Re: [patch 2/2] Documentation/process: Add tip tree handbook

Thomas Gleixner
2018-11-07T17:44:17Z

On Wed, 7 Nov 2018, Thomas Gleixner wrote:

> Add a document to the subsystem/maintainer handbook section, which explains
> what the tip tree is, how it operates and what rules and expectations it
> has.

Peter asked me to add a section about locking comments. I added it and
forgot to refresh the patch before sending. Delta patch below.

Thanks,

tglx
---
--- a/Documentation/process/maintainer-tip.rst
+++ b/Documentation/process/maintainer-tip.rst
@@ -578,6 +578,29 @@ Sentences in comments start with a upper
usage of descriptive function names often replaces these tiny comments.
Apply common sense as always.

+
+Documenting locking requirements
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ Documenting locking requirements is a good thing, but comments are not
+ necessarily the best choice. Instead of writing::
+
+ /* Caller must hold foo->lock */
+ void func(struct foo *foo)
+ {
+ ...
+ }
+
+ Please use::
+
+ void func(struct foo *foo)
+ {
+ lockdep_assert_held(&foo->lock);
+ ...
+ }
+
+ The latter enables run time debugging when lockdep is enabled which
+ verifies that all callers hold the lock. Comments can't do that.
+

Bracket rules
^^^^^^^^^^^^^