On Wed, 17 Aug 2011, Dave Martin wrote:
Acked-by = This patch is definitely right, or I fully agree with the patch and trust the author's judgement ("I will share responsibility for the correctness and appropriateness of this patch"). This implies Reviewed-by. Normally an ack shouldn't get added unless the acker is confident that the patch is adequately tested (where the level of testing deemed adequate depends on the complexity of the patch) Again, this may rely on judgement of the comptence of the author and the other reviewers.
Reviewed-by = This patch looks correct and appropriate and I judge it ok to merge, but I assume the author knows what they're doing, and I don't necessarily take responsibility for the change.
I think some aspects of the above two are mixed up.
Normally, ACK == acknowledgement i.e. "I conceptually agree with the patch", but that doesn't necessarily mean that it was reviewed thoroughly. In other words, this quite matches your definition, but does not imply a Reviewed-by, and that assumes the author knows what they're doing.
Reviewed-by means that you did review the patch content in details, whether or not the author knows what they're doing. A Reviewed-by obviously implies an Acked-by.
Nicolas