ice: ice_adapter: release xa entry on adapter allocation failure

When ice_adapter_new() fails, the reserved XArray entry created by
xa_insert() is not released. This causes subsequent insertions at
the same index to return -EBUSY, potentially leading to
NULL pointer dereferences.

Reorder the operations as suggested by Przemek Kitszel:
1. Check if adapter already exists (xa_load)
2. Reserve the XArray slot (xa_reserve)
3. Allocate the adapter (ice_adapter_new)
4. Store the adapter (xa_store)

Fixes: 0f0023c ("ice: do not init struct ice_adapter more times than needed")
Suggested-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20251001115336.1707-1-vulab@iscas.ac.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: ISCAS-Vulab

drivers/net/ethernet/intel/ice/ice_adapter.c

@@ -99,19 +99,21 @@ struct ice_adapter *ice_adapter_get(struct pci_dev *pdev)
 
 	index = ice_adapter_xa_index(pdev);
 	scoped_guard(mutex, &ice_adapters_mutex) {
-		err = xa_insert(&ice_adapters, index, NULL, GFP_KERNEL);
-		if (err == -EBUSY) {
-			adapter = xa_load(&ice_adapters, index);
+		adapter = xa_load(&ice_adapters, index);
+		if (adapter) {
 			refcount_inc(&adapter->refcount);
 			WARN_ON_ONCE(adapter->index != ice_adapter_index(pdev));
 			return adapter;
 		}
+		err = xa_reserve(&ice_adapters, index, GFP_KERNEL);
 		if (err)
 			return ERR_PTR(err);
 
 		adapter = ice_adapter_new(pdev);
-		if (!adapter)
+		if (!adapter) {
+			xa_release(&ice_adapters, index);
 			return ERR_PTR(-ENOMEM);
+		}
 		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
 	}
 	return adapter;