From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx> We need to make sure interrupts are disabled while we're relying on the contents of the per-cpu lock_waiting values, otherwise an interrupt handler could come in, try to take some other lock, block, and overwrite our values. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx> --- arch/x86/xen/spinlock.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 4c46144..2ed5d05 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -98,6 +98,7 @@ static void xen_lock_spinning(struct arch_spinlock *lock, unsigned want) struct xen_lock_waiting *w = &__get_cpu_var(lock_waiting); int cpu = smp_processor_id(); u64 start; + unsigned long flags; /* If kicker interrupts not initialized yet, just spin */ if (irq == -1) @@ -105,6 +106,10 @@ static void xen_lock_spinning(struct arch_spinlock *lock, unsigned want) start = spin_time_start(); + /* Make sure interrupts are disabled to ensure that these + per-cpu values are not overwritten. */ + local_irq_save(flags); + w->want = want; w->lock = lock; @@ -139,6 +144,9 @@ static void xen_lock_spinning(struct arch_spinlock *lock, unsigned want) out: cpumask_clear_cpu(cpu, &waiting_cpus); w->lock = NULL; + + local_irq_restore(flags); + spin_time_accum_blocked(start); } PV_CALLEE_SAVE_REGS_THUNK(xen_lock_spinning); -- 1.7.6 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
