cdx: Introduce lock to protect controller ops

Add a mutex lock to prevent race between controller ops initiated by
the bus subsystem and the controller registration/unregistration.

Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://lore.kernel.org/r/20231017160505.10640-3-abhijit.gangurde@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/cdx/cdx.c b/drivers/cdx/cdx.c
index 0252fc92433d1e213717e8dfe30f664f4948481e..75760388f5e7edf5a8e3957df0f3cbe368016d03 100644 (file)
--- a/drivers/cdx/cdx.c
+++ b/drivers/cdx/cdx.c
@@ -72,6 +72,8 @@
 
 /* IDA for CDX controllers registered with the CDX bus */
 static DEFINE_IDA(cdx_controller_ida);
+/* Lock to protect controller ops */
+static DEFINE_MUTEX(cdx_controller_lock);
 
 static char *compat_node_name = "xlnx,versal-net-cdx";
 
@@ -396,6 +398,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
        if (!val)
                return -EINVAL;
 
+       mutex_lock(&cdx_controller_lock);
+
        /* Unregister all the devices on the bus */
        cdx_unregister_devices(&cdx_bus_type);
 
@@ -415,6 +419,8 @@ static ssize_t rescan_store(const struct bus_type *bus,
                put_device(&pd->dev);
        }
 
+       mutex_unlock(&cdx_controller_lock);
+
        return count;
 }
 static BUS_ATTR_WO(rescan);
@@ -538,12 +544,14 @@ int cdx_register_controller(struct cdx_controller *cdx)
                return ret;
        }
 
+       mutex_lock(&cdx_controller_lock);
        cdx->id = ret;
 
        /* Scan all the devices */
        if (cdx->ops->scan)
                cdx->ops->scan(cdx);
        cdx->controller_registered = true;
+       mutex_unlock(&cdx_controller_lock);
 
        return 0;
 }
@@ -554,9 +562,13 @@ void cdx_unregister_controller(struct cdx_controller *cdx)
        if (cdx->id >= MAX_CDX_CONTROLLERS)
                return;
 
+       mutex_lock(&cdx_controller_lock);
+
        cdx->controller_registered = false;
        device_for_each_child(cdx->dev, NULL, cdx_unregister_device);
        ida_free(&cdx_controller_ida, cdx->id);
+
+       mutex_unlock(&cdx_controller_lock);
 }
 EXPORT_SYMBOL_GPL(cdx_unregister_controller);