Generic Patch Inference

A key issue in maintaining Linux device drivers is the need to update drivers in response to evolutions in Linux internal libraries. Currently, there is little tool support for performing and documenting such changes. In this paper we present a tool, spdiff, that identifies common changes made in a set of pairs of files and their updated versions, and extracts a generic patch performing those changes. Library developers can use our tool to extract a generic patch based on the result of manually updating a few typical driver files, and then apply this generic patch to other drivers. Driver developers can use it to extract an abstract representation of the set of changes that others have made. Our experiments on recent changes in Linux show that the inferred generic patches are more concise than the corresponding patches found in commits to the Linux source tree while being safe with respect to the changes performed in the provided pairs of driver files.