diff options
Diffstat (limited to 'arch/x86/xen/spinlock.c')
| -rw-r--r-- | arch/x86/xen/spinlock.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c index 5601506f2dd..36a5141108d 100644 --- a/arch/x86/xen/spinlock.c +++ b/arch/x86/xen/spinlock.c @@ -187,7 +187,6 @@ static noinline int xen_spin_lock_slow(struct raw_spinlock *lock, bool irq_enabl struct xen_spinlock *prev; int irq = __get_cpu_var(lock_kicker_irq); int ret; - unsigned long flags; u64 start; /* If kicker interrupts not initialized yet, just spin */ @@ -199,16 +198,12 @@ static noinline int xen_spin_lock_slow(struct raw_spinlock *lock, bool irq_enabl /* announce we're spinning */ prev = spinning_lock(xl); - flags = __raw_local_save_flags(); - if (irq_enable) { - ADD_STATS(taken_slow_irqenable, 1); - raw_local_irq_enable(); - } - ADD_STATS(taken_slow, 1); ADD_STATS(taken_slow_nested, prev != NULL); do { + unsigned long flags; + /* clear pending */ xen_clear_irq_pending(irq); @@ -228,6 +223,12 @@ static noinline int xen_spin_lock_slow(struct raw_spinlock *lock, bool irq_enabl goto out; } + flags = __raw_local_save_flags(); + if (irq_enable) { + ADD_STATS(taken_slow_irqenable, 1); + raw_local_irq_enable(); + } + /* * Block until irq becomes pending. If we're * interrupted at this point (after the trylock but @@ -238,13 +239,15 @@ static noinline int xen_spin_lock_slow(struct raw_spinlock *lock, bool irq_enabl * pending. */ xen_poll_irq(irq); + + raw_local_irq_restore(flags); + ADD_STATS(taken_slow_spurious, !xen_test_irq_pending(irq)); } while (!xen_test_irq_pending(irq)); /* check for spurious wakeups */ kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq)); out: - raw_local_irq_restore(flags); unspinning_lock(xl, prev); spin_time_accum_blocked(start); @@ -323,8 +326,13 @@ static void xen_spin_unlock(struct raw_spinlock *lock) smp_wmb(); /* make sure no writes get moved after unlock */ xl->lock = 0; /* release lock */ - /* make sure unlock happens before kick */ - barrier(); + /* + * Make sure unlock happens before checking for waiting + * spinners. We need a strong barrier to enforce the + * write-read ordering to different memory locations, as the + * CPU makes no implied guarantees about their ordering. + */ + mb(); if (unlikely(xl->spinners)) xen_spin_unlock_slow(xl); |