I help in staging and we get tons and tons of these cleanups.  I
decided to take a look at how bugs are introduced into staging.  I
sorted through everything with a Fixes tag and divided it into
"new code", "fixes" and "cleanups".

The initial driver upload only accounts for maybe a third of our bugs.
I was surprised this figure was so low.

Mechanical newbie patches are maybe 3-5% of our bugs.  A good chunk of
these were old patches that didn't go through the normal driver-devel
mailing list and review process.  Most of these bugs were detectable
using static analysis so in terms of bugs that make it into a released
version of the kernel the impact from these cleanups is tiny.

The majority of our bugs come from the maintainers doing complicated to
review cleanups.

Some people are over using the Fixes tag.  If the patch is removing
unused variables, then that's not a runtime bug but we should still use
a Fixes tag.  But if we're just silencing GCC false positives then we
shouldn't use a Fixes tag.

I also looked at how the bugs were found.  Probably in staging the bugs
are reported to the vendor instead of to the driver-devel list.  I don't
know if the vendors are adding Reported-by tags correctly...  Out of the
fixes that have a Reported-by tag, most bugs are found by auto builders
and static analysis.  Another large chunk are found by maintainers (one
maintainer adds a bug and a different maintainer notices it).  It's
probably between two and five times per year that a regular user gets a
Reported-by tag.

I'm going to attach my raw data but I don't know if it's too large for
the mailing list.

regards,
dan carpenter