[$] A reference-count tracking infrastructure

Reference counts are a commonly used mechanism for tracking the life cycleof objects in a computing system. As long as every user of an objectcorrectly maintains its references by incrementing and decrementing thereference count, that object will persist for as long as itis neededand will be properly destroyed once the last user is done. The "correctly"in that sentence is important, though; things do not workas well in the presence of reference-counting errors. Networkingdeveloper Eric Dumazet is working on areference-count tracking system that could prove useful for findingthese errors in the networking subsystem and, someday, throughout the kernel.