net: devlink: report cell size of shared buffers

Shared buffer allocation is usually done in cell increments.
Drivers will either round up the allocation or refuse the
configuration if it's not an exact multiple of cell size.
Drivers know exactly the cell size of shared buffer, so help
out users by providing this information in dumps.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_buffers.c

@@ -713,6 +713,7 @@ int mlxsw_sp_sb_pool_get(struct mlxsw_core *mlxsw_core,
 	pool_info->pool_type = (enum devlink_sb_pool_type) dir;
 	pool_info->size = mlxsw_sp_cells_bytes(mlxsw_sp, pr->size);
 	pool_info->threshold_type = (enum devlink_sb_threshold_type) pr->mode;
+	pool_info->cell_size = mlxsw_sp->sb->cell_size;
 	return 0;
 }
 

drivers/net/ethernet/netronome/nfp/nfp_shared_buf.c

@@ -48,6 +48,7 @@ int nfp_shared_buf_pool_get(struct nfp_pf *pf, unsigned int sb, u16 pool_index,
 	pool_info->pool_type = le32_to_cpu(get_data.pool_type);
 	pool_info->threshold_type = le32_to_cpu(get_data.threshold_type);
 	pool_info->size = le32_to_cpu(get_data.size) * unit_size;
+	pool_info->cell_size = unit_size;
 
 	return 0;
 }

include/net/devlink.h

@@ -62,6 +62,7 @@ struct devlink_sb_pool_info {
 	enum devlink_sb_pool_type pool_type;
 	u32 size;
 	enum devlink_sb_threshold_type threshold_type;
+	u32 cell_size;
 };
 
 /**

include/uapi/linux/devlink.h

@@ -300,6 +300,8 @@ enum devlink_attr {
 	DEVLINK_ATTR_INFO_VERSION_NAME,		/* string */
 	DEVLINK_ATTR_INFO_VERSION_VALUE,	/* string */
 
+	DEVLINK_ATTR_SB_POOL_CELL_SIZE,		/* u32 */
+
 	/* add new attributes above here, update the policy in devlink.c */
 
 	__DEVLINK_ATTR_MAX,

net/core/devlink.c

@@ -932,6 +932,9 @@ static int devlink_nl_sb_pool_fill(struct sk_buff *msg, struct devlink *devlink,
 	if (nla_put_u8(msg, DEVLINK_ATTR_SB_POOL_THRESHOLD_TYPE,
 		       pool_info.threshold_type))
 		goto nla_put_failure;
+	if (nla_put_u32(msg, DEVLINK_ATTR_SB_POOL_CELL_SIZE,
+			pool_info.cell_size))
+		goto nla_put_failure;
 
 	genlmsg_end(msg, hdr);
 	return 0;