review (XS) for 7033779: CodeCache::largest_free_block may need to hold the CodeCache lock

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/7033779

7033779: CodeCache::largest_free_block may need to hold the CodeCache lock
Reviewed-by:

CodeCache::largest_free_block may be called without the CodeCache_lock
being held which might result in crashes when the free list is being
updated.  The changes for 7025742 are the primary culprit but there
are other places where this was being done.  The fix is to acquire the
lock when needed.  I wasn't able to directly reproduce the original
crash so I just tested it by running the JVM a bit to make sure the
calls to largest_free_block continued to work correctly in both
contexts.