RDMA/srp: Rename SRP sysfs name after IB device rename trigger

SRP logic used device name and port index as symlink to relevant
kobject. If the IB device is renamed then the prior name will be re-used
by the next device plugged in and sysfs will panic as SRP will try to
re-use the same name.

mlx5_ib: Mellanox Connect-IB Infiniband driver v5.0-0
sysfs: cannot create duplicate filename '/class/infiniband_srp/srp-mlx5_0-1'
CPU: 3 PID: 1107 Comm: modprobe Not tainted 5.1.0-for-upstream-perf-2019-05-12_15-09-52-87 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0x5a/0x73
sysfs_warn_dup+0x58/0x70
sysfs_do_create_link_sd.isra.2+0xa3/0xb0
device_add+0x33f/0x660
srp_add_one+0x301/0x4f0 [ib_srp]
add_client_context+0x99/0xe0 [ib_core]
enable_device_and_get+0xd1/0x1b0 [ib_core]
ib_register_device+0x533/0x710 [ib_core]
? mutex_lock+0xe/0x30
__mlx5_ib_add+0x23/0x70 [mlx5_ib]
mlx5_add_device+0x4e/0xd0 [mlx5_core]
mlx5_register_interface+0x85/0xc0 [mlx5_core]
? 0xffffffffa0791000
do_one_initcall+0x4b/0x1cb
? kmem_cache_alloc_trace+0xc6/0x1d0
? do_init_module+0x22/0x21f
do_init_module+0x5a/0x21f
load_module+0x17f2/0x1ca0
? m_show+0x1c0/0x1c0
__do_sys_finit_module+0x94/0xe0
do_syscall_64+0x48/0x120
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f157cce10d9

The module load/unload sequence was used to trigger such kernel panic:
sudo modprobe ib_srp
sudo modprobe -r mlx5_ib
sudo modprobe -r mlx5_core
sudo modprobe mlx5_core

Have SRP track the name of the core device so that it can't have a name
collision.

Fixes: d21943dd19b5 ("RDMA/core: Implement IB device rename function")
Signed-off-by: Leon Romanovsky <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/device.c

···
 
 int ib_device_rename(struct ib_device *ibdev, const char *name)
 {
+	unsigned long index;
+	void *client_data;
 	int ret;
 
 	down_write(&devices_rwsem);
 	if (!strcmp(name, dev_name(&ibdev->dev))) {
-		ret = 0;
-		goto out;
+		up_write(&devices_rwsem);
+		return 0;
 	}
 
 	if (__ib_device_get_by_name(name)) {
-		ret = -EEXIST;
-		goto out;
+		up_write(&devices_rwsem);
+		return -EEXIST;
 	}
 
 	ret = device_rename(&ibdev->dev, name);
-	if (ret)
-		goto out;
+	if (ret) {
+		up_write(&devices_rwsem);
+		return ret;
+	}
+
 	strlcpy(ibdev->name, name, IB_DEVICE_NAME_MAX);
 	ret = rename_compat_devs(ibdev);
-out:
-	up_write(&devices_rwsem);
-	return ret;
+
+	downgrade_write(&devices_rwsem);
+	down_read(&ibdev->client_data_rwsem);
+	xan_for_each_marked(&ibdev->client_data, index, client_data,
+			    CLIENT_DATA_REGISTERED) {
+		struct ib_client *client = xa_load(&clients, index);
+
+		if (!client || !client->rename)
+			continue;
+
+		client->rename(ibdev, client_data);
+	}
+	up_read(&ibdev->client_data_rwsem);
+	up_read(&devices_rwsem);
+	return 0;
 }
 
 static int alloc_name(struct ib_device *ibdev, const char *name)

drivers/infiniband/ulp/srp/ib_srp.c

···
 
 static void srp_add_one(struct ib_device *device);
 static void srp_remove_one(struct ib_device *device, void *client_data);
+static void srp_rename_dev(struct ib_device *device, void *client_data);
 static void srp_recv_done(struct ib_cq *cq, struct ib_wc *wc);
 static void srp_handle_qp_err(struct ib_cq *cq, struct ib_wc *wc,
 		const char *opname);
···
 static struct ib_client srp_client = {
 	.name   = "srp",
 	.add    = srp_add_one,
-	.remove = srp_remove_one
+	.remove = srp_remove_one,
+	.rename = srp_rename_dev
 };
 
 static struct ib_sa_client srp_sa_client;
···
 	kfree(host);
 
 	return NULL;
+}
+
+static void srp_rename_dev(struct ib_device *device, void *client_data)
+{
+	struct srp_device *srp_dev = client_data;
+	struct srp_host *host, *tmp_host;
+
+	list_for_each_entry_safe(host, tmp_host, &srp_dev->dev_list, list) {
+		char name[IB_DEVICE_NAME_MAX + 8];
+
+		snprintf(name, sizeof(name), "srp-%s-%d",
+			 dev_name(&device->dev), host->port);
+		device_rename(&host->dev, name);
+	}
 }
 
 static void srp_add_one(struct ib_device *device)

include/rdma/ib_verbs.h

···
 	const char *name;
 	void (*add)   (struct ib_device *);
 	void (*remove)(struct ib_device *, void *client_data);
+	void (*rename)(struct ib_device *dev, void *client_data);
 
 	/* Returns the net_dev belonging to this ib_client and matching the
 	 * given parameters.