devlink: Add health buffer support

Devlink health buffer is a mechanism to pass descriptors between drivers
and devlink. The API allows the driver to add objects, object pair,
value array (nested attributes), value and name.

Driver can use this API to fill the buffers in a format which can be
translated by the devlink to the netlink message.

In order to fulfill it, an internal buffer descriptor is defined. This
will hold the data and metadata per each attribute and by used to pass
actual commands to the netlink.

This mechanism will be later used in devlink health for dump and diagnose
data store by the drivers.
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Reviewed-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/devlink.h

@@ -423,6 +423,8 @@ struct devlink_region;
 
 typedef void devlink_snapshot_data_dest_t(const void *data);
 
+struct devlink_health_buffer;
+
 struct devlink_ops {
 	int (*reload)(struct devlink *devlink, struct netlink_ext_ack *extack);
 	int (*port_type_set)(struct devlink_port *devlink_port,
@@ -584,6 +586,22 @@ int devlink_region_snapshot_create(struct devlink_region *region, u64 data_len,
 				   u8 *data, u32 snapshot_id,
 				   devlink_snapshot_data_dest_t *data_destructor);
 
+int devlink_health_buffer_nest_start(struct devlink_health_buffer *buffer,
+				     int attrtype);
+void devlink_health_buffer_nest_end(struct devlink_health_buffer *buffer);
+void devlink_health_buffer_nest_cancel(struct devlink_health_buffer *buffer);
+int devlink_health_buffer_put_object_name(struct devlink_health_buffer *buffer,
+					  char *name);
+int devlink_health_buffer_put_value_u8(struct devlink_health_buffer *buffer,
+				       u8 value);
+int devlink_health_buffer_put_value_u32(struct devlink_health_buffer *buffer,
+					u32 value);
+int devlink_health_buffer_put_value_u64(struct devlink_health_buffer *buffer,
+					u64 value);
+int devlink_health_buffer_put_value_string(struct devlink_health_buffer *buffer,
+					   char *name);
+int devlink_health_buffer_put_value_data(struct devlink_health_buffer *buffer,
+					 void *data, int len);
 #else
 
 static inline struct devlink *devlink_alloc(const struct devlink_ops *ops,
@@ -844,6 +862,64 @@ devlink_region_snapshot_create(struct devlink_region *region, u64 data_len,
 	return 0;
 }
 
+static inline int
+devlink_health_buffer_nest_start(struct devlink_health_buffer *buffer,
+				 int attrtype)
+{
+	return 0;
+}
+
+static inline void
+devlink_health_buffer_nest_end(struct devlink_health_buffer *buffer)
+{
+}
+
+static inline void
+devlink_health_buffer_nest_cancel(struct devlink_health_buffer *buffer)
+{
+}
+
+static inline int
+devlink_health_buffer_put_object_name(struct devlink_health_buffer *buffer,
+				      char *name)
+{
+	return 0;
+}
+
+static inline int
+devlink_health_buffer_put_value_u8(struct devlink_health_buffer *buffer,
+				   u8 value)
+{
+	return 0;
+}
+
+static inline int
+devlink_health_buffer_put_value_u32(struct devlink_health_buffer *buffer,
+				    u32 value)
+{
+	return 0;
+}
+
+static inline int
+devlink_health_buffer_put_value_u64(struct devlink_health_buffer *buffer,
+				    u64 value)
+{
+	return 0;
+}
+
+static inline int
+devlink_health_buffer_put_value_string(struct devlink_health_buffer *buffer,
+				       char *name)
+{
+	return 0;
+}
+
+static inline int
+devlink_health_buffer_put_value_data(struct devlink_health_buffer *buffer,
+				     void *data, int len)
+{
+	return 0;
+}
 #endif
 
 #endif /* _NET_DEVLINK_H_ */

include/uapi/linux/devlink.h

@@ -285,6 +285,14 @@ enum devlink_attr {
 	DEVLINK_ATTR_REGION_CHUNK_ADDR,         /* u64 */
 	DEVLINK_ATTR_REGION_CHUNK_LEN,          /* u64 */
 
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT,		/* nested */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_PAIR,		/* nested */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_NAME,		/* string */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE,	/* nested */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_ARRAY,	/* nested */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,	/* u8 */
+	DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,	/* dynamic */
+
 	/* add new attributes above here, update the policy in devlink.c */
 
 	__DEVLINK_ATTR_MAX,

net/core/devlink.c

@@ -3597,6 +3597,507 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb,
 	return 0;
 }
 
+#define DEVLINK_HEALTH_BUFFER_SIZE (4096 - GENL_HDRLEN)
+#define DEVLINK_HEALTH_BUFFER_DATA_SIZE (DEVLINK_HEALTH_BUFFER_SIZE / 2)
+#define DEVLINK_HEALTH_SIZE_TO_BUFFERS(size) DIV_ROUND_UP(size, DEVLINK_HEALTH_BUFFER_DATA_SIZE)
+#define DEVLINK_HEALTH_BUFFER_MAX_CHUNK 1024
+
+struct devlink_health_buffer {
+	void *data;
+	u64 offset;
+	u64 bytes_left;
+	u64 bytes_left_metadata;
+	u64 max_nested_depth;
+	u64 curr_nest;
+};
+
+struct devlink_health_buffer_desc {
+	int attrtype;
+	u16 len;
+	u8 nla_type;
+	u8 nest_end;
+	int value[0];
+};
+
+static void
+devlink_health_buffers_reset(struct devlink_health_buffer **buffers_list,
+			     u64 num_of_buffers)
+{
+	u64 i;
+
+	for (i = 0; i < num_of_buffers; i++) {
+		memset(buffers_list[i]->data, 0, DEVLINK_HEALTH_BUFFER_SIZE);
+		buffers_list[i]->offset = 0;
+		buffers_list[i]->bytes_left = DEVLINK_HEALTH_BUFFER_DATA_SIZE;
+		buffers_list[i]->bytes_left_metadata =
+			DEVLINK_HEALTH_BUFFER_DATA_SIZE;
+		buffers_list[i]->max_nested_depth = 0;
+		buffers_list[i]->curr_nest = 0;
+	}
+}
+
+static void
+devlink_health_buffers_destroy(struct devlink_health_buffer **buffers_list,
+			       u64 size);
+
+static struct devlink_health_buffer **
+devlink_health_buffers_create(u64 size)
+{
+	struct devlink_health_buffer **buffers_list;
+	u64 num_of_buffers = DEVLINK_HEALTH_SIZE_TO_BUFFERS(size);
+	u64 i;
+
+	buffers_list = kcalloc(num_of_buffers,
+			       sizeof(struct devlink_health_buffer *),
+			       GFP_KERNEL);
+	if (!buffers_list)
+		return NULL;
+
+	for (i = 0; i < num_of_buffers; i++) {
+		struct devlink_health_buffer *buffer;
+		void *data;
+
+		buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
+		data = kzalloc(DEVLINK_HEALTH_BUFFER_SIZE, GFP_KERNEL);
+		if (!buffer || !data) {
+			kfree(buffer);
+			kfree(data);
+			goto buffers_cleanup;
+		}
+		buffers_list[i] = buffer;
+		buffer->data = data;
+	}
+	devlink_health_buffers_reset(buffers_list, num_of_buffers);
+
+	return buffers_list;
+
+buffers_cleanup:
+	devlink_health_buffers_destroy(buffers_list, --i);
+	kfree(buffers_list);
+	return NULL;
+}
+
+static void
+devlink_health_buffers_destroy(struct devlink_health_buffer **buffers_list,
+			       u64 num_of_buffers)
+{
+	u64 i;
+
+	for (i = 0; i < num_of_buffers; i++) {
+		kfree(buffers_list[i]->data);
+		kfree(buffers_list[i]);
+	}
+}
+
+void
+devlink_health_buffer_offset_inc(struct devlink_health_buffer *buffer,
+				 int len)
+{
+	buffer->offset += len;
+}
+
+/* In order to store a nest, need two descriptors, for start and end */
+#define DEVLINK_HEALTH_BUFFER_NEST_SIZE (sizeof(struct devlink_health_buffer_desc) * 2)
+
+int devlink_health_buffer_verify_len(struct devlink_health_buffer *buffer,
+				     int len, int metadata_len)
+{
+	if (len > DEVLINK_HEALTH_BUFFER_DATA_SIZE)
+		return -EINVAL;
+
+	if (buffer->bytes_left < len ||
+	    buffer->bytes_left_metadata < metadata_len)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static struct devlink_health_buffer_desc *
+devlink_health_buffer_get_desc_from_offset(struct devlink_health_buffer *buffer)
+{
+	return buffer->data + buffer->offset;
+}
+
+int
+devlink_health_buffer_nest_start(struct devlink_health_buffer *buffer,
+				 int attrtype)
+{
+	struct devlink_health_buffer_desc *desc;
+	int err;
+
+	err = devlink_health_buffer_verify_len(buffer, 0,
+					       DEVLINK_HEALTH_BUFFER_NEST_SIZE);
+	if (err)
+		return err;
+
+	if (attrtype != DEVLINK_ATTR_HEALTH_BUFFER_OBJECT &&
+	    attrtype != DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_PAIR &&
+	    attrtype != DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE &&
+	    attrtype != DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_ARRAY)
+		return -EINVAL;
+
+	desc = devlink_health_buffer_get_desc_from_offset(buffer);
+
+	desc->attrtype = attrtype;
+	buffer->bytes_left_metadata -= DEVLINK_HEALTH_BUFFER_NEST_SIZE;
+	devlink_health_buffer_offset_inc(buffer, sizeof(*desc));
+
+	buffer->curr_nest++;
+	buffer->max_nested_depth = max(buffer->max_nested_depth,
+				       buffer->curr_nest);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_nest_start);
+
+enum devlink_health_buffer_nest_end_cancel {
+	DEVLINK_HEALTH_BUFFER_NEST_END = 1,
+	DEVLINK_HEALTH_BUFFER_NEST_CANCEL,
+};
+
+static void
+devlink_health_buffer_nest_end_cancel(struct devlink_health_buffer *buffer,
+				      enum devlink_health_buffer_nest_end_cancel nest)
+{
+	struct devlink_health_buffer_desc *desc;
+
+	WARN_ON(!buffer->curr_nest);
+	buffer->curr_nest--;
+
+	desc = devlink_health_buffer_get_desc_from_offset(buffer);
+	desc->nest_end = nest;
+	devlink_health_buffer_offset_inc(buffer, sizeof(*desc));
+}
+
+void devlink_health_buffer_nest_end(struct devlink_health_buffer *buffer)
+{
+	devlink_health_buffer_nest_end_cancel(buffer,
+					      DEVLINK_HEALTH_BUFFER_NEST_END);
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_nest_end);
+
+void devlink_health_buffer_nest_cancel(struct devlink_health_buffer *buffer)
+{
+	devlink_health_buffer_nest_end_cancel(buffer,
+					      DEVLINK_HEALTH_BUFFER_NEST_CANCEL);
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_nest_cancel);
+
+int
+devlink_health_buffer_put_object_name(struct devlink_health_buffer *buffer,
+				      char *name)
+{
+	struct devlink_health_buffer_desc *desc;
+	int err;
+
+	err = devlink_health_buffer_verify_len(buffer, strlen(name) + 1,
+					       sizeof(*desc));
+	if (err)
+		return err;
+
+	desc = devlink_health_buffer_get_desc_from_offset(buffer);
+	desc->attrtype = DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_NAME;
+	desc->nla_type = NLA_NUL_STRING;
+	desc->len = strlen(name) + 1;
+	memcpy(&desc->value, name, desc->len);
+	devlink_health_buffer_offset_inc(buffer, sizeof(*desc) + desc->len);
+
+	buffer->bytes_left_metadata -= sizeof(*desc);
+	buffer->bytes_left -= (strlen(name) + 1);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_object_name);
+
+static int
+devlink_health_buffer_put_value(struct devlink_health_buffer *buffer,
+				u8 nla_type, void *value, int len)
+{
+	struct devlink_health_buffer_desc *desc;
+	int err;
+
+	err = devlink_health_buffer_verify_len(buffer, len, sizeof(*desc));
+	if (err)
+		return err;
+
+	desc = devlink_health_buffer_get_desc_from_offset(buffer);
+	desc->attrtype = DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA;
+	desc->nla_type = nla_type;
+	desc->len = len;
+	memcpy(&desc->value, value, len);
+	devlink_health_buffer_offset_inc(buffer, sizeof(*desc) + desc->len);
+
+	buffer->bytes_left_metadata -= sizeof(*desc);
+	buffer->bytes_left -= len;
+
+	return 0;
+}
+
+int
+devlink_health_buffer_put_value_u8(struct devlink_health_buffer *buffer,
+				   u8 value)
+{
+	int err;
+
+	err = devlink_health_buffer_put_value(buffer, NLA_U8, &value,
+					      sizeof(value));
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_value_u8);
+
+int
+devlink_health_buffer_put_value_u32(struct devlink_health_buffer *buffer,
+				    u32 value)
+{
+	int err;
+
+	err = devlink_health_buffer_put_value(buffer, NLA_U32, &value,
+					      sizeof(value));
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_value_u32);
+
+int
+devlink_health_buffer_put_value_u64(struct devlink_health_buffer *buffer,
+				    u64 value)
+{
+	int err;
+
+	err = devlink_health_buffer_put_value(buffer, NLA_U64, &value,
+					      sizeof(value));
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_value_u64);
+
+int
+devlink_health_buffer_put_value_string(struct devlink_health_buffer *buffer,
+				       char *name)
+{
+	int err;
+
+	if (strlen(name) + 1 > DEVLINK_HEALTH_BUFFER_MAX_CHUNK)
+		return -EINVAL;
+
+	err = devlink_health_buffer_put_value(buffer, NLA_NUL_STRING, name,
+					      strlen(name) + 1);
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_value_string);
+
+int
+devlink_health_buffer_put_value_data(struct devlink_health_buffer *buffer,
+				     void *data, int len)
+{
+	int err;
+
+	if (len > DEVLINK_HEALTH_BUFFER_MAX_CHUNK)
+		return -EINVAL;
+
+	err = devlink_health_buffer_put_value(buffer, NLA_BINARY, data, len);
+	if (err)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devlink_health_buffer_put_value_data);
+
+static int
+devlink_health_buffer_fill_data(struct sk_buff *skb,
+				struct devlink_health_buffer_desc *desc)
+{
+	int err = -EINVAL;
+
+	switch (desc->nla_type) {
+	case NLA_U8:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,
+				 *(u8 *)desc->value);
+		break;
+	case NLA_U32:
+		err = nla_put_u32(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,
+				  *(u32 *)desc->value);
+		break;
+	case NLA_U64:
+		err = nla_put_u64_64bit(skb,
+					DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,
+					*(u64 *)desc->value, DEVLINK_ATTR_PAD);
+		break;
+	case NLA_NUL_STRING:
+		err = nla_put_string(skb,
+				     DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,
+				     (char *)&desc->value);
+		break;
+	case NLA_BINARY:
+		err = nla_put(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA,
+			      desc->len, (void *)&desc->value);
+		break;
+	}
+
+	return err;
+}
+
+static int
+devlink_health_buffer_fill_type(struct sk_buff *skb,
+				struct devlink_health_buffer_desc *desc)
+{
+	int err = -EINVAL;
+
+	switch (desc->nla_type) {
+	case NLA_U8:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,
+				 NLA_U8);
+		break;
+	case NLA_U32:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,
+				 NLA_U32);
+		break;
+	case NLA_U64:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,
+				 NLA_U64);
+		break;
+	case NLA_NUL_STRING:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,
+				 NLA_NUL_STRING);
+		break;
+	case NLA_BINARY:
+		err = nla_put_u8(skb, DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_TYPE,
+				 NLA_BINARY);
+		break;
+	}
+
+	return err;
+}
+
+static inline struct devlink_health_buffer_desc *
+devlink_health_buffer_get_next_desc(struct devlink_health_buffer_desc *desc)
+{
+	return (void *)&desc->value + desc->len;
+}
+
+static int
+devlink_health_buffer_prepare_skb(struct sk_buff *skb,
+				  struct devlink_health_buffer *buffer)
+{
+	struct devlink_health_buffer_desc *last_desc, *desc;
+	struct nlattr **buffer_nlattr;
+	int err;
+	int i = 0;
+
+	buffer_nlattr = kcalloc(buffer->max_nested_depth,
+				sizeof(*buffer_nlattr), GFP_KERNEL);
+	if (!buffer_nlattr)
+		return -EINVAL;
+
+	last_desc = devlink_health_buffer_get_desc_from_offset(buffer);
+	desc = buffer->data;
+	while (desc != last_desc) {
+		switch (desc->attrtype) {
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT:
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_PAIR:
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE:
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_ARRAY:
+			buffer_nlattr[i] = nla_nest_start(skb, desc->attrtype);
+			if (!buffer_nlattr[i])
+				goto nla_put_failure;
+			i++;
+			break;
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_VALUE_DATA:
+			err = devlink_health_buffer_fill_data(skb, desc);
+			if (err)
+				goto nla_put_failure;
+			err = devlink_health_buffer_fill_type(skb, desc);
+			if (err)
+				goto nla_put_failure;
+			break;
+		case DEVLINK_ATTR_HEALTH_BUFFER_OBJECT_NAME:
+			err = nla_put_string(skb, desc->attrtype,
+					     (char *)&desc->value);
+			if (err)
+				goto nla_put_failure;
+			break;
+		default:
+			WARN_ON(!desc->nest_end);
+			WARN_ON(i <= 0);
+			if (desc->nest_end == DEVLINK_HEALTH_BUFFER_NEST_END)
+				nla_nest_end(skb, buffer_nlattr[--i]);
+			else
+				nla_nest_cancel(skb, buffer_nlattr[--i]);
+			break;
+		}
+		desc = devlink_health_buffer_get_next_desc(desc);
+	}
+
+	return 0;
+
+nla_put_failure:
+	kfree(buffer_nlattr);
+	return err;
+}
+
+static int
+devlink_health_buffer_snd(struct genl_info *info,
+			  enum devlink_command cmd, int flags,
+			  struct devlink_health_buffer **buffers_array,
+			  u64 num_of_buffers)
+{
+	struct sk_buff *skb;
+	struct nlmsghdr *nlh;
+	void *hdr;
+	int err;
+	u64 i;
+
+	for (i = 0; i < num_of_buffers; i++) {
+		/* Skip buffer if driver did not fill it up with any data */
+		if (!buffers_array[i]->offset)
+			continue;
+
+		skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+		if (!skb)
+			return -ENOMEM;
+
+		hdr = genlmsg_put(skb, info->snd_portid, info->snd_seq,
+				  &devlink_nl_family, NLM_F_MULTI, cmd);
+		if (!hdr)
+			goto nla_put_failure;
+
+		err = devlink_health_buffer_prepare_skb(skb, buffers_array[i]);
+		if (err)
+			goto nla_put_failure;
+
+		genlmsg_end(skb, hdr);
+		err = genlmsg_reply(skb, info);
+		if (err)
+			return err;
+	}
+
+	skb = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+	nlh = nlmsg_put(skb, info->snd_portid, info->snd_seq,
+			NLMSG_DONE, 0, flags | NLM_F_MULTI);
+	err = genlmsg_reply(skb, info);
+	if (err)
+		return err;
+
+	return 0;
+
+nla_put_failure:
+	err = -EIO;
+	nlmsg_free(skb);
+	return err;
+}
+
 static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
 	[DEVLINK_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING },
 	[DEVLINK_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING },