SPI_finish - Man Page

int SPI_finish(void)

SPI_finish closes an existing connection to the SPI manager. You must call this function after completing the SPI operations needed during your C function's current invocation. You do not need to worry about making this happen, however, if you abort the transaction via elog(ERROR). In that case SPI will clean itself up automatically.

SPI_OK_FINISH

if properly disconnected

SPI_ERROR_UNCONNECTED

if called from an unconnected C function