Couple of days ago I sent a patchlet for USB hub code to
The fix was about 10 lines big and
it would not deserve mentioning but for its amusing work and
It was known for a long time that the debouncing loop
was broken from the conception, but nobody did anything
to fix it. An incompetent programmer somewhere eventually
came up with a patch, which does not fix the algorithm,
but just short-circuits the loop instead, letting it to
proceed. This fixed it for people who were frustrated by
the original (broken) loop implementation.
The patch began to float around, and one day SuSE began
to ship it. Eventually, a gentleman from Khroatia came
to the linux-usb-devel and wrote "This patch fixes my
problem, SuSE ships it, so be so kind and include it in
the mainstream kernel at last."
This was sooo wrong on so many levels, that I felt
compelled to fix the darn thing. Also, I got some negative
lessons, which may be obvious to some, but perhaps my
elitism and snobism blinded me.
- Some time ago, if a person could formulate a patch
with correct argument order for diff, I would assume
he or she read the code, at least. It is NOT SO.
- (Corrolary: there is a swarm of garbage patches floating around).
- Lots of people mastered the skill of downloading and
applying patches without a foggiest understanding of
- Even big and respectable vendors do not read crap
which they ship with their kernels.
Regarding the last point, I'm not saying that
SuSE is particularly bad, or Red Hat is good in this
respect. We always review patches we ship. This should be
sufficient, right? Well, in case of the debounce loop,
the garbage patch floating on the 'Net was so small, that
it provided no context. It was pretty hard to tell from
three lines up and down what it actually did. I caught
it because I "own" the USB subsystem in Red Hat, so I am
somewhat familiar with the code. We also have owners
of other major subsystems, such as scsi (Doug), IDE (Alan & Arjan), filesystems (SCT & Al), processes/signals (DaveM/Alan), scheduler (Mingo), networking (DaveM).
zealously guard their territories from infiltration of
rogue code. But what if someone posts a patch for IEEE-1394 which fixes a problem on someone's box? Or same for ISDN?
Thankfuly, we have a gatekeeper (Arjan), who is good at
saying "no", but this is a personality. He may quit one day.
The answer is, of course, push everything through the
community, and resist additional patches as much as possible. The pressure to include is strong, however.
I remember a public outcry when we shipped 81 patch RPM
for 5.2 or something like that. Despite Arjan's valiant
efforts, we now ship about 300, and everyone appears
resigned to it. But that's not the limit. United Linux
pushes 800! Worse, Linus preaches vendor kernels in
interviews. I dunno where this is going to end,
I really don't.
Gloomy today, am I.
P.S. Do not download and apply crap patches without looking
at the code they are touching.