x86: add smp_mb() before sending INVALIDATE_TLB_VECTOR
Impact: fix rare x2apic hang
On x86, x2apic mode accesses for sending IPI's don't have serializing
semantics. If the IPI receivner refers(in lock-free fashion) to some
memory setup by the sender, the need for smp_mb() before sending the
IPI becomes critical in x2apic mode.
Add the smp_mb() in native_flush_tlb_others() before sending the IPI.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/tlb_32.c b/arch/x86/kernel/tlb_32.c
index e00534b..f4049f3 100644
--- a/arch/x86/kernel/tlb_32.c
+++ b/arch/x86/kernel/tlb_32.c
@@ -154,6 +154,12 @@
flush_mm = mm;
flush_va = va;
cpus_or(flush_cpumask, cpumask, flush_cpumask);
+
+ /*
+ * Make the above memory operations globally visible before
+ * sending the IPI.
+ */
+ smp_mb();
/*
* We have to send the IPI only to
* CPUs affected.
diff --git a/arch/x86/kernel/tlb_64.c b/arch/x86/kernel/tlb_64.c
index dcbf7a1..8f919ca 100644
--- a/arch/x86/kernel/tlb_64.c
+++ b/arch/x86/kernel/tlb_64.c
@@ -183,6 +183,11 @@
cpus_or(f->flush_cpumask, cpumask, f->flush_cpumask);
/*
+ * Make the above memory operations globally visible before
+ * sending the IPI.
+ */
+ smp_mb();
+ /*
* We have to send the IPI only to
* CPUs affected.
*/