[PATCH] x86/smpboot: set topology CPU mask before use.

[ning . a . zhang]

From: Zhang Ning <ning.a.zh...@intel.com>

we detect topology CPU mask in tsc is used before it is set, it leads
to longer bootup time.

let's check the code.

smpboot.c:smp_callin()
     ---> calibarate.c:calibrate_delay()
          ---> tsc.c: calibrate_delay_is_known()
               ---> topology_core_cpumask(): read topology CPU mask
     ---> set_cpu_sibling_map(raw_smp_processor_id())
          ---> cpumask_set_cpu(cpu, topology_core_cpumask(cpu));

from the calling chain, we know topology CPU mask is used before it
actually set.

So move set_cpu_sibling_map before calibrate_delay.

Change-Id: I4eb8facb8751fe7aa2c6d2eac32437266d92ec00
Signed-off-by: Zhang Ning <ning.a.zh...@intel.com>
---
 arch/x86/kernel/smpboot.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 36171bcd91f8..acee1ca3ef43 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -181,6 +181,12 @@ static void smp_callin(void)
        smp_store_cpu_info(cpuid);
 
        /*
+        * This must be done before setting cpu_online_mask
+        * or calling notify_cpu_starting.
+        */
+       set_cpu_sibling_map(raw_smp_processor_id());
+
+       /*
         * Get our bogomips.
         * Update loops_per_jiffy in cpu_data. Previous call to
         * smp_store_cpu_info() stored a value that is close but not as
@@ -190,11 +196,7 @@ static void smp_callin(void)
        cpu_data(cpuid).loops_per_jiffy = loops_per_jiffy;
        pr_debug("Stack at about %p\n", &cpuid);
 
-       /*
-        * This must be done before setting cpu_online_mask
-        * or calling notify_cpu_starting.
-        */
-       set_cpu_sibling_map(raw_smp_processor_id());
+
        wmb();
 
        notify_cpu_starting(cpuid);
-- 
2.11.0