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

[Thomas Gleixner]

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
 ^^^^^^^^^^^^^