PCI: hotplug: ACPI: Fix context refcounting in acpiphp_grab_context()

If context is not NULL in acpiphp_grab_context(), but the
is_going_away flag is set for the device's parent, the reference
counter of the context needs to be decremented before returning
NULL or the context will never be freed, so make that happen.

Fixes: edf5bf34d408 ("ACPI / dock: Use callback pointers from devices' ACPI hotplug contexts")
Reported-by: Vasily Averin <vvs@virtuozzo.com>
Cc: 3.15+ <stable@vger.kernel.org> # 3.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index b4c92ce..3365c93 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -122,13 +122,21 @@ static struct acpiphp_context *acpiphp_grab_context(struct acpi_device *adev)
        struct acpiphp_context *context;
 
        acpi_lock_hp_context();
+
        context = acpiphp_get_context(adev);
-       if (!context || context->func.parent->is_going_away) {
-               acpi_unlock_hp_context();
-               return NULL;
+       if (!context)
+               goto unlock;
+
+       if (context->func.parent->is_going_away) {
+               acpiphp_put_context(context);
+               context = NULL;
+               goto unlock;
        }
+
        get_bridge(context->func.parent);
        acpiphp_put_context(context);
+
+unlock:
        acpi_unlock_hp_context();
        return context;
 }