1 files changed, 8 insertions, 6 deletions

diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 441c88262169..1c8a8816a402 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -9,6 +9,7 @@
 #include <linux/log2.h>
 #include <linux/gfp.h>
 #include <linux/slab.h>
+#include <linux/atomic.h>
 
 #include <asm/paravirt.h>
 #include <asm/qspinlock.h>
@@ -21,6 +22,7 @@
 
 static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
 static DEFINE_PER_CPU(char *, irq_name);
+static DEFINE_PER_CPU(atomic_t, xen_qlock_wait_nest);
 static bool xen_pvspin = true;
 
 static void xen_qlock_kick(int cpu)
@@ -39,25 +41,25 @@ static void xen_qlock_kick(int cpu)
  */
 static void xen_qlock_wait(u8 *byte, u8 val)
 {
-        unsigned long flags;
         int irq = __this_cpu_read(lock_kicker_irq);
+        atomic_t *nest_cnt = this_cpu_ptr(&xen_qlock_wait_nest);
 
         /* If kicker interrupts not initialized yet, just spin */
         if (irq == -1 || in_nmi())
                 return;
 
-        /* Guard against reentry. */
-        local_irq_save(flags);
+        /* Detect reentry. */
+        atomic_inc(nest_cnt);
 
-        /* If irq pending already clear it. */
-        if (xen_test_irq_pending(irq)) {
+        /* If irq pending already and no nested call clear it. */
+        if (atomic_read(nest_cnt) == 1 && xen_test_irq_pending(irq)) {
                 xen_clear_irq_pending(irq);
         } else if (READ_ONCE(*byte) == val) {
                 /* Block until irq becomes pending (or a spurious wakeup) */
                 xen_poll_irq(irq);
         }
 
-        local_irq_restore(flags);
+        atomic_dec(nest_cnt);
 }
 
 static irqreturn_t dummy_handler(int irq, void *dev_id)