- first line should be a short, informative description of what a patch does;
- use imperative mood, as Kernel documentation says (starting at line 112):
Describe your changes in imperative mood, e.g. "make xyzzy do frotz" instead of "[This patch] makes xyzzy do frotz" or "[I] changed xyzzy to do frotz", as if you are giving orders to the codebase to change its behaviour.
- "Pro Git" gives similar advice:
It’s also a good idea to use the imperative present tense in these messages. In other words, use commands. Instead of “I added tests for” or "Adding tests for," use "Add tests for."