dibs: Define dibs_client_ops and dibs_dev_ops

Move the device add() and remove() functions from ism_client to
dibs_client_ops and call add_dev()/del_dev() for ism devices and
dibs_loopback devices. dibs_client_ops->add_dev() = smcd_register_dev() for
the smc_dibs_client. This is the first step to handle ism and loopback
devices alike (as dibs devices) in the smc dibs client.

Define dibs_dev->ops and move smcd_ops->get_chid to
dibs_dev_ops->get_fabric_id() for ism and loopback devices. See below for
why this needs to be in the same patch as dibs_client_ops->add_dev().

The following changes contain intermediate steps, that will be obsoleted by
follow-on patches, once more functionality has been moved to dibs:

Use different smcd_ops and max_dmbs for ism and loopback. Follow-on patches
will change SMC-D to directly use dibs_ops instead of smcd_ops.

In smcd_register_dev() it is now necessary to identify a dibs_loopback
device before smcd_dev and smcd_ops->get_chid() are available. So provide
dibs_dev_ops->get_fabric_id() in this patch and evaluate it in
smc_ism_is_loopback().

Call smc_loopback_init() in smcd_register_dev() and call
smc_loopback_exit() in smcd_unregister_dev() to handle the functionality
that is still in smc_loopback. Follow-on patches will move all smc_loopback
code to dibs_loopback.

In smcd_[un]register_dev() use only ism device name, this will be replaced
by dibs device name by a follow-on patch.

End of changes with intermediate parts.

Allocate an smcd event workqueue for all dibs devices, although
dibs_loopback does not generate events.

Use kernel memory instead of devres memory for smcd_dev and smcd->conn.
Since commit a72178cfe855 ("net/smc: Fix dependency of SMC on ISM") an ism
device and its driver can have a longer lifetime than the smc module, so
smc should not rely on devres to free its resources [1]. It is now the
responsibility of the smc client to free smcd and smcd->conn for all dibs
devices, ism devices as well as loopback. Call client->ops->del_dev() for
all existing dibs devices in dibs_unregister_client(), so all device
related structures can be freed in the client.

When dibs_unregister_client() is called in the context of smc_exit() or
smc_core_reboot_event(), these functions have already called
smc_lgrs_shutdown() which calls smc_smcd_terminate_all(smcd) and sets
going_away. This is done a second time in smcd_unregister_dev(). This is
analogous to how smcr is handled in these functions, by calling first
smc_lgrs_shutdown() and then smc_ib_unregister_client() >
smc_ib_remove_dev(), so leave it that way. It may be worth investigating,
whether smc_lgrs_shutdown() is still required or useful.

Remove CONFIG_SMC_LO. CONFIG_DIBS_LO now controls whether a dibs loopback
device exists or not.

Link: https://www.kernel.org/doc/Documentation/driver-model/devres.txt [1]
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Reviewed-by: Mahanta Jambigi <mjambigi@linux.ibm.com>
Link: https://patch.msgid.link/20250918110500.1731261-8-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/dibs/dibs_main.c b/drivers/dibs/dibs_main.c
index a7e33be36158..f1cfa5849277 100644
--- a/drivers/dibs/dibs_main.c
+++ b/drivers/dibs/dibs_main.c
@@ -36,8 +36,10 @@ static struct dibs_dev_list dibs_dev_list = {
 
 int dibs_register_client(struct dibs_client *client)
 {
+	struct dibs_dev *dibs;
 	int i, rc = -ENOSPC;
 
+	mutex_lock(&dibs_dev_list.mutex);
 	mutex_lock(&clients_lock);
 	for (i = 0; i < MAX_DIBS_CLIENTS; ++i) {
 		if (!clients[i]) {
@@ -51,19 +53,37 @@ int dibs_register_client(struct dibs_client *client)
 	}
 	mutex_unlock(&clients_lock);
 
+	if (i < MAX_DIBS_CLIENTS) {
+		/* initialize with all devices that we got so far */
+		list_for_each_entry(dibs, &dibs_dev_list.list, list) {
+			dibs->priv[i] = NULL;
+			client->ops->add_dev(dibs);
+		}
+	}
+	mutex_unlock(&dibs_dev_list.mutex);
+
 	return rc;
 }
 EXPORT_SYMBOL_GPL(dibs_register_client);
 
 int dibs_unregister_client(struct dibs_client *client)
 {
+	struct dibs_dev *dibs;
 	int rc = 0;
 
+	mutex_lock(&dibs_dev_list.mutex);
+	list_for_each_entry(dibs, &dibs_dev_list.list, list) {
+		clients[client->id]->ops->del_dev(dibs);
+		dibs->priv[client->id] = NULL;
+	}
+
 	mutex_lock(&clients_lock);
 	clients[client->id] = NULL;
 	if (client->id + 1 == max_client)
 		max_client--;
 	mutex_unlock(&clients_lock);
+
+	mutex_unlock(&dibs_dev_list.mutex);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(dibs_unregister_client);
@@ -80,7 +100,15 @@ EXPORT_SYMBOL_GPL(dibs_dev_alloc);
 
 int dibs_dev_add(struct dibs_dev *dibs)
 {
+	int i;
+
 	mutex_lock(&dibs_dev_list.mutex);
+	mutex_lock(&clients_lock);
+	for (i = 0; i < max_client; ++i) {
+		if (clients[i])
+			clients[i]->ops->add_dev(dibs);
+	}
+	mutex_unlock(&clients_lock);
 	list_add(&dibs->list, &dibs_dev_list.list);
 	mutex_unlock(&dibs_dev_list.mutex);
 
@@ -90,7 +118,15 @@ EXPORT_SYMBOL_GPL(dibs_dev_add);
 
 void dibs_dev_del(struct dibs_dev *dibs)
 {
+	int i;
+
 	mutex_lock(&dibs_dev_list.mutex);
+	mutex_lock(&clients_lock);
+	for (i = 0; i < max_client; ++i) {
+		if (clients[i])
+			clients[i]->ops->del_dev(dibs);
+	}
+	mutex_unlock(&clients_lock);
 	list_del_init(&dibs->list);
 	mutex_unlock(&dibs_dev_list.mutex);
 }