[PATCH net-next 09/18] net/smc: introduce SMC-D loopback device

Wen Gu
2023-09-19T14:43:09Z

This patch introduces a kind of loopback device for SMC-D. The device
is created when SMC module is loaded and destroyed when the SMC module
is unloaded. The loopback device is a kernel device used only by the
SMC module and is not restricted by net namespace, so it can be used
for local inter-process or inter-container communication.

Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
---
net/smc/Makefile | 2 +-
net/smc/af_smc.c | 12 +++-
net/smc/smc_loopback.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++
net/smc/smc_loopback.h | 31 ++++++++++
4 files changed, 200 insertions(+), 2 deletions(-)
create mode 100644 net/smc/smc_loopback.c
create mode 100644 net/smc/smc_loopback.h

diff --git a/net/smc/Makefile b/net/smc/Makefile
index 875efcd..a8c3711 100644
--- a/net/smc/Makefile
+++ b/net/smc/Makefile
@@ -4,5 +4,5 @@ obj-$(CONFIG_SMC) += smc.o
obj-$(CONFIG_SMC_DIAG) += smc_diag.o
smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
-smc-y += smc_tracepoint.o
+smc-y += smc_tracepoint.o smc_loopback.o
smc-$(CONFIG_SYSCTL) += smc_sysctl.o
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 7eab600..bc4300e 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -53,6 +53,7 @@
#include "smc_stats.h"
#include "smc_tracepoint.h"
#include "smc_sysctl.h"
+#include "smc_loopback.h"

static DEFINE_MUTEX(smc_server_lgr_pending); /* serialize link group
* creation on server
@@ -3552,15 +3553,23 @@ static int __init smc_init(void)
goto out_sock;
}

+ rc = smc_loopback_init();
+ if (rc) {
+ pr_err("%s: smc_loopback_init fails with %d\n", __func__, rc);
+ goto out_ib;
+ }
+
rc = tcp_register_ulp(&smc_ulp_ops);
if (rc) {
pr_err("%s: tcp_ulp_register fails with %d\n", __func__, rc);
- goto out_ib;
+ goto out_lo;
}

static_branch_enable(&tcp_have_smc);
return 0;

+out_lo:
+ smc_loopback_exit();
out_ib:
smc_ib_unregister_client();
out_sock:
@@ -3598,6 +3607,7 @@ static void __exit smc_exit(void)
tcp_unregister_ulp(&smc_ulp_ops);
sock_unregister(PF_SMC);
smc_core_exit();
+ smc_loopback_exit();
smc_ib_unregister_client();
smc_ism_exit();
destroy_workqueue(smc_close_wq);
diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c
new file mode 100644
index 0000000..7d88856
--- /dev/null
+++ b/net/smc/smc_loopback.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Shared Memory Communications Direct over loopback device.
+ *
+ * Provide a SMC-D loopback dummy device.
+ *
+ * Copyright (c) 2022, Alibaba Inc.
+ *
+ * Author: Wen Gu <guwen@linux.alibaba.com>
+ * Tony Lu <tonylu@linux.alibaba.com>
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/types.h>
+#include <net/smc.h>
+
+#include "smc_ism.h"
+#include "smc_loopback.h"
+
+static const char smc_lo_dev_name[] = "smc_lo";
+static struct smc_lo_dev *lo_dev;
+
+static const struct smcd_ops lo_ops = {
+ .query_remote_gid = NULL,
+ .register_dmb = NULL,
+ .unregister_dmb = NULL,
+ .add_vlan_id = NULL,
+ .del_vlan_id = NULL,
+ .set_vlan_required = NULL,
+ .reset_vlan_required = NULL,
+ .signal_event = NULL,
+ .move_data = NULL,
+ .supports_v2 = NULL,
+ .get_system_eid = NULL,
+ .get_local_gid = NULL,
+ .get_chid = NULL,
+ .get_dev = NULL,
+};
+
+static struct smcd_dev *smcd_lo_alloc_dev(const struct smcd_ops *ops,
+ int max_dmbs)
+{
+ struct smcd_dev *smcd;
+
+ smcd = kzalloc(sizeof(*smcd), GFP_KERNEL);
+ if (!smcd)
+ return NULL;
+
+ smcd->conn = kcalloc(max_dmbs, sizeof(struct smc_connection *),
+ GFP_KERNEL);
+ if (!smcd->conn)
+ goto out_smcd;
+
+ smcd->ops = ops;
+
+ spin_lock_init(&smcd->lock);
+ spin_lock_init(&smcd->lgr_lock);
+ INIT_LIST_HEAD(&smcd->vlan);
+ INIT_LIST_HEAD(&smcd->lgr_list);
+ init_waitqueue_head(&smcd->lgrs_deleted);
+ return smcd;
+
+out_smcd:
+ kfree(smcd);
+ return NULL;
+}
+
+static int smcd_lo_register_dev(struct smc_lo_dev *ldev)
+{
+ struct smcd_dev *smcd;
+
+ smcd = smcd_lo_alloc_dev(&lo_ops, SMC_LODEV_MAX_DMBS);
+ if (!smcd)
+ return -ENOMEM;
+
+ ldev->smcd = smcd;
+ smcd->priv = ldev;
+
+ /* TODO:
+ * register smc_lo to smcd_dev list.
+ */
+ return 0;
+}
+
+static void smcd_lo_unregister_dev(struct smc_lo_dev *ldev)
+{
+ /* TODO:
+ * unregister smc_lo from smcd_dev list.
+ */
+}
+
+static void smc_lo_dev_release(struct device *dev)
+{
+ struct smc_lo_dev *ldev =
+ container_of(dev, struct smc_lo_dev, dev);
+ struct smcd_dev *smcd = ldev->smcd;
+
+ kfree(smcd->conn);
+ kfree(smcd);
+ kfree(ldev);
+}
+
+static int smc_lo_dev_init(struct smc_lo_dev *ldev)
+{
+ return smcd_lo_register_dev(ldev);
+}
+
+static int smc_lo_dev_probe(void)
+{
+ struct smc_lo_dev *ldev;
+ int ret;
+
+ ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
+ if (!ldev)
+ return -ENOMEM;
+
+ ldev->dev.parent = NULL;
+ ldev->dev.release = smc_lo_dev_release;
+ device_initialize(&ldev->dev);
+ dev_set_name(&ldev->dev, smc_lo_dev_name);
+
+ ret = smc_lo_dev_init(ldev);
+ if (ret)
+ goto free_dev;
+
+ lo_dev = ldev; /* global loopback device */
+ return 0;
+
+free_dev:
+ kfree(ldev);
+ return ret;
+}
+
+static void smc_lo_dev_exit(struct smc_lo_dev *ldev)
+{
+ smcd_lo_unregister_dev(ldev);
+}
+
+static void smc_lo_dev_remove(void)
+{
+ if (!lo_dev)
+ return;
+
+ smc_lo_dev_exit(lo_dev);
+ put_device(&lo_dev->dev); /* device_initialize in smc_lo_dev_probe */
+}
+
+int smc_loopback_init(void)
+{
+ return smc_lo_dev_probe();
+}
+
+void smc_loopback_exit(void)
+{
+ smc_lo_dev_remove();
+}
diff --git a/net/smc/smc_loopback.h b/net/smc/smc_loopback.h
new file mode 100644
index 0000000..0f7583c
--- /dev/null
+++ b/net/smc/smc_loopback.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Shared Memory Communications Direct over loopback device.
+ *
+ * Provide a SMC-D loopback dummy device.
+ *
+ * Copyright (c) 2022, Alibaba Inc.
+ *
+ * Author: Wen Gu <guwen@linux.alibaba.com>
+ * Tony Lu <tonylu@linux.alibaba.com>
+ *
+ */
+
+#ifndef _SMC_LOOPBACK_H
+#define _SMC_LOOPBACK_H
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <net/smc.h>
+
+#define SMC_LODEV_MAX_DMBS 5000
+
+struct smc_lo_dev {
+ struct smcd_dev *smcd;
+ struct device dev;
+};
+
+int smc_loopback_init(void);
+void smc_loopback_exit(void);
+
+#endif /* _SMC_LOOPBACK_H */
--
1.8.3.1