Update from upstream with manual merge of Yasunori Goto's

changes to swiotlb.c made in commit 281dd25cdc0d6903929b79183816d151ea626341
since this file has been moved from arch/ia64/lib/swiotlb.c to
lib/swiotlb.c

Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 20 insertions, 1 deletions

diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index 22e5f9036f3c..eb7db3c19227 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -410,7 +410,26 @@ Kernel messages do not have to be terminated with a period.
 Printing numbers in parentheses (%d) adds no value and should be avoided.
 
 
-                Chapter 13: References
+                Chapter 13: Allocating memory
+
+The kernel provides the following general purpose memory allocators:
+kmalloc(), kzalloc(), kcalloc(), and vmalloc().  Please refer to the API
+documentation for further information about them.
+
+The preferred form for passing a size of a struct is the following:
+
+        p = kmalloc(sizeof(*p), ...);
+
+The alternative form where struct name is spelled out hurts readability and
+introduces an opportunity for a bug when the pointer variable type is changed
+but the corresponding sizeof that is passed to a memory allocator is not.
+
+Casting the return value which is a void pointer is redundant. The conversion
+from void pointer to any other pointer type is guaranteed by the C programming
+language.
+
+
+                Chapter 14: References
 
 The C Programming Language, Second Edition
 by Brian W. Kernighan and Dennis M. Ritchie.