This release contains one ABI breakage fix (that had been introduced in 2.1.10, and strictly speaking this release breaks ABI again to make it compatible with 2.1.9 and less, please take a look at 18104973 for more details). Apart from that it contains some bug fixes, that grouped below.

And even though the return value for evbuffer_setcb() had been changed it should ABI compatible (anyway that function is in -compat.h header).

There is also one patch that introduce new functionality, this is 546a366c, to tune SO_RCVBUF/SO_SNDBUF in evdns, but one can count it as a bug-fix on the application level, since before you cannot tune this settings and hence you could stumble on problems.

P.S. please use dist archives, i.e. libevent-2.1.11-stable.tar.gz (not the sources generated by github automatically)