calling mysql procedure return empty result
Basically 

'column1' 'column2' 'column3' is different than 'column1,column2,column3'

So, you must compare the whole string:

 BEGIN
IF (col_names  = 'column1,column2,column3')
THEN
.
.
.


If you want to compare each variable separately, then you must pass them separate in your procedure call:

Call:

call hussian('prstate','table_1','column1','column2','column3',1)


Procedure:

CREATE PROCEDURE hussain(IN src_col varchar(20), 
                         IN tblname varchar(100), 
                         IN col_names1 varchar(100), 
                         IN col_names2 varchar(100), 
                         IN col_names3 varchar(100), 
                         IN _leadid int)