PCI: pciehp: Add hotplug_lock to serialize hotplug events

Today it is there is no protection around pciehp_enable_slot() and
pciehp_disable_slot() to ensure that they complete before another
hot-plug operation can be done on that particular slot.

This patch introduces the slot->hotplug_lock to ensure that any hotplug
operations (add / remove) complete before another hotplug event can begin
processing on that particular slot.

Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 53b58debc288..23b4bde8aad3 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -283,8 +283,11 @@ static int pciehp_probe(struct pcie_device *dev)
         slot = ctrl->slot;
         pciehp_get_adapter_status(slot, &occupied);
         pciehp_get_power_status(slot, &poweron);
-        if (occupied && pciehp_force)
+        if (occupied && pciehp_force) {
+                mutex_lock(&slot->hotplug_lock);
                 pciehp_enable_slot(slot);
+                mutex_unlock(&slot->hotplug_lock);
+        }
         /* If empty slot's power status is on, turn power off */
         if (!occupied && poweron && POWER_CTRL(ctrl))
                 pciehp_power_off_slot(slot);
@@ -328,10 +331,12 @@ static int pciehp_resume (struct pcie_device *dev)
 
         /* Check if slot is occupied */
         pciehp_get_adapter_status(slot, &status);
+        mutex_lock(&slot->hotplug_lock);
         if (status)
                 pciehp_enable_slot(slot);
         else
                 pciehp_disable_slot(slot);
+        mutex_unlock(&slot->hotplug_lock);
         return 0;
 }
 #endif /* PM */