Open source software depends on collaborative effort but many contributions are lost because of the often adversarial process. How can reviewers be turned into mentors?

1. Taking the Fear Out of
Contributing
Stephen Hemminger
shemminger@vyatta.com

2. Code Quality

3. “Publicly making fun of people is half
the fun of open source programming.
In fact the main reason to eschew
programming in closed environments
is that you can't embarrass people in
public.”
– Linus Torvalds

4. What manager's want

5. Why do people contribute?
● Learn
● Altruism
● Fun
● Fame & Fortune
● Solve problems

6. What Maintainers say they do
Maintainer Maintainer
Project
Developer Mailing
List next Linux
Reviewers

7. What developers see
Linus
Linux
ME Kernel
Mailing
List

8. “It's entirely possible that the current
user could be replaced by RCU
and/or seqlocks, and we could get rid
of brlocks entirely.”
– Linus Torvalds (Mar 9 2003)

9. 2 days later...
2 weeks later...
2 years later...

10. What I learned
● Encouragement and feedback
– Pat Mochel
– Linus
– David Miller
– Paul McKenney
● Learned Internals
● Encouragement from employer

11. Advice to developers
Have:
F. ollow rules
U. nderstand feedback
N. egotiate

12. Main causes of failure
Things that make maintainers:
M. assive
A. rrogance
D. ivisive

13. Patch Acceptance
Massive
from netdev patchwork
100%
75%
Acceptance
50%
25%
0%
256 1024 4096 16384 65536 262144
128 512 2048 8192 32768 131072
Patch size

14. Arrogance
ar·ro·gant (r-gnt)
adj.
1. Having or displaying a sense of overbearing self-
worth or self-importance.
2. Marked by or arising from a feeling or
assumption of one's superiority toward others: an
arrogant contempt for the weak.

15. Divisive Changes
● Proprietary
● Incompatible
● Reinvention
● Ugly

16. Glossophobia

18. Evaluation
● Be prepared
● Active Listening
● Sandwich technique
● Focus on 2 or 3 items

19. Troll free zone
● Be genuine
● Evaluate presentation not person
● Personalize Language
● Directed feedback

20. Lessons Learned
● Risk = Reward
● Practice makes perfect
● Words matter
● Evaluation causes growth

21. Alternative Evaluation Styles
Toastmasters™ Linux™ Kernel
● Tell and Sell ● Fire and Forget
● Q&A ● Email Threads
● Group: ● Delegate:
– Voice – Style
– Gestures – Locking
– ...
– API
– ...

22. What is mentoring?

23. Bozeman and Feeney (2007) define mentoring
as “a process for the informal transmission of
knowledge, social capital, and the psychosocial
support perceived by the recipient as relevant
to work, career, or professional development;
mentoring entails informal communication,
usually face-to-face and during a sustained
period of time, between a person who is
perceived to have greater relevant knowledge,
wisdom, or experience (the mentor) and a
person who is perceived to have less (the
protègè).”

25. Virtual Tunnel Interface

26. Finding a Mentor
● Local
● Company
● Kernel mentors mailing list
http://kernelnewbies.org/KernelMentors

27. Role of Mentor
● Process mentoring
● Shoulder to cry on
● Local advocate
● Cheerleader

28. For maintainers
● Emphasize good review
● Assign mentors for new people?
● Track contribution status – patchwork
● Delegate review roles
● Encourage friendly dialogue
● Evaluate review process

29. Ideas
● Teach reviewing
– Documentation/ReviewingPatches?
– get_reviewers.pl?
● Document kernel semantics
– More lessons like RCU?
– Interactive tutorials

30. Thank you