I've been running static analysis using CoverityScan on
linux-next for 2 years with the aim to find bugs (and try to fix some) before they are merged into Linux. I have also been gathering the defect count data and tracking the defect trends:
As one can see from above, CoverityScan has found a considerable amount of defects and these are being steadily fixed by the Linux developer community. The encouraging fact is that the outstanding issues are reducing over time. Some of the spikes in the data are because of changes in the analysis that I'm running (e.g. getting more coverage), but even so, one can see a definite trend downwards in the total defects in the Kernel.
With static analysis, some of these reported defects are false positives or corner cases that are in fact impossible to occur in real life and I am slowly working through these and annotating them so they don't get reported in the defect count.
It must be also noted that over these two years the kernel has grown from around 14.6 million to 17.1 million lines of code so the defect count has dropped from 1 defect in every ~2100 lines to 1 defect in every ~3000 lines over the past 2 years. All in all, it is a remarkable improvement for such a large and complex codebase that is growing in size at such rate.
