Using Redundancies to Find Errors

gsbarnes writes "Two Stanford researchers (Dawson Engler and Yichen Xie) have written a paper (pdf) showing that seemingly harmless redundant code is frequently a sign of not so harmless errors. Examples of redundant code: assigning a variable to itself, or dead code (code that is never reached). Some of their examples are obvious errors, some of them subtle. All are taken from a version of the Linux kernel (presumably they have already reported the bugs they found). Two interesting lessons: Apparently harmless mistakes often indicate serious troubles, so run lint and pay attention to its output. Also, in addition to its obvious practical uses, Linux provides a huge open codebase useful for researchers investigating questions about software engineering."

Comments

Here's a text link

[Anonymous Coward]

PDF usually crashes my computer (crappy adobe software). So here's a convenient text link!

http://216.239.37.100/search?q=cache:yuZKW8CjTqIC: www.stanford.edu/~engler/p401-xie.ps+&hl=en&ie=UTF -8

Re:Is this not Obvious

[gmack]

If only the story poster had actually read the paper.

They used a custom checker that finds these things much more effiectivly than lint.

I actually remember the flood of bug reports and kernel patches that toy of theirs generated the first few months they put it to use on the kernel.