Both are right, but it's a bit tricky to construct a while-condition doing a readline and exiting at false.

I'd rather use an explicit last with condition inside the body.

use strict;
use warnings;
use feature 'say';


while ( $_= <DATA>, chomp, $_) {
    say;
}

__DATA__
3
1
0
2
[download]

-->

3
1
[download]

(NB: Iterators don't necessarily loop over lines where they need to chomp, <update see here>)