pciehp: Add missing memory barrier

Fix the possible race condition between pcie_isr() and pciehp_write_cmd()
because of the lack of memory barrier.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by:  Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 51a5055f6965..19eba2a2f746 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -279,6 +279,7 @@ static int pcie_write_cmd(struct slot *slot, u16 cmd, u16 mask)
         slot_ctrl |= ((cmd & mask) | CMD_CMPL_INTR_ENABLE);
 
         ctrl->cmd_busy = 1;
+        smp_mb();
         retval = pciehp_writew(ctrl, SLOTCTRL, slot_ctrl);
         if (retval)
                 err("%s: Cannot write to SLOTCTRL register\n", __func__);
@@ -759,6 +760,7 @@ static irqreturn_t pcie_isr(int irq, void *dev_id)
         /* Check Command Complete Interrupt Pending */
         if (intr_loc & CMD_COMPLETED) {
                 ctrl->cmd_busy = 0;
+                smp_mb();
                 wake_up_interruptible(&ctrl->queue);
         }