asm-generic: qrwlock: Document the spinlock fairness requirements

palmer-dabbelt · palmer-dabbelt · commit 493e2ba27635 · 2022-05-11T11:49:54.000-07:00
I could only find the fairness requirements documented as the C code,
this calls them out in a comment just to be a bit more explicit.

Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Palmer Dabbelt &lt;palmer@rivosinc.com&gt;
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
@@ -2,6 +2,10 @@
 /*
  * Queue read/write lock
  *
+ * These use generic atomic and locking routines, but depend on a fair spinlock
+ * implementation in order to be fair themselves.  The implementation in
+ * asm-generic/spinlock.h meets these requirements.
+ *
  * (C) Copyright 2013-2014 Hewlett-Packard Development Company, L.P.
  *
  * Authors: Waiman Long <waiman.long@hp.com>

Original file line number	Diff line number	Diff line change
`@@ -2,6 +2,10 @@`
`2`	`2`	`/*`
`3`	`3`	`* Queue read/write lock`
`4`	`4`	`*`
	`5`	`+ * These use generic atomic and locking routines, but depend on a fair spinlock`
	`6`	`+ * implementation in order to be fair themselves. The implementation in`
	`7`	`+ * asm-generic/spinlock.h meets these requirements.`
	`8`	`+ *`
`5`	`9`	`* (C) Copyright 2013-2014 Hewlett-Packard Development Company, L.P.`
`6`	`10`	`*`
`7`	`11`	`* Authors: Waiman Long <waiman.long@hp.com>`