zsmalloc: add more comment
This patch adds lots of comments and it will help others
to review and enhance.
Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/drivers/staging/zsmalloc/zsmalloc.h
index fbe6bec..c2eb174 100644
--- a/drivers/staging/zsmalloc/zsmalloc.h
+++ b/drivers/staging/zsmalloc/zsmalloc.h
@@ -18,12 +18,19 @@
/*
* zsmalloc mapping modes
*
- * NOTE: These only make a difference when a mapped object spans pages
+ * NOTE: These only make a difference when a mapped object spans pages.
+ * They also have no effect when PGTABLE_MAPPING is selected.
*/
enum zs_mapmode {
ZS_MM_RW, /* normal read-write mapping */
ZS_MM_RO, /* read-only (no copy-out at unmap time) */
ZS_MM_WO /* write-only (no copy-in at map time) */
+ /*
+ * NOTE: ZS_MM_WO should only be used for initializing new
+ * (uninitialized) allocations. Partial writes to already
+ * initialized allocations should use ZS_MM_RW to preserve the
+ * existing data.
+ */
};
struct zs_pool;