FROMLIST: config: android-recommended: disable aio support

The aio interface adds substantial attack surface for a feature that's not
being exposed by Android at all.  It's unlikely that anyone is using the
kernel feature directly either.  This feature is rarely used even on
servers.  The glibc POSIX aio calls really use thread pools.  The lack of
widespread usage also means this is relatively poorly audited/tested.

The kernel's aio rarely provides performance benefits over using a thread
pool and is quite incomplete in terms of system call coverage along with
having edge cases where blocking can occur.  Part of the performance issue
is the fact that it only supports direct io, not buffered io.  The
existing API is considered fundamentally flawed and it's unlikely it will
be expanded, but rather replaced:

https://marc.info/?l=linux-aio&m=145255815216051&w=2

Since ext4 encryption means no direct io support, kernel aio isn't even
going to work properly on Android devices using file-based encryption.

Reviewed-at: https://android-review.googlesource.com/#/c/292158/

Link: http://lkml.kernel.org/r/1481113148-29204-1-git-send-email-amit.pundir@linaro.org


Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Cc: Rob Herring <rob.herring@linaro.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>