tree c72bdb38231e163df346ba118af821e4875c95bb
parent 5e5ec10499a00bf4ce3440d5a9e1a5a176c5a640
author Andi Kleen <[EMAIL PROTECTED]> Fri, 19 Aug 2005 06:56:40 +0200
committer Linus Torvalds <[EMAIL PROTECTED]> Sat, 20 Aug 2005 09:18:47 -0700
[PATCH] x86_64: Fix race in TSC synchronization
Plug a race in TSC synchronization
We need to do tsc_sync_wait() before the CPU is set online to prevent
multiple CPUs from doing it in parallel - which won't work because TSC
sync has global unprotected state.
Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
arch/x86_64/kernel/smpboot.c | 15 ++++++++-------
1 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -492,6 +492,14 @@ void __cpuinit start_secondary(void)
*/
set_cpu_sibling_map(smp_processor_id());
+ /*
+ * Wait for TSC sync to not schedule things before.
+ * We still process interrupts, which could see an inconsistent
+ * time in that window unfortunately.
+ * Do this here because TSC sync has global unprotected state.
+ */
+ tsc_sync_wait();
+
/*
* We need to hold call_lock, so there is no inconsistency
* between the time smp_call_function() determines number of
@@ -509,13 +517,6 @@ void __cpuinit start_secondary(void)
per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
unlock_ipi_call_lock();
- mb();
-
- /* Wait for TSC sync to not schedule things before.
- We still process interrupts, which could see an inconsistent
- time in that window unfortunately. */
- tsc_sync_wait();
-
cpu_idle();
}
-
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