1 files changed, 32 insertions, 14 deletions

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 9eba29b46cb..26488487bc6 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -16,7 +16,6 @@
  */
 #include <linux/spinlock.h>
 #include <linux/kernel.h>
-#include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/nmi.h>
 #include <asm/tsc.h>
@@ -25,24 +24,24 @@
  * Entry/exit counters that make sure that both CPUs
  * run the measurement code at once:
  */
-static __cpuinitdata atomic_t start_count;
-static __cpuinitdata atomic_t stop_count;
+static atomic_t start_count;
+static atomic_t stop_count;
 
 /*
  * We use a raw spinlock in this exceptional case, because
  * we want to have the fastest, inlined, non-debug version
  * of a critical section, to be able to prove TSC time-warps:
  */
-static __cpuinitdata arch_spinlock_t sync_lock = __ARCH_SPIN_LOCK_UNLOCKED;
+static arch_spinlock_t sync_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 
-static __cpuinitdata cycles_t last_tsc;
-static __cpuinitdata cycles_t max_warp;
-static __cpuinitdata int nr_warps;
+static cycles_t last_tsc;
+static cycles_t max_warp;
+static int nr_warps;
 
 /*
  * TSC-warp measurement loop running on both CPUs:
  */
-static __cpuinit void check_tsc_warp(void)
+static void check_tsc_warp(unsigned int timeout)
 {
 	cycles_t start, now, prev, end;
 	int i;
@@ -51,9 +50,9 @@ static __cpuinit void check_tsc_warp(void)
 	start = get_cycles();
 	rdtsc_barrier();
 	/*
-	 * The measurement runs for 20 msecs:
+	 * The measurement runs for 'timeout' msecs:
 	 */
-	end = start + tsc_khz * 20ULL;
+	end = start + (cycles_t) tsc_khz * timeout;
 	now = start;
 
 	for (i = 0; ; i++) {
@@ -99,10 +98,29 @@ static __cpuinit void check_tsc_warp(void)
 }
 
 /*
+ * If the target CPU coming online doesn't have any of its core-siblings
+ * online, a timeout of 20msec will be used for the TSC-warp measurement
+ * loop. Otherwise a smaller timeout of 2msec will be used, as we have some
+ * information about this socket already (and this information grows as we
+ * have more and more logical-siblings in that socket).
+ *
+ * Ideally we should be able to skip the TSC sync check on the other
+ * core-siblings, if the first logical CPU in a socket passed the sync test.
+ * But as the TSC is per-logical CPU and can potentially be modified wrongly
+ * by the bios, TSC sync test for smaller duration should be able
+ * to catch such errors. Also this will catch the condition where all the
+ * cores in the socket doesn't get reset at the same time.
+ */
+static inline unsigned int loop_timeout(int cpu)
+{
+	return (cpumask_weight(cpu_core_mask(cpu)) > 1) ? 2 : 20;
+}
+
+/*
  * Source CPU calls into this - it waits for the freshly booted
  * target CPU to arrive and then starts the measurement:
  */
-void __cpuinit check_tsc_sync_source(int cpu)
+void check_tsc_sync_source(int cpu)
 {
 	int cpus = 2;
 
@@ -135,7 +153,7 @@ void __cpuinit check_tsc_sync_source(int cpu)
 	 */
 	atomic_inc(&start_count);
 
-	check_tsc_warp();
+	check_tsc_warp(loop_timeout(cpu));
 
 	while (atomic_read(&stop_count) != cpus-1)
 		cpu_relax();
@@ -168,7 +186,7 @@ void __cpuinit check_tsc_sync_source(int cpu)
 /*
  * Freshly booted CPUs call into this:
  */
-void __cpuinit check_tsc_sync_target(void)
+void check_tsc_sync_target(void)
 {
 	int cpus = 2;
 
@@ -183,7 +201,7 @@ void __cpuinit check_tsc_sync_target(void)
 	while (atomic_read(&start_count) != cpus)
 		cpu_relax();
 
-	check_tsc_warp();
+	check_tsc_warp(loop_timeout(smp_processor_id()));
 
 	/*
 	 * Ok, we are done: