too many nested calls to #Tcl_EvalObj (infinite loop?) ,got this error while executing a #tcl #recursive procedure..please tel me how to...

too many nested calls to #Tcl_EvalObj (infinite loop?) ,got this error
while executing a #tcl #recursive procedure..please tel me how to...

this proc is for traversing a hash map...and identify the connected nodes
proc search { search_var list_no } { global a;
set y $a($search_var)
if { [kernel_get_attribute $y property]=="flip_flop general"
} {
append list_no " " $y
search $y $list_no
}
set first [ lindex $list_no 0 ]
set last [ lindex $list_no [ expr [ llength $list_no ]
-1 ] ]
if { $first != " " } {
append $list_no " " $first
}
if { $last != " " } {
append $last " " $list_no
}
# puts "here"
} foreach i [array names a] { list $i $i search $i $i }