[PATCH net-next 04/14] net/dibs: Register smc as dibs_client

Alexandra Winter
2025-09-05T14:54:44Z

Formally register smc as dibs client. Functionality will be moved by
follow-on patches from ism_client to dibs_client until eventually
ism_client can be removed.
As DIBS is only a shim layer without any dependencies, we can depend SMC
on DIBS without adding indirect dependencies. A follow-on patch will
remove dependency of SMC on ISM.

Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
---
arch/s390/configs/debug_defconfig | 1 +
arch/s390/configs/defconfig | 1 +
include/linux/dibs.h | 24 ++++++++++++++++++++-
net/dibs/dibs_main.c | 35 +++++++++++++++++++++++++++++++
net/smc/Kconfig | 2 +-
net/smc/smc_ism.c | 6 ++++++
6 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig
index 5e616bc988ac..7bc54f053a3b 100644
--- a/arch/s390/configs/debug_defconfig
+++ b/arch/s390/configs/debug_defconfig
@@ -120,6 +120,7 @@ CONFIG_UNIX=y
CONFIG_UNIX_DIAG=m
CONFIG_XFRM_USER=m
CONFIG_NET_KEY=m
+CONFIG_DIBS=y
CONFIG_SMC_DIAG=m
CONFIG_SMC_LO=y
CONFIG_INET=y
diff --git a/arch/s390/configs/defconfig b/arch/s390/configs/defconfig
index 094599cdaf4d..4bf6f3311f7d 100644
--- a/arch/s390/configs/defconfig
+++ b/arch/s390/configs/defconfig
@@ -111,6 +111,7 @@ CONFIG_UNIX=y
CONFIG_UNIX_DIAG=m
CONFIG_XFRM_USER=m
CONFIG_NET_KEY=m
+CONFIG_DIBS=y
CONFIG_SMC_DIAG=m
CONFIG_SMC_LO=y
CONFIG_INET=y
diff --git a/include/linux/dibs.h b/include/linux/dibs.h
index 3f4175aaa732..5c432699becb 100644
--- a/include/linux/dibs.h
+++ b/include/linux/dibs.h
@@ -33,10 +33,32 @@
* clients.
*/

+/* DIBS client
+ * -----------
+ */
#define MAX_DIBS_CLIENTS 8
-
struct dibs_client {
+ /* client name for logging and debugging purposes */
const char *name;
+ /* client index - provided and used by dibs layer */
+ u8 id;
};

+/* Functions to be called by dibs clients:
+ */
+/**
+ * dibs_register_client() - register a client with dibs layer
+ * @client: this client
+ *
+ * Return: zero on success.
+ */
+int dibs_register_client(struct dibs_client *client);
+/**
+ * dibs_unregister_client() - unregister a client with dibs layer
+ * @client: this client
+ *
+ * Return: zero on success.
+ */
+int dibs_unregister_client(struct dibs_client *client);
+
#endif /* _DIBS_H */
diff --git a/net/dibs/dibs_main.c b/net/dibs/dibs_main.c
index 68e189932fcf..a5d2be9c3246 100644
--- a/net/dibs/dibs_main.c
+++ b/net/dibs/dibs_main.c
@@ -20,6 +20,41 @@ MODULE_LICENSE("GPL");
/* use an array rather a list for fast mapping: */
static struct dibs_client *clients[MAX_DIBS_CLIENTS];
static u8 max_client;
+static DEFINE_MUTEX(clients_lock);
+
+int dibs_register_client(struct dibs_client *client)
+{
+ int i, rc = -ENOSPC;
+
+ mutex_lock(&clients_lock);
+ for (i = 0; i < MAX_DIBS_CLIENTS; ++i) {
+ if (!clients[i]) {
+ clients[i] = client;
+ client->id = i;
+ if (i == max_client)
+ max_client++;
+ rc = 0;
+ break;
+ }
+ }
+ mutex_unlock(&clients_lock);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(dibs_register_client);
+
+int dibs_unregister_client(struct dibs_client *client)
+{
+ int rc = 0;
+
+ mutex_lock(&clients_lock);
+ clients[client->id] = NULL;
+ if (client->id + 1 == max_client)
+ max_client--;
+ mutex_unlock(&clients_lock);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(dibs_unregister_client);

static int __init dibs_init(void)
{
diff --git a/net/smc/Kconfig b/net/smc/Kconfig
index ba5e6a2dd2fd..40dd60c1d23f 100644
--- a/net/smc/Kconfig
+++ b/net/smc/Kconfig
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
config SMC
tristate "SMC socket protocol family"
- depends on INET && INFINIBAND
+ depends on INET && INFINIBAND && DIBS
depends on m || ISM != m
help
SMC-R provides a "sockets over RDMA" solution making use of
diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
index 503a9f93b392..a7a965e3c0ce 100644
--- a/net/smc/smc_ism.c
+++ b/net/smc/smc_ism.c
@@ -18,6 +18,7 @@
#include "smc_pnet.h"
#include "smc_netlink.h"
#include "linux/ism.h"
+#include "linux/dibs.h"

struct smcd_dev_list smcd_dev_list = {
.list = LIST_HEAD_INIT(smcd_dev_list.list),
@@ -42,6 +43,9 @@ static struct ism_client smc_ism_client = {
.handle_irq = smcd_handle_irq,
};
#endif
+static struct dibs_client smc_dibs_client = {
+ .name = "SMC-D",
+};

static void smc_ism_create_system_eid(void)
{
@@ -623,11 +627,13 @@ int smc_ism_init(void)
#if IS_ENABLED(CONFIG_ISM)
rc = ism_register_client(&smc_ism_client);
#endif
+ rc = dibs_register_client(&smc_dibs_client);
return rc;
}

void smc_ism_exit(void)
{
+ dibs_unregister_client(&smc_dibs_client);
#if IS_ENABLED(CONFIG_ISM)
ism_unregister_client(&smc_ism_client);
#endif
--
2.48.1