[PATCH] synchronize_tsc() fixes

- Move the tsc synchronisation variables into a struct, mark it __initdata

- local `realdelta' wants to be 64-bit

- Print the skew for negative skews, as well as for positive ones

- remove dead code

Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 33 insertions, 29 deletions

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 6f5fea05f1d..f948419c888 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -212,14 +212,20 @@ valid_k7:
  * then we print a warning if not, and always resync.
  */
 
-static atomic_t tsc_start_flag = ATOMIC_INIT(0);
-static atomic_t tsc_count_start = ATOMIC_INIT(0);
-static atomic_t tsc_count_stop = ATOMIC_INIT(0);
-static unsigned long long tsc_values[NR_CPUS];
+static struct {
+        atomic_t start_flag;
+        atomic_t count_start;
+        atomic_t count_stop;
+        unsigned long long values[NR_CPUS];
+} tsc __initdata = {
+        .start_flag = ATOMIC_INIT(0),
+        .count_start = ATOMIC_INIT(0),
+        .count_stop = ATOMIC_INIT(0),
+};
 
 #define NR_LOOPS 5
 
-static void __init synchronize_tsc_bp (void)
+static void __init synchronize_tsc_bp(void)
 {
         int i;
         unsigned long long t0;
@@ -233,7 +239,7 @@ static void __init synchronize_tsc_bp (void)
         /* convert from kcyc/sec to cyc/usec */
         one_usec = cpu_khz / 1000;
 
-        atomic_set(&tsc_start_flag, 1);
+        atomic_set(&tsc.start_flag, 1);
         wmb();
 
         /*
@@ -250,16 +256,16 @@ static void __init synchronize_tsc_bp (void)
                 /*
                  * all APs synchronize but they loop on '== num_cpus'
                  */
-                while (atomic_read(&tsc_count_start) != num_booting_cpus()-1)
+                while (atomic_read(&tsc.count_start) != num_booting_cpus()-1)
                         cpu_relax();
-                atomic_set(&tsc_count_stop, 0);
+                atomic_set(&tsc.count_stop, 0);
                 wmb();
                 /*
                  * this lets the APs save their current TSC:
                  */
-                atomic_inc(&tsc_count_start);
+                atomic_inc(&tsc.count_start);
 
-                rdtscll(tsc_values[smp_processor_id()]);
+                rdtscll(tsc.values[smp_processor_id()]);
                 /*
                  * We clear the TSC in the last loop:
                  */
@@ -269,56 +275,54 @@ static void __init synchronize_tsc_bp (void)
                 /*
                  * Wait for all APs to leave the synchronization point:
                  */
-                while (atomic_read(&tsc_count_stop) != num_booting_cpus()-1)
+                while (atomic_read(&tsc.count_stop) != num_booting_cpus()-1)
                         cpu_relax();
-                atomic_set(&tsc_count_start, 0);
+                atomic_set(&tsc.count_start, 0);
                 wmb();
-                atomic_inc(&tsc_count_stop);
+                atomic_inc(&tsc.count_stop);
         }
 
         sum = 0;
         for (i = 0; i < NR_CPUS; i++) {
                 if (cpu_isset(i, cpu_callout_map)) {
-                        t0 = tsc_values[i];
+                        t0 = tsc.values[i];
                         sum += t0;
                 }
         }
         avg = sum;
         do_div(avg, num_booting_cpus());
 
-        sum = 0;
         for (i = 0; i < NR_CPUS; i++) {
                 if (!cpu_isset(i, cpu_callout_map))
                         continue;
-                delta = tsc_values[i] - avg;
+                delta = tsc.values[i] - avg;
                 if (delta < 0)
                         delta = -delta;
                 /*
                  * We report bigger than 2 microseconds clock differences.
                  */
                 if (delta > 2*one_usec) {
-                        long realdelta;
+                        long long realdelta;
+
                         if (!buggy) {
                                 buggy = 1;
                                 printk("\n");
                         }
                         realdelta = delta;
                         do_div(realdelta, one_usec);
-                        if (tsc_values[i] < avg)
+                        if (tsc.values[i] < avg)
                                 realdelta = -realdelta;
 
-                        if (realdelta > 0)
-                                printk(KERN_INFO "CPU#%d had %ld usecs TSC "
+                        if (realdelta)
+                                printk(KERN_INFO "CPU#%d had %Ld usecs TSC "
                                         "skew, fixed it up.\n", i, realdelta);
                 }
-
-                sum += delta;
         }
         if (!buggy)
                 printk("passed.\n");
 }
 
-static void __init synchronize_tsc_ap (void)
+static void __init synchronize_tsc_ap(void)
 {
         int i;
 
@@ -327,20 +331,20 @@ static void __init synchronize_tsc_ap (void)
          * this gets called, so we first wait for the BP to
          * finish SMP initialization:
          */
-        while (!atomic_read(&tsc_start_flag))
+        while (!atomic_read(&tsc.start_flag))
                 cpu_relax();
 
         for (i = 0; i < NR_LOOPS; i++) {
-                atomic_inc(&tsc_count_start);
-                while (atomic_read(&tsc_count_start) != num_booting_cpus())
+                atomic_inc(&tsc.count_start);
+                while (atomic_read(&tsc.count_start) != num_booting_cpus())
                         cpu_relax();
 
-                rdtscll(tsc_values[smp_processor_id()]);
+                rdtscll(tsc.values[smp_processor_id()]);
                 if (i == NR_LOOPS-1)
                         write_tsc(0, 0);
 
-                atomic_inc(&tsc_count_stop);
-                while (atomic_read(&tsc_count_stop) != num_booting_cpus())
+                atomic_inc(&tsc.count_stop);
+                while (atomic_read(&tsc.count_stop) != num_booting_cpus())
                         cpu_relax();
         }
 }