dibs: Define dibs loopback

The first stage of loopback-ism was implemented as part of the
SMC module [1]. Now that we have the dibs layer, provide access to a
dibs_loopback device to all dibs clients.

This is the first step of moving loopback-ism from net/smc/smc_loopback.*
to drivers/dibs/dibs_loopback.*. One global structure lo_dev is allocated
and added to the dibs devices. Follow-on patches will move functionality.

Same as smc_loopback, dibs_loopback is provided by a config option.
Note that there is no way to dynamically add or remove the loopback
device. That could be a future improvement.

When moving code to drivers/dibs, replace ism_ prefix with dibs_ prefix.
As this is mostly a move of existing code, copyright and authors are
unchanged.

Link: https://lore.kernel.org/lkml/20240428060738.60843-1-guwen@linux.alibaba.com/ [1]
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-7-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/dibs/dibs_main.c b/drivers/dibs/dibs_main.c
index 2f420e077417..a7e33be36158 100644
--- a/drivers/dibs/dibs_main.c
+++ b/drivers/dibs/dibs_main.c
@@ -15,6 +15,8 @@
 #include <linux/err.h>
 #include <linux/dibs.h>
 
+#include "dibs_loopback.h"
+
 MODULE_DESCRIPTION("Direct Internal Buffer Sharing class");
 MODULE_LICENSE("GPL");
 
@@ -96,14 +98,21 @@ EXPORT_SYMBOL_GPL(dibs_dev_del);
 
 static int __init dibs_init(void)
 {
+	int rc;
+
 	memset(clients, 0, sizeof(clients));
 	max_client = 0;
 
-	return 0;
+	rc = dibs_loopback_init();
+	if (rc)
+		pr_err("%s fails with %d\n", __func__, rc);
+
+	return rc;
 }
 
 static void __exit dibs_exit(void)
 {
+	dibs_loopback_exit();
 }
 
 module_init(dibs_init);