Solution 1:

Try Exercises in Functional Analysis by Constantin Costara and Dumitru Popa.

Solution 2:

The book M. Fabian, P. Habala, P. Hajek, V. Montesinos, V. Zizler: Banach Space Theory. The Basis of Linear and Nonlinear Analysis has plenty of exercises at the and of each chapter.

Google Books link, MR2766381 (2012h:46001), Zbl 1229.46001.

Solution 3:

There is the classic by Halmos, a problem book in Hilbert spaces. It is a GTM book so should be easy to find. Stein's Real Analysis and Functional Analysis might be also a good choice, if you want a broader flavor in analysis topics.