Subject: [PATCH rdma-next 1/5] RDMA/core: Provide getter and setter to access IB device name

From: Leon Romanovsky <[email-masked]>
Date: Thu, 20 Sep 2018 14:21:58 +0300

From: Leon Romanovsky <[email-masked]>

Prepare IB device name field to rename operation by ensuring that all
accesses to it are protected with lock and users don't see part of name.

The protection is done with global device_lock because it is used in
allocation and deallocation phases. At this stage, this lock is not
busy and easily can be moved to be per-device, once it will be needed.

Signed-off-by: Leon Romanovsky <[email-masked]>
---
 drivers/infiniband/core/device.c | 24 +++++++++++++++++++++++-
 include/rdma/ib_verbs.h          |  8 +++++++-
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 5a680a88aa87..3270cde6d806 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -170,6 +170,14 @@ static struct ib_device *__ib_device_get_by_name(const char *name)
 	return NULL;
 }

+void ib_device_get_name(struct ib_device *ibdev, char *name)
+{
+	down_read(&lists_rwsem);
+	strlcpy(name, ibdev->name, IB_DEVICE_NAME_MAX);
+	up_read(&lists_rwsem);
+}
+EXPORT_SYMBOL(ib_device_get_name);
+
 static int alloc_name(char *name)
 {
 	unsigned long *inuse;
@@ -202,6 +210,21 @@ static int alloc_name(char *name)
 	return 0;
 }

+int ib_device_alloc_name(struct ib_device *ibdev, const char *pattern)
+{
+	int ret = 0;
+
+	mutex_lock(&device_mutex);
+	strlcpy(ibdev->name, pattern, IB_DEVICE_NAME_MAX);
+	if (strchr(ibdev->name, '%'))
+		ret = alloc_name(ibdev->name);
+
+	mutex_unlock(&device_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(ib_device_alloc_name);
+
 static void ib_device_release(struct device *device)
 {
 	struct ib_device *dev = container_of(device, struct ib_device, dev);
@@ -499,7 +522,6 @@ int ib_register_device(struct ib_device *device,
 		ret = alloc_name(device->name);
 		if (ret)
 			goto out;
-	}

 	if (ib_device_check_mandatory(device)) {
 		ret = -EINVAL;
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index e764ed1f6025..66660e7b9854 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2260,6 +2260,11 @@ struct ib_device {
 	/* Do not access @dma_device directly from ULP nor from HW drivers. */
 	struct device                *dma_device;

+	/*
+	 * Do not access @name directly,
+	 * use ib_device_get_name()/ib_device_alloc_name()
+	 * and don't assume that it can't change after access.
+	 */
 	char                          name[IB_DEVICE_NAME_MAX];

 	struct list_head              event_handler_list;
@@ -2638,7 +2643,8 @@ struct ib_device *ib_alloc_device(size_t size);
 void ib_dealloc_device(struct ib_device *device);

 void ib_get_device_fw_str(struct ib_device *device, char *str);
-
+int ib_device_alloc_name(struct ib_device *ibdev, const char *pattern);
+void ib_device_get_name(struct ib_device *ibdev, char *name);
 int ib_register_device(struct ib_device *device,
 		       int (*port_callback)(struct ib_device *,
 					    u8, struct kobject *));