Kernel testing and regressions: an example

Kernel testing and regressions: an example

In any application the developers are expected to test code before they check it in. Because otherwise, why have a restriction of who can check in - you're not even sure it will compile. I confess to having checked in blind when it was a one-line fix (e.g dig back far enough in GIMP or GTK+), but for whole features?

But the Linux kernel doesn't work this way. For another example, look at my Source Specific Multicast bugs. The kernel had supposedly supported this feature for a while, in both IPv4 and IPv6 (they had the same bug, the incorrect logic was copied, still untested, when the IPv6 code was added) but when I tried to use it I found that it was broken, and worse, that it was broken in a way which left an easy kernel denial of service attack.

The person who wrote that code can't have tested it (any test code they tried would fail, mine certainly did). They may not even have tried to compile it. But it looked superficially OK, it didn't offend Linus and so it went straight into the kernel. In any other project that would be a serious procedural failure and heads would roll, in the Linux kernel it's business as usual. That's got to stop, and if Linus won't stop it, maybe the vendors, through people like davej will have to.