32_MPERF, 0, 0);
+
+        return 0;
+}
+
 /*
  * Return the measured active (C0) frequency on this CPU since last call
  * to this function.
@@ -261,31 +285,12 @@ static u32 get_cur_val(const struct cpumask *mask)
 static unsigned int get_measured_perf(struct cpufreq_policy *policy,
                                       unsigned int cpu)
 {
-        union {
-                struct {
-                        u32 lo;
-                        u32 hi;
-                } split;
-                u64 whole;
-        } aperf_cur, mperf_cur;
-
-        cpumask_t saved_mask;
+        struct perf_cur cur;
         unsigned int perf_percent;
         unsigned int retval;
 
-        saved_mask = current->cpus_allowed;
-        set_cpus_allowed_ptr(current, &cpumask_of_cpu(cpu));
-        if (get_cpu() != cpu) {
-                /* We were not able to run on requested processor */
-                put_cpu();
+        if (!work_on_cpu(cpu, read_measured_perf_ctrs, &cur))
                 return 0;
-        }
-
-        rdmsr(MSR_IA32_APERF, aperf_cur.split.lo, aperf_cur.split.hi);
-        rdmsr(MSR_IA32_MPERF, mperf_cur.split.lo, mperf_cur.split.hi);
-
-        wrmsr(MSR_IA32_APERF, 0,0);
-        wrmsr(MSR_IA32_MPERF, 0,0);
 
 #ifdef __i386__
         /*
@@ -293,37 +298,39 @@ static unsigned int get_measured_perf(struct cpufreq_policy *policy,
          * Get an approximate value. Return failure in case we cannot get
          * an approximate value.
          */
-        if (unlikely(aperf_cur.split.hi || mperf_cur.split.hi)) {
+        if (unlikely(cur.aperf_cur.split.hi || cur.mperf_cur.split.hi)) {
                 int shift_count;
                 u32 h;
 
-                h = max_t(u32, aperf_cur.split.hi, mperf_cur.split.hi);
+                h = max_t(u32, cur.aperf_cur.split.hi, cur.mperf_cur.split.hi);
                 shift_count = fls(h);
 
-                aperf_cur.whole >>= shift_count;
-                mperf_cur.whole >>= shift_count;
+                cur.aperf_cur.whole >>= shift_count;
+                cur.mperf_cur.whole >>= shift_count;
         }
 
-        if (((unsigned long)(-1) / 100) < aperf_cur.split.lo) {
+        if (((unsigned long)(-1) / 100) < cur.aperf_cur.split.lo) {
                 int shift_count = 7;
-                aperf_cur.split.lo >>= shift_count;
-                mperf_cur.split.lo >>= shift_count;
+                cur.aperf_cur.split.lo >>= shift_count;
+                cur.mperf_cur.split.lo >>= shift_count;
         }
 
-        if (aperf_cur.split.lo && mperf_cur.split.lo)
-                perf_percent = (aperf_cur.split.lo * 100) / mperf_cur.split.lo;
+        if (cur.aperf_cur.split.lo && cur.mperf_cur.split.lo)
+                perf_percent = (cur.aperf_cur.split.lo * 100) /
+                                cur.mperf_cur.split.lo;
         else
                 perf_percent = 0;
 
 #else
-        if (unlikely(((unsigned long)(-1) / 100) < aperf_cur.whole)) {
+        if (unlikely(((unsigned long)(-1) / 100) < cur.aperf_cur.whole)) {
                 int shift_count = 7;
-                aperf_cur.whole >>= shift_count;
-                mperf_cur.whole >>= shift_count;
+                cur.aperf_cur.whole >>= shift_count;
+                cur.mperf_cur.whole >>= shift_count;
         }
 
-        if (aperf_cur.whole && mperf_cur.whole)
-                perf_percent = (aperf_cur.whole * 100) / mperf_cur.whole;
+        if (cur.aperf_cur.whole && cur.mperf_cur.whole)
+                perf_percent = (cur.aperf_cur.whole * 100) /
+                                cur.mperf_cur.whole;
         else
                 perf_percent = 0;
 
@@ -331,10 +338,6 @@ static unsigned int get_measured_perf(struct cpufreq_policy *policy,
 
         retval = per_cpu(drv_data, policy->cpu)->max_freq * perf_percent / 100;
 
-        put_cpu();
-        set_cpus_allowed_ptr(current, &saved_mask);
-
-        dprintk("cpu %d: performance percent %d\n", cpu, perf_percent);
         return retval;
 }
 
@@ -352,7 +355,7 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
         }
 
         cached_freq = data->freq_table[data->acpi_data->state].frequency;
-        freq = extract_freq(get_cur_val(&cpumask_of_cpu(cpu)), data);
+        freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
         if (freq != cached_freq) {
                 /*
                  * The dreaded BIOS frequency change behind our back.