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| author | Andi Kleen <ak@suse.de> | 2005-08-19 06:56:40 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-08-19 19:18:47 -0700 |
| commit | 1eecd73cce4e11ba9d67ad767f92069cfba7b589 (patch) | |
| tree | c72bdb38231e163df346ba118af821e4875c95bb | |
| parent | 5e5ec10499a00bf4ce3440d5a9e1a5a176c5a640 (diff) | |
| download | linux-1eecd73cce4e11ba9d67ad767f92069cfba7b589.tar.gz linux-1eecd73cce4e11ba9d67ad767f92069cfba7b589.tar.bz2 linux-1eecd73cce4e11ba9d67ad767f92069cfba7b589.zip | |
[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 <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | 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 index b15761ff4101..fa25e39fe54d 100644 --- 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(); } |